Chapter 49: Acute Coronary Syndrome

Speaker 1 Welcome to the Tintin Alley Emergency Medicine Show, where we summarize individual chapters from Tintin Alley's Emergency Medicine Comprehensive Study Guide, 9th Edition. Today we're taking a deep dive into Chapter 49, Acute Coronary Syndromes, or ACS. This is absolutely critical for anyone working in emergency medicine, from students to seasoned attendings. Speaker 2 Yeah, definitely. Our mention today is to cut through the complexity of ACS, really distill the most vital clinically relevant information you need. We'll give you a shortcut to understanding everything from, you know, the underlying reasons why ACS happens, to diagnosing it in the chaos of the Ed, and then, importantly, managing it effectively. Speaker 1 Let's start by grasping the sheer impact of ischemic heart disease. It's, well, it's truly devastating, isn't it? It's the leading cause of death in the United States, claiming over 400,000 lives annually. And think about this, we see over 8 million Ed visits each year for chest pain and a significant chunk, about 15% of those patients will actually be diagnosed with an acute coronary syndrome. That's a That's a massive number. Speaker 2 It really is. And to be clear, ACS is like a broad term. It's an umbrella that covers everything from unstable angina or UA all the way through an acute myocardial infarction, or AMI. A key distinction here is that while every AMI is an ACS, only about maybe 1/3 of ACS patients actually have an AMI. The rest present with unstable angina, which you know, it's still a serious condition that demands our attention. Speaker 1 OK, that makes sense. So for those unstable angina presentations, what are the classic patterns we really need to recognize? Tinson Alley outlines I think 3 main types. Speaker 2 That's right, three principal presentations. First, there's rest angina. This is angina occurring when the patient's just resting and it's usually prolonged, typically over 20 minutes. Speaker 1 OK, rest angina. Got it. Speaker 2 Then you have new onset angina. This is angina that markedly limits ordinary physical activity. Things like walking just one or two blocks, or climbing a single flight of stairs. It's new for them. Speaker 1 Right. So it's a significant change in their functional capacity. Speaker 2 Yeah, exactly. And the third one is increasing angina. This is someone who already has a diagnosis of angina, but it's become distinctly more frequent or it lasts longer or it has a lower threshold. Now less activity brings it on. So it's a. Speaker 1 Worsening pattern that helps clarify things. Speaker 2 It does. And you know, to help with those critical decisions, the American College of Cardiology and American Heart Association have developed a tool, it's in Table 49 to 2 to estimate that short term risk for death or AMI in these UA patients. It helps guide management. Speaker 1 OK, that foundational understanding is crucial. Now let's maybe go a bit deeper into the underlying anatomy. And you know what specifically goes wrong? The coronary arteries. It's like the heart's own plumbing system. Speaker 2 Exactly. Think of it like that. You've got the left coronary artery, which is a major pipe. It quickly splits into the left circumflex, the LCX feeding the lateral wall mostly and then the left anterior descending. The LED often called that, yeah, because it supplies the really critical anterior and septal regions, then the right coronary artery, the RCA, handles the right ventricle and the inferior part of the left ventricle. Speaker 1 And the electrical system often has that dual supply, which is interesting. Speaker 2 It does, which offers some protection. But here's a key clinical Pearl the post remedial papillary muscle. Tiny but vital usually gets its blood from just one source, typically the RCA if that artery gets blocked. Speaker 1 Then that muscle is in serious trouble. Speaker 2 OK, right. And understanding that plumbing brings us straight to the pathophysiology at its core. Cardiac ischemia happens when the heart's oxygen demand suddenly outstrips its oxygen supply. Speaker 1 Demand versus supply. Simple concept, Complex reality. Speaker 2 Precisely supply depends on oxygen carrying capacity. Think hemoglobin, O2 saturation, and the actual blood flow through those coronaries. And that flow is influenced by diastole vascular resistance, local regulation. It's complex. Now, stable angina is usually from a fixed narrowing, but ACS that's typically a sudden event, an atherosclerotic plaque ruptures or erodes. Speaker 1 The plaque breaks open. Speaker 2 Yes, and immediately platelets, Russian aggregate, form a thrombus, A clot right there, and that clot suddenly reduces blood flow. Less commonly, you can have secondary causes like soaring oxygen demand from fever or tachycardia, or reduce flow from hypotension, or reduce delivery from severe anemia or hypoxemia. Speaker 1 You know, it's one thing to say plaque rupture, but what I find really fascinating is what happens at that microscopic level. How did the platelets actually react? It's like an emergency response system. Speaker 2 It's an incredible, very rapid process. Think of it in three steps. First, adhesion lightlets weakly interact with the exposed stuff under the vessel lining like collagen, and bind to von Willebrand factor. They just kind of stick there initially. Speaker 1 OK, initial contact. Speaker 2 Then activation. They get stimulated by things like tissue factor, thrombin, even the sheer forces of blood flow. They change shape and start releasing chemicals. Adenosine diphosphate, thrombosane A2, serotonin. These are like alarm signals. Speaker 1 Pulling in the groups and making themselves stickier. Speaker 2 Yeah, exactly. And that leads to the final step, aggregation. The activated platelets expose these receptors, glycoprotein IBA, which act like hooks. Fibrinogen or von Willebrand factor then cross links these receptors, binding the platelets tightly together. That forms the platelet plug. Speaker 1 The dam that blocks the flow. Speaker 2 Precisely. And the extent of that blockage, how much it limits oxygen delivery, that dictates the clinical presentation. Speaker 1 So stable angina is just ischemia with exertion, no clot. Speaker 2 Right, no plaque rupture, no active thrombus, right. But in ACS you have that plaque rupture, the platelet rich thrombus, and that sudden reduction in blood flow. That mismatch leads to ischemia, which can progress to necrosis, actual heart muscle death, and as the muscle dies, pump function declines. You get increased pressures in the heart, decreased cardiac output, lower blood pressure, eventually leading to heart failure, pulmonary edema, even altered mental status or kidney problems. It can spiral quickly. Speaker 1 OK, let's shift gears. We're in the Ed. Patient comes in chest pain. The history is obviously key. What are we really listening for? Characterizing the pain. Speaker 2 Absolutely, you need the details, severity, location, radiation, arm, neck, jaw or classic duration and the quality. Pressure, heaviness, tightness, fullness, squeezing are the textbook descriptions. Knife like sharp stabbing are less common for ACS. Speaker 1 And associated symptoms Nausea, vomiting. Speaker 2 Diaphoresis, sweating, dyspnea, shortness of breath, Lightheadedness, syncope, palpitations, all important clues. Any of the context, onset, duration, What precipitated it? Any prior episodes or evaluations? Speaker 1 So how do we differentiate typical angina from ACS based on history? Speaker 2 Well, typical angina is usually brief, like less than 10 minutes, often relieved pretty quickly by rest or sublingual nitroglycerin. ACS discomfort is generally more prolonged, more severe, often has more of those associated symptoms, and typically shows little response to that first dose of Nitro. Speaker 1 But then there are the non classic presentations. These are so important not to miss. Advanced age, female gender, diabetes. They're often associated with less typical symptoms. Speaker 2 Absolutely, it's a huge pitfall. Up to 37.5% of women and 27.4% of men present without chest pain. So that term atypical chest pain is honestly misleading because these presentations are quite common. Women under 55, for example, are more likely to report epigastric pain, palpitations or jaw pain instead of classic chest pressure. Speaker 1 And we shouldn't rely too heavily on traditional risk factors in the acute setting, should we? Speaker 2 That's a critical point. Things like hypertension, diabetes, smoking history, family history, hypercholesterolemia. They predict a long term coronary artery disease risk very well. But for predicting acute ACS in the Ed and someone over 40, they're actually poor predictors. Don't let their absence fool you. Speaker 1 Good reminder. OK, history done. What about the physical exam? What are the key things to look for? Speaker 2 Start with general appearance, are they comfortable or struggling to breathe? Pale, sweaty, cyanotic, then vital signs. Pulse fast, slow, regular. Irregular bradycardia can be seen with inferior MI, but it's a bad sign with anterior MI. Blood pressure extremes, high or low usually mean worse prognosis. Speaker 1 Cardiac exam murmurs extra sounds. Speaker 2 Listen for an S3 gallop. You might hear it in 1520% of AMI patients. It suggests as a failing myocardium. A new systolic murmur is really ominous. Think papillary muscle dysfunction, A flail mitral leaflet, or even a ventricular septal defect. These are surgical emergencies. Speaker 1 And signs of heart failure. Speaker 2 Right. Look for rails in the lungs, maybe with that S3 that points to left ventricular dysfunction, left sided heart failure, and then jugular venous distention, hepatojugular reflex, peripheral edema. Those suggest right sided heart failure. OK, so nailing down the diagnosis, it really hinges on different criteria for STEMI&STEMI and unstable angina. Speaker 1 Right, STEMI is mainly ECG changes plus symptoms. NSTEMI needs those elevated cardiac biomarkers, maybe with some ECG changes that don't meet STEMI criteria. Speaker 2 Exactly. And unstable angina is purely clinical based on that history we talked about those three patterns, the ECG and biomarkers are non diagnostic for UA itself. Speaker 1 And the ECG, it's the single best test, right? Got to get it fast. Speaker 2 Absolutely within 10 minutes of presentation for anyone with suggestive symptoms. Ideally interpreted quickly too. Pre hospital ECG's huge benefit saves time. Speaker 1 So looking at the ECG for localization, St. elevation in 2-3 AVF means inferior. Speaker 2 Correct. V1 to V4 is anterior or anteroceptile. V5V6 IAVL point to lateral involvement. Speaker 1 And for any inferior MI you absolutely have to get that right sided V4 lead. Speaker 2 Crucial St. elevation in V4R strongly suggest RV infarction which changes management. And don't forget posterior leads V7 to V9 if you suspect A posterior MI may be seeing reciprocal depression in V1V3. Speaker 1 What about reciprocal changes? Why are they important? Speaker 2 Reciprocal St. depression in leads opposite the St. elevation usually indicates a larger area of injury, increased severity, worse pump function, and higher risk of complications and mortality. It's a sign of a bigger problem, and sometimes specific ECG patterns can point right to the culprit artery. Like St. elevation in lead 3 being greater than in lead 2 strongly suggests an RCA occlusion. Speaker 1 OK. And what about lead VR elevation there is concerning. Speaker 2 Very concerning. St. elevation in AVR, especially if it's higher than the elevation in V1, can indicate a left main coronary artery occlusion or severe 3 vessel disease. That's a critical finding needing urgent attention. Speaker 1 Interpretation gets tricky though, especially with things like a pre-existing left bundle branch block. How do we diagnose an MI then? Speaker 2 That's where Scarbosa's criteria come in. It can be a lifesaver. The most specific finding, the one with the highest odds ratio, is concordant St. elevation of 1mm or more. That means the St. segment goes in the same direction as the main QRS deflection. Speaker 1 In cordant, elevation equals highly likely MI. Speaker 2 Exactly. Also look for concordant St. depression of 1mm or more in leads V1V2 or three, and finally excessively discordant St. elevation of 5mm or more where the St. goes opposite the QRS. But by a large amount. Any of those positive criteria significantly increase the likelihood of AMI in the setting of an LBB. Speaker 1 OK, Scarbosa for LBB. What about Wellens's sign? That's another critical pattern, right? Speaker 2 Absolutely critical. Wellens's sign involves specific T wave abnormalities, either deeply inverted or biphasic T waves, typically in leads V2 and V3, but often extending to V1 or V4V6. The key is this pattern is often seen when the patient is pain free, but it signifies critical stenosis of the proximal LAD artery. These patients are at extremely high risk for a massive anterior MI soon and need urgent intervention. Speaker 1 Don't miss Wellens. OK, moving to serum markers for STEMI, the ECG is enough, right? We don't wait for markers. Speaker 2 Correct STEMI diagnosis is based on ECG. Reperfusion shouldn't be delayed waiting for biomarkers. Markers are essential for diagnosing NSTEMI and for risk stratification in all ACS patients. Speaker 1 And troponin is the go to marker. Speaker 2 Yes, cardiac troponin either IRT is the preferred biomarker. It's highly sensitive and specific for myocardial necrosis. But, and this is important, elevated troponin indicates cardiac injury, not necessarily ACS. Lots of other things can cause troponin elevation. Speaker 1 Like PE, sexes, kidney disease. Speaker 2 Exactly. That's where the high sensitivity cardiac troponins HSCTN come in. They detect injury earlier and more reliably. But the key with high sensitivity troponin is the delta, the change in value over one to three hours that helps distinguish acute injury like an ACS from chronic elevation. Speaker 1 So serial testing is still the standard, yes? Speaker 2 Serial troponin testing is still recommended, either A2 hour delta for high sensitivity assays or using validated zero and one hour rapid algorithms. A single undetectable high sensitivity troponin plus no ischemic ECG changes makes ACS very unlikely. Speaker 1 And the level matters, right? Higher troponin equals worse prognosis. Speaker 2 Absolutely. Any measurable elevated troponin implies myocardial injury and a worse prognosis, and the degree of elevation matters. More elevation generally correlates with more damage and higher risk. Speaker 1 What about BNPB? Speaker 2 Type natriuretic peptide is often elevated in ACS and does indicate higher risk, but it's not routinely measured for ACS diagnosis because it's less specific for acute coronary events compared to troponin. It's more a marker of ventricular stress and heart failure. Speaker 1 OK, diagnosis covered. Let's shift to treatment once we suspect or confirm ACS. What are the immediate Ed Seps guided by symptoms, history, exam, ECG. Speaker 2 Right, First things first. Establish IV access. Give aspirin 162 to 325 milligrams. Chewable is preferred if EMS hasn't already. Assuming no major contraindications, get the patient on continuous ECG monitoring. Speaker 1 What about oxygen? Standard practice, but is it always needed? Speaker 2 That's a good point. Traditionally everyone got oxygen, but the evidence for benefit in patients without hypoxemia, meaning O2 saturation above 9092%, is actually lacking. Some small studies even suggested potential harm with high flow oxygen. So the current thinking is to use supplemental O2 only if the patient is hypoxemia, semic, in respiratory distress, or has clear signs of heart failure. Speaker 1 Okay, judicious oxygen use. The main goals are reperfusion and limiting in fart size. Speaker 2 Exactly, those are the pillars. Achieve immediate reperfusion, especially in STM I, and minimize the amount of heart muscle that dies. Speaker 1 So let's dive into STM I treatment. First time is muscle reperfusion options. Speaker 2 2 main options for STEMI reperfusion mechanical which is percutaneous coronary intervention or PCI. Basically angioplasty and maybe scenting or pharmacologic using fibrinolytic therapy, clot busting drugs. Speaker 1 And the time goals are critical here. Speaker 2 Absolutely critical. If the patient presents to a hospital capable of doing PCI, the goal is first medical contact to device time getting that balloon inflated or stent deployed in less than or equal to 90 minutes. Speaker 1 OK, 90 minutes at a PCI center. What if they're at a hospital? They can't do PCI. Speaker 2 Then the goal is to transfer them to a PCI capable center quickly enough so that the total time from first medical contact to device deployment is less than or equal to 120 minutes. Speaker 1 120 minutes if transfer is needed and if you can't meet those PCI time goals. Speaker 2 Then fiber analysis is the alternative if PCI isn't possible within those timeframes. The goal is to administer fiber analytics within 30 minutes of the patient arriving at the hospital. The door to needle time. Speaker 1 Got it. And of the EDSTMI patients are getting other meds too, right? Antiplatelets. Antithromics. Speaker 2 Yes. Besides aspirin, they'll typically get another antiplatelet agent like AP2Y12 inhibitor and an anticoagulant like heparin or anoxaparin. Nitrates are often used for symptom control too. We'll get into the specifics of those drugs shortly, OK? Speaker 1 How does treatment differ for NSTEMI? It seems less immediately time critical than STEMI, but still serious. Speaker 2 You're right, the urgency is slightly different, but POMP treatment is still key. For most NSTEMI patients, an invasive approach with cardiac catheterization and likely PCI within 24 to 48 hours is recommended. The strategy has been shown to reduce the combined risk of death, MI or recurrent ACS. So. Speaker 1 CAF lab within a day or two for most NSTEMI, but some need to go sooner. Speaker 2 Yes, an earlier invasive approach meaning Cath lab within two hours is indicated for high risk NSTEMI patients. These are patients with things like refractory angina despite medical therapy, hemodynamic instability like hypotension or shock, electrical instability like life threatening arrhythmias, signs of worsening heart failure, recurrent ischemic changes on ECG or significantly elevated troponins. These patients are unstable and need intervention sooner. Speaker 1 Makes sense now. PCI is generally preferred over fibrinolytics for STEMI when it can be done in a timely manner. Why is that? Speaker 2 PCI is preferred primarily because it's more effective at restoring normal coronary blood flow, what we call TMI. Three flow angioplasty physically opens the artery with a balloon, disrupting the plaque and stents provides scaffolding to keep it open. Compared to fibrinolysis, primary PCI leads to lower rates of death, reinfarction, stroke, especially hemorrhagic stroke and other major cardiovascular complications. Its benefit actually increases the longer the symptoms have been present. Speaker 1 And those drug eluting stents, they reduce early closure but have that risk of late thrombosis if antiplatelets are stopped. Speaker 2 Exactly. Drug eluting stents release medication to prevent scar tissue buildup, reducing the risk of restonosis compared to bare metal stents. But they require longer duration of dual antiplatelet therapy because there's a small but real risk of late stent thrombosis if drugs like lepetabrile or tacogrelar are stopped too early, sometimes months or even a year later. Speaker 1 So optimizing door to balloon time is huge for PCI centers. Speaker 2 Absolutely. Strategies like having EMS transmit the ECG to activate the Cath lab from the field, having a dedicated team ready to respond, 247 single call activation systems, and continuous quality feedback loops are all crucial for minimizing delays and improving outcomes. Speaker 1 OK, but if PCI isn't an option within the time window, fibrinolytics are the way to go for STEMI. What are the key agents? Speaker 2 The common fibrinolytic agents include tissue plasminogen activator TPA, aldoplas, recombinant tissue plasminogen activator RPA, retoplas, tenectoplas, TNK TPA, and older agents like streptokinase and anastroplas. Tenectoplas is often preferred now due to its ease of administration as a single bolus. Speaker 1 And they work by activating plasminogen. Speaker 2 Correct, they are plasminogen activators. They convert plasminogen, which is naturally present in the blood, into plasmin. Plasmin is an enzyme that directly breaks down fibrin. The protein mesh work that holds the clot together so they dissolve the thrombus. Speaker 1 What are the main benefits? Speaker 2 Improved left ventricular function and most importantly, reduced mortality. Studies show a net motifet of saving over 30 lives per 1000 patients treated within the first few hours of symptom onset. Speaker 1 Indications are STEMI with onset less than 612 hours and specific ECG criteria. Speaker 2 Yes, symptom onset, ideally less than 12 hours. Some benefit and may extend beyond that in certain cases, but the earlier the better. And ECG criteria are usually at least 1mm of St. segment elevation in two or more contiguous leads. Speaker 1 But they come with significant risks, mainly bleeding. What are the major contraindications? Speaker 2 Bleeding is the main concern. Absolute contraindications are designed to identify patients at highest risk for catastrophic bleeding, especially intracranial hemorrhage. These include any prior intracranial hemorrhage, known structural cerebral vascular lesion like an AVM, malignant intracranial neoplasm, ischemic stroke within the last three months unless it's an acute stroke within 4.5 hours being treated with melytics. Suspected aortic disception, active bleeding or bleeding diathesis excluding menses, and significant closed head or facial trauma within three months. Speaker 1 That's a critical list to know. Intracranial bleeding is the most feared complication. Speaker 2 By far it's the most catastrophic complication of fibrinolytic therapy. There are also relative contraindications like severe uncontrolled hypertension, systolic 180 or diastolic 110, recent major surgery or trauma, recent internal bleeding, non compressible vascular punctures, pregnancy, active peptic ulcer disease, or current use of anticoagulants. You have to weigh the risks and benefits carefully. Speaker 1 What about pharmacoinvasive therapy? Lytix then transfer for PCI. Speaker 2 Yes, that's a strategy particularly useful for high risk STEMI patients presenting to non PCI capable hospitals where transfer times might be prolonged. Giving fibrinolytics immediately and then transferring the patient for angiography and potential PCI within 3 to 24 hours has shown benefits over Olytics alone, especially in reducing reinfarction. Speaker 1 Despite your benefits, Olytics aren't perfect right limitation. Speaker 2 Right. They don't achieve complete reperfusion TMI three flow in about 4050% of patients. They can also paradoxically increase thrombin generation, potentially promoting reocclusion. And there's always that risk of intracranial hemorrhage, about .51%. Speaker 1 And after lytics, patients need anticoagulation. Speaker 2 Yes, absolutely. Full dose anticoagulation is needed for a minimum of 48 hours or until revascularization if that happens sooner. Options include unfractionated heparin, anoxaparin, or fondaparinux depending on the specific fibranolytic used and local protocols. OK, let's dive into the specific medications in more detail. These are the drugs you'll be ordering and administering in the Ed. Let's start with antiplatelet agents. Aspirin is first line. Dose is 162 to 325 milligrams, given as soon as possible, preferably chewed for faster absorption. It works by irreversibly inhibiting cycloxygenase, preventing from boxing A2 formation. Its impact is huge. It reduces the mortality rate by about 23% in STEMI. Speaker 1 So basically everyone with suspected ACS gets aspirin unless they have a true allergy or major active bleeding concern. Speaker 2 Pretty much, the benefits far outweigh the risks in most cases. Don't withhold it for minor GI upset history or theoretical concerns without a strong contraindication. Next up are the adenosine diphosphate receptor antagonists, the P2Y12 inhibitors. These work differently than aspirin blocking platelet activation via the P2Y12 receptor. We have several options. Pressure grill effenant is an irreversible potent inhibitor. The loading dose is typically 60 milligrams orally, followed by a maintenance dose, usually 10 milligrams daily, but sometimes 5 milligrams in lower weight or older patients. Key things about prostagrill. It generally provides stronger platelet inhibition than clopidogrel and reduces ischemic events more, but it comes with a higher risk of bleeding. It's contraindicated in patients with a history of stroke or Tia due to increased intracranial hemorrhage risk. Caution is also advised in patients over 75 years old or those weighing less than 60 kilograms. It's typically initiated only after coronary anatomy is known, usually in the Cath lab. Speaker 1 OK so pressure grill is potent but riskier bleeding wise and usually started post Cath. What about Tikagreler? Speaker 2 Tikagreler Brilinta is a reversible P2Y12 inhibitor. The loading dose is 180 milligrams orally followed by 90 milligrams twice a day. Studies like Plato showed it decreased the composite outcome of cardiovascular death, MI or stroke compared to clopidogrel without a significant difference in overall major bleeding, although non CABG related bleeding was higher. It can be started in the Ed for ACS patients whether managed medically or invasively. A common side effect is dyspnea, which is usually transient. Speaker 1 And copidogrel, the older option. Speaker 2 Copidogrel Plavix is still widely used. Loading dose is usually 300 to 600 milligrams orally followed by 75 milligrams daily. The 600 milligram load provides faster and stronger platelet inhibition. It improves outcomes when added to aspirin and anti promin therapy, especially in the setting of fibrinolysis. Important caveats for clopidogrel. It's a pro drug meeting conversion by liver enzymes, particularly CYP 2C-19. There's genetic variability in this enzyme, so some patients are poor metabolizers and may not get the full benefit. The FDA also has warnings about reduced efficacy when used concurrently with proton pump inhibitors like omeprazole, which inhibits CYP 2C-19. If elective CABG is planned, kloppenbogrel should ideally be held for five days beforehand to reduce bleeding risk. Speaker 1 That CYP 2C-19 interaction is key. What about the glycoprotein IBEA inhibitors? Epsixomab. Eptifibatite, Tyrofiban? Are these common Ed drugs anymore? Speaker 2 Less so for routine Ed initiation. These are very potent intravenous antiplatelet agents that block the final pathway of platelet aggregation. Dosing varies. Epsiximab is a .25 milligrams per kilogram bolus than infusion. Eptifibatide is a double bolus of 180 micrograms per kilogram than infusion. Tirofibin has a weight based bolus and infusion regimen. The main take away for the Ed is that routine upfront use isn't generally recommended anymore based on current evidence, especially with the availability of potent oral agents like pursue grill and takagriller. They significantly increase bleeding risk. They're typically reserved for specific high risk situations, often during PCI, like managing a large thrombus burden or procedural complications usually initiated by the interventional cardiologist. Speaker 1 OK, so mostly Cath lab drugs. Now let's move to antithrombens, the anticoagulants, unfractionated heparin. Speaker 2 Unfractionated heparin UFH is a classic for ACS. The typical bolus is 60 units per kilogram, maximum 4000 units, followed by an infusion starting at 12 units per kilogram per hour, maximum 1000 units per hour. The infusion must be titrated based on activated partial thromboplaston time APT TT measurements, usually aiming for a target range of 1.5 to 2.5 times the control value or based on anti axle levels per institutional protocol. Downsides of UFH include its unpredictable anticoagulant response requiring frequent monitoring and the risk of heparin induced thrombocytopenia HIT. Speaker 1 What about low molecular weight heparins like anoxaparin? Speaker 2 Anoxaparin Lovenox is often preferred due to its more predictable pharmacokinetics and ease of administration. For STEMI patients, especially those under 75 receiving fibrinolytics or initial medical management, the dose is typically a 30 milligram IV bolus followed by 1 milligram per kilogram subcutaneously every 12 hours, with dose adjustments for age 75 and renal impairment. For unstable angina or NSTEMI, the dose is 1 milligram per kilogram subcutaneously every 12 hours, or daily if creatinine clearance is 30 MO. Men No IV bolus is typically given for NSTEMIUA. Anoxaparin generally provides more reliable anticoagulation than UFH. Speaker 1 Flonoparinex That's factors and specific. Speaker 2 Flonoparinex Arixtra selectively inhibits factor, say the dose for ACS is 2.5 milligrams subcutaneously once daily. It has shown similar efficacy to anoxaparin in NSTEMI with potentially less major bleeding. However, a key point from the Oasis 6 trial in STMI, Fondaparonex alone was associated with an increased risk of catheter thrombosis during PCI. So if a patient on Fondaparinex goes for PCI, they need additional anticoagulation with UFH during the procedure. It's not recommended as sole anticoagulant for primary PCI. Speaker 1 Important procedural point, Yeah. And vivolarudin, the direct thrombin inhibitor. Speaker 2 Vivarudin angiomax is a direct thrombin inhibitor given intravenously. The dose is typically a .75 milligrams per kilogram bolus followed by an infusion of 1.75 milligrams per kilogram per hour for the duration of PCI. It's mainly used in the Cath lab setting, particularly for patients undergoing PCI studies like Horizons. Amythrodit resulted in less major bleeding compared to UFH plus a glycoprotein IBA inhibitor in STEMI patients undergoing primary PCI, although there might be a slightly higher risk of acute stent thrombosis. Speaker 1 OK, that covers the antiplatelets and antithrombons. What about other therapies aimed at reducing ischemia or infarct size? Nitroglycerin. Speaker 2 Nitroglycerin is a mainstay for symptom relief. Sublingual .4kg every 5 minutes for up to three doses as needed for ongoing chest pain, provided the patient isn't hypertensive. Intravenous nitroglycerin is used for persistent ischemia, heart failure or hypertension. Start the infusion low, maybe 10 micrograms per minute, and titrate up every few minutes. Critically, you titrate to effect, usually aiming for 10% reduction in mean arterial pressure. MAP if norm intensive or up to a 30% reduction MAP if hypertensive. Don't just titrate to pain relief, monitor blood pressure closely. Speaker 1 And cautions with Nitro inferior MI RV involvement. Speaker 2 Absolutely. Nitrates reduce preload in patients with inferior MI, especially if there's RV involvement. Preload reduction can cause profound hypotension. Use extreme caution or avoid nitrates altogether in these patients. Also, a critical contraindication do not give nitrates to patients who have used phosphodiesterase inhibitors for erectile dysfunction recently. Within 24 hours for siltinophil or vardenophil and within 48 hours for tadalafil due to the risk of severe refractory hypotension. Speaker 1 Got it. Beta blockers, Metaprolol. Atenolol. Speaker 2 Beta blockers are generally beneficial after ACS by reducing myocardial oxygen demand, heart rate and possibly arrhythmias. Oral beta blockers like Metoprol 2550 milligrams orally every six 12 hours or Atenolol 2550 milligrams orally daily should ideally be started within the 1st 24 hours in patients who are hemodynamically stable and don't have contraindications. The routine use of intravenous beta blockers early on is generally discouraged now as studies like Kumate showed an increased risk of cardiogenic shock, especially in high risk patients. So start oral, not IV, unless there's a specific indication like controlling tachyrhythmias or severe hypertension. Speaker 1 And when should we definitely withhold beta blockers initially? Speaker 2 Withhold them if there are any signs of heart failure like pulmonary edema, evidence of a low output state, increased risk factors for cardiogenic shock, Age 70, systolic BP120 heart rate 110 or 60, or other standard contraindications like a long PR interval .24 seconds, second or third degree heart block without a pacemaker or active asthma, active airway disease. Speaker 1 OK, ACE inhibitors. Speaker 2 Angiotensin converting enzyme inhibitors like lisinopril, captopril, and alprol or angiotensin receptor blockers, Arbs if intolerant to acai, are important for long term mortality benefit after AMI. Oral therapy should be started within 24 hours for patients with STEMI, especially anterior MI or those with clinical heart failure or a left ventricular ejection fraction less than or equal to 40% unless contraindicated. Contraindications include significant hypotension, systolic PP100, known bilateral renal artery stenosis, or a history of angioedema with ACE. IRB use magnesium. Magnesium replacement is important if the patient is documented to be hypomagglecemic. It's also indicated for treating torsades de points or managing arrhythmias associated with a prolonged QT interval. Routine administration of magnesium to all AMI patients solely to reduce infarct size is not currently recommended based on conflicting data, although some argue it might be beneficial in high risk subgroups. Focus on correcting low levels. Speaker 1 And calcium channel blockers. Verapamil diltyasm. Speaker 2 Calcium channel antagonists, non dihydropyridines like verapamil and diltyasm generally do not reduce mortality after AMI and may even be harmful, particularly in patients with left ventricular dysfunction or heart failure. Due to their negative endotropic effects, their role is very limited. They might be considered for ongoing or recurrent ischemia or for rate control and atrial fibrillation with a rapid ventricular response only if the patient has preserved LV function. No signs of heart failure, no significant AV block and beta blockers are contraindicated or ineffective. A very specific narrow indication. Speaker 1 OK, that's a fantastic rundown of the meds. Now, despite all these treatments, complications can still happen. What are the big categories we need to watch out for? Speaker 2 Dysrhythmias and conduction disturbances are incredible, notably common seen in maybe 72 to 100% of AMI patients. On monitoring, they run the gamut. Speaker 1 Like what? Tachycardias. Bradycardias. Speaker 2 Both. Sinus tachycardia is common, often reflecting pain, anxiety or heart failure. If it persists, it's a poor prognostic sign and you need to find and treat the underlying cause. Atrial fibrillation occurs frequently, especially in the 1st 24 hours. Often transient if it causes hemodynamic compromise. Immediate cardioversion is needed if stable rate control with beta blockers or calcium channel blockers if no LV dysfunction or maybe amiderone anticoagulation is usually indicated for Afib. What? Speaker 1 About slow rhythms, bradycardias, heart blocks. Speaker 2 Sinus bradycardia, especially with inferior MI, is common and often benign if asymptomatic. Atropine is the first line drug for symptomatic bradycardia or AV block. Higher degree AV blocks second degree mobits second. Third degree can occur, particularly with anterior MI, poor prognosis, or inferior MI. Temporary pacing might be required. Pacing doesn't reduce mortality itself, but it prevents hemodynamic collapse from severe bradycardia or assistly. Speaker 1 Indications for pacing. Speaker 2 Generally, symptomatic bradycardia is unresponsive to Atropine Mobitz tend second degree AV block, third degree AV block, or alternating bundle branch block. Table 4912 in Tintanali lists the specific indications for temporary pacing. Both transcutaneous and transvenous pacing can be used. Speaker 1 Ventricular arrhythmias. Vtach V Fib. Speaker 2 Ventricular premature contractions. PVC's are common and usually benign. Accelerated IDIO ventricular rhythm AIVR often occurs during reperfusion and typically doesn't require treatment. Early ventricular tachycardia Vtach can occur but is often transient. Delayed or sustained. VTAT is more serious. Ventricular fibrillation V Fib is the most common cause of sudden death early after MI Primary V fib occurring early without heart failure is often responsive to Defibrillation. Secondary V Fib occurring later, usually with pump failure, has a much higher mortality rate. Speaker 1 Bundle branch blocks. Speaker 2 New onset right bundle branch block or especially new left bundle branch block during AMI are associated with increased myocardial damage and higher mortality. However, it's important to note that a new or presumed new LBB alone is no longer considered an automatic STEMI equivalent, requiring immediate reperfusion in the most recent guidelines due to the higher rate of false positives. You need other concerning features or scarbalsa criteria. Speaker 1 OK, heart failure is another major complication, right? Affecting 1520%. Speaker 2 Yes, and it's a spectrum. It starts with diastolic dysfunction, impaired relaxation, then progresses to systolic dysfunction, weakened contraction as more muscle dies, leading to decreased cardiac output. The severity matters hugely for prognosis. Mortality climbs steeply from around 10% with no heart failure signs all the way up to 5080% in patients who develop cardiogenic shock. An elevated BNP level also signals a worse outcome. Speaker 1 That vicious cycle of shock. Low output, low pressure, less coronary perfusion, more ischemia. Speaker 2 Exactly. Breaking that cycle requires careful fluid management, avoiding overload but ensuring adequate preload, especially in RV failure. Potential use of inotropic agents like dobutamine or milrinone, or vasopressors like norepinephrine if hypotensive and critically, early reperfusion PCI is strongly recommended for STEMI patients under 75 years old who developed cardiogenic shock. Then there are the mechanical complications. These are truly terrifying and usually involve tearing or rupture of the dead heart muscle. You don't see these with unstable angina, only with actual infarction. Speaker 1 Like the wall rupturing? Speaker 2 Exactly. Ventricular free wall rupture usually happens one to five days post MI. It leads to bleeding into the pericardial SAC, causing pericardial tamponade and usually rapid deterioration and death unless recognized and treated surgically immediately. Presents often with setting severe chest pain, hypotension, EMD. Speaker 1 What about rupture of the septum between the ventricles? Speaker 2 Interventricular septum rupture also occurs days after MI patients present with chest pain, sudden onset dyspnea, signs of right and left heart failure, and typically a new loud holosystolic murmur, often accompanied by a palpable thrill along the left sternal border. Doppler echocardiography confirms the diagnosis, showing blood flowing across the defect. Treatment is surgical repair. Speaker 1 And papillary muscle rupture leading to valve problems. Speaker 2 Right papillary muscle rupture happens in about 1% of AMI patients, more commonly with inferior MI Typically, three to five days post infarction, the papillary muscles anchor the mitral valve leaflets. If one ruptures, you get sudden, severe mitral regurgitation. Patients present with acute dyspnea, pulmonary edema, heart failure, and often a new Hollis systolic murmur loudest at the apex. Again, diagnosis is via ECHO and treatment is emergent surgical valve repair or replacement. Speaker 1 These sound like Ed nightmares. What about pericarditis after an MI? Speaker 2 Early post AMI pericarditis is less common now with reperfusion therapy may be occurring in less than 5% of patients. Usually two to four days after the MI. It presents with pleuritic chest pain, worse with deep breaths relieved by sitting forward. You might hear a pericardial friction rub. Treatment is primarily symptomatic with high dose aspirin, like 650 milligrams orally every four to six hours or colchicine .6 milligrams twice daily. We try to avoid other NSAIS like ibuprofen because they can interfere with aspirin's antiplatelet effect and potentially impair scar healing, possibly leading to scar thinning or even rupture. Speaker 1 Dresler Syndrome. That's later, right? Speaker 2 Yes. Dresler syndrome is a late post AMI autoimmune phenomenon occurring weeks to months, typically 210 weeks after the infarction. It presents with fever, malaise, chest pain, pleura, pericarditis, and sometimes pericardial or plural effusions. Treatment is similar aspirin and colchicine. Speaker 1 OK, let's talk specifically about right ventricular infarction. It usually happens with inferior M is. Speaker 2 Correct RV infarction rarely occurs in isolation. It's usually a complication of an acute inferior wall MI, seen in about 30% of those cases. The RCA typically supplies both the inferior wall and the right ventricle. Diagnosis is suspected clinically with a triad of hypotension, clear lung fields, and elevated jugular venous pressure, especially in the setting of an inferior MI. The key diagnostic ECG finding is St. segment elevation in the right sided procordial leads, particularly V4R. Speaker 1 And treatment is different. What's the key thing not to do? Speaker 2 The key thing is enonitrates. RV function is highly dependent on preload. Nitrates reduce preload and can cause profound refractory hypotension in RV infarction treatment focuses on maintaining preload with intravenous fluid resuscitation, often 1 to 2 liters of normal saline initially guided by hemodynamics. You also want to reduce RV after load if possible, though options are limited and provide in a Tropic support like dobutamine if needed for low cardiac output despite fluids, early reperfusion of the culprit RCA is also crucial. Speaker 1 And pacing might be needed too. Speaker 2 Yes, high degree AV block is common with RV infarction due to ischemia of the AV node, also often supplied by the RCA. Restoring atroventricular synchrony with AV sequential pacing can significantly improve cardiac output in these patients if they develop heart block and are hemodynamically compromised. OK. Speaker 1 Any other complications we should briefly mention? Speaker 2 Things like left ventricular thrombus formation, risk of embolization, or ventricular aneurysm can occur later, usually not presenting acutely to the Ed as the primary issue. Recurrent or refractory ischemia despite maximal medical therapy is an indication for urgent coronary catheterization. For hemodynamically unstable patients needing a bridge to Cath or surgery, especially if transport is needed, an intra aortic balloon pump might be used for temporary support. OK. Speaker 1 That covers the major complications. Let's finish up by touching on some special populations or situations. What about chest pain after a procedure like PCI? Speaker 2 Critical point If a patient presents with ACS symptoms shortly after having PCI, angioplasty or stenting, you must consider abrupt vessel closure or acute stent thrombosis as the cause until proven otherwise. This is an emergency. Treat them aggressively as ACS and get an emergent cardiology consult for likely immediate re catheterization. Remember that late stent thrombosis can occur even months later with drug eluting stents if dual antiplatelet therapy is stopped prematurely. Speaker 1 Cocaine or amphetamine use, How does that change things? Speaker 2 Cocaine associated myocardial infarction often occurs in younger patients. Although the average age is rising, troponin is still the most sensitive biomarker. Treatment mainstays are aspirin, nitrates, and importantly benzodiazepines like lorazepam or diazepam which help reduce sympathetic Dr. heart rate and blood pressure. The key difference? Beta blockers are generally contraindicated in the acute setting. Verse 24 hours of cocaine induced ACS due to concerns about unopposed alpha adrenergic stimulation potentially worsening coronary vasoconstriction. PCI is the preferred reperfusion strategy for cocaine induced STEMI. For amphetamine induced ACSECG findings can be less reliable and medical management with nitrates and benzodiazepines is often the primary approach. Again, avoiding beta blockers initially. What about? Speaker 1 ACS occurring alongside other major medical problems like GI bleed or stroke. Speaker 2 ACS is known to occur more frequently during or shortly after other acute medical stressors like major GI bleeding, stroke, severe infection, sepsis, or even extreme emotional upset. Managing these patients is complex because the treatments for ACS, especially antiplatelets and anticoagulants, can worsen the other condition. Management needs to be highly individualized, carefully weighing the risks and benefits of standard ACS therapies. If reperfusion is indicated for STEMI in this context, PCI is generally strongly preferred over fibrinolysis due to the lower risk of systemic bleeding. Speaker 1 And finally, the challenge of nights and weekends. Speaker 2 Yeah. Unfortunately, studies have shown that patients presenting with ACS during off hours, nights, and weekends sometimes experience delays in diagnosis and treatment, particularly time to PCI, compared to those presenting during regular weekday hours. These delays can adversely impact outcomes. It highlights the need for robust hospital systems and protocols to ensure timely, consistent care 24/7. Speaker 1 So what does this all mean? After this incredibly detailed discussion, let's try to boil it down. Can you recap the high yield? Key takeaways from our deep dive into acute coronary syndromes in about 60 seconds. Speaker 2 OK 62nd summary ACS common critical remember atypical presentations, especially in women, the elderly, diabetics. Your 12 lead ECG is vital. Get it within 10 minutes, repeat if needed and know the patterns. Inferior MI needs V4R for RV check, look for a VR elevation. Recognize well and sign for critical LED stenosis. Troponins diagnose NSTEMI use cereals, especially high sensitivity with deltas to confirm acute injury. Reperfusion is paramount for STEMIPCI is preferred if timely A-90 min direct A120 min transfer fiber analytics if PCI delayed door to needle 80 minutes. Master the core meds aspirin, ASCP, P2I-12 inhibitors, clopidogrel, Chicago or prostagrel. Know their nuances. Antithrombens U FH and oxiperin. Maybe fondaparonex or bevilirudin. Know the context Nitroglycerin titrate to blood pressure such as pain, Avoid an RV infarct a recent PDE 5 use oral beta blockers within 24 hours of stable Avoid IV routinely and if shock heart failure signs watch for mechanical complications rupture need surgery special populations post PCI pain closure cocaine and O&O beta blockers initially individualized care always. Speaker 1 That was a truly comprehensive deep dive into acute coronary syndromes. We hope this exploration helps you feel even more well informed and confident as you tackle these challenging cases in the Ed Go forth and apply that knowledge.