ABIM - Myocardial Infarction Symptoms, Diagnosis, & Treatments

Here are key facts for American Board of Internal Medicine (ABIM) Examination from the Myocardial Infarctions: Diagnosis & Treatment tutorial, focusing on clinical management and treatment decision-making that are essential for board certification. See the tutorial notes for further details and relevant links.

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1. Global patterns: Incidence of myocardial infarctions is declining in high-income countries but rising in middle- and low-income countries. 2. Demographic variations: Within the United States, MI incidence after age 35, from highest to lowest: Black males > Black females > White males > White females. 3. Gender differences: First MI occurs approximately 10 years earlier in men than women, possibly related to risk factors such as smoking and hyperlipidemia. 4. Mortality disparities: Despite overall declining rates, mortality remains higher in women than male peers, especially for young and/or minority women. 5. Disease progression: Myocardial infarction is an important cause of heart failure, which is itself a significant cause of death. 1. Major modifiable risk factors:

• Dyslipidemia
• Diabetes mellitus
• Hypertension
• Smoking (possibly including e-cigarettes)
• Obesity
• Psychosocial stress
• Alcohol consumption
• Poor diet (low in fruits and vegetables)

2. Patient education needs: Many patients, especially women, are unaware of risk factors and symptoms. 3. Health literacy gap: Unawareness is a significant obstacle to prevention and treatment of myocardial infarction. 4. Prevention strategies: Long-term management focuses on risk factor modification through improved diet, exercise, and medications. 5. High-risk populations: Targeted screening and intervention for groups with higher incidence and mortality. 1. Definition: Myocardial infarction is defined as myocardial injury with ischemia. 2. Presentation patterns:

• Prodromal symptoms: Days, weeks, or months prior to the acute event
• Acute symptoms: Experienced at the time of the event
• Silent MI: No noticeable symptoms

3. Typical presentation: Chest pain/angina variably described as dull, sharp, squeezing, pressure, or discomfort, often radiating to arms, neck, jaw, or back. 4. Associated symptoms:

• Gastrointestinal issues (nausea, vomiting, indigestion)
• Extreme fatigue, exhaustion, or sleep disturbances
• Headaches, dizziness, lightheadedness
• Shortness of breath (dyspnea)
• Anxiety or sense of impending doom

5. Atypical presentations: Not all patients experience angina—absence of chest pain and/or young age often leads to missed or delayed diagnosis with worse outcomes. 1. ECG assessment:

• Should be administered as soon as possible when MI is suspected
• Re-administered frequently to observe the evolution of the infarction
• Distinguishes between ST-segment elevated (STEMI) or Non-ST elevated (NSTEMI) myocardial infarctions
• Q-wave abnormalities may indicate size/location of current MI, or may indicate a prior MI

2. ECG localization:

• Lateral infarction: Leads I and aVL; left circumflex artery
• Apical infarction: Leads V5 and V6; left circumflex or right coronary arteries
• Anterior infarction: Leads V3 and V4; left anterior descending artery
• Anteroseptal infarction: Leads V1 and V2; proximal left anterior descending artery
• Inferior infarction: Leads II, aVF, and III; right coronary artery or left circumflex artery (in ~10% with left dominance)
• Right ventricular infarction: Requires additional leads V3R through V6R
• Posterolateral infarction: Requires additional leads V7-V9; right coronary or left circumflex artery

3. Cardiac biomarkers:

• Cardiac troponin is key to diagnosis
• Help distinguish between NSTEMI and unstable angina (only NSTEMI shows troponin elevation)
• Both cardiac troponin I and CK-MB peak within 24 hours of MI and fall to normal levels over time

4. Coronary anatomy correlation: Understanding anatomic distribution helps localize infarcts and predict complications. 5. Integrated assessment: Combining history, physical examination, ECG, and biomarkers for comprehensive evaluation. 1. Time-dependent approach: Treatment should begin as soon as possible, ideally before hospital arrival, to reduce myocardial necrosis. 2. Pre-hospital treatment:

• Oxygen administration when oxygen saturation is less than 90%
• Aspirin for antiplatelet effects
• Nitrates for chest pain (morphine if nitrates ineffective)

3. Reperfusion strategies:

• STEMI: Emergency PCI recommended; if unavailable, immediate fibrinolytic therapy
• NSTEMI: Unstable/complicated cases require immediate PCI/CABG; uncomplicated cases may wait longer
• Fibrinolytics: Generally not recommended for NSTEMI (risks outweigh benefits)

4. Pharmacologic therapy:

• Antiplatelets: Aspirin, clopidogrel, or others
• Anticoagulation: Unfractionated or low molecular weight heparin
• Anti-ischemic: Beta-blockers or calcium-channel blockers
• Plaque stabilization: Statins, ACE-inhibitors

5. Long-term management: Risk factor modification through improved diet, exercise, and medications for hypertension and hyperlipidemia.

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1. Atypical presentation recognition: Absence of chest pain should not exclude MI from differential, especially in women, elderly, and diabetics. 2. Prodromal symptom importance: Symptoms days to months before acute MI may include fatigue, sleep disturbances, or vague discomfort. 3. Psychological manifestations: Anxiety or sense of impending doom may be harbingers of MI rather than primary psychiatric symptoms. 4. Young patient awareness: Young patients often experience missed or delayed diagnosis due to low clinical suspicion. 5. Diagnostic barriers: Unawareness is a significant obstacle to prevention and treatment—patient education is crucial. 1. Serial assessment: ECGs should be repeated frequently to observe evolution of infarction patterns. 2. STEMI vs. NSTEMI distinction: Critical for determining appropriate reperfusion strategy. 3. Lead interpretation principles: Different lead changes indicate specific coronary artery territories:

• Anterior (V3-V4): Left anterior descending artery
• Anteroseptal (V1-V2): Proximal left anterior descending artery
• Lateral (I, aVL): Left circumflex artery
• Inferior (II, III, aVF): Right coronary artery (or less frequently left circumflex)

4. Extended lead sets: Right ventricular (V3R-V6R) and posterior (V7-V9) infarctions require additional leads beyond standard 12-lead ECG. 5. Q-wave significance: May indicate size/location of current MI or evidence of prior MI. 1. Troponin primacy: Cardiac troponin is key to diagnosis of myocardial infarction. 2. NSTEMI vs. unstable angina differentiation: Only NSTEMI shows rising/falling troponin levels. 3. Temporal pattern: Both cardiac troponin I and CK-MB peak within 24 hours of MI. 4. Serial sampling value: More valuable than single determinations for diagnosis. 5. Integrated interpretation: Always interpret biomarkers in context of clinical presentation and ECG findings. 1. Reperfusion timing: "Time is myocardium"—earlier treatment leads to better outcomes. 2. STEMI management: Emergency PCI preferred; if unavailable, immediate fibrinolytic therapy. 3. NSTEMI approach: Risk stratification guides timing of intervention—unstable patients need immediate care. 4. Therapeutic pathway: Comprehensive approach with antiplatelets, anticoagulants, beta-blockers, statins, and ACE inhibitors. 5. Pre-hospital initiation: Early oxygen (when indicated), aspirin, and nitrates can limit infarct size. 1. Women: Higher mortality rates, more atypical presentations, first MI approximately 10 years later than men. 2. Racial/ethnic disparities: Black males have highest incidence after age 35, followed by Black females. 3. Mortality risk: Young and/or minority women have particularly high mortality despite overall declining rates. 4. Age considerations: Young patients often experience missed diagnosis due to low clinical suspicion. 5. Health literacy impact: Many patients, especially women, lack knowledge about risk factors and symptoms—education is essential.

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Below is information not explicitly contained within the tutorial but important for the American Board of Internal Medicine Examination. 1. TIMI Risk Score: Predicts 14-day outcomes in ACS patients. 2. GRACE Risk Score: Predicts in-hospital and 6-month mortality. 3. CRUSADE Score: Assesses bleeding risk in ACS patients. 4. DAPT Score: Guides duration of dual antiplatelet therapy after PCI. 5. PRECISE-DAPT Score: Assesses bleeding risk to inform DAPT duration. 1. P2Y12 inhibitor selection: Clopidogrel vs. ticagrelor vs. prasugrel based on clinical factors and comorbidities. 2. Anticoagulation strategies: UFH, LMWH, fondaparinux, or bivalirudin based on clinical context. 3. Beta-blocker optimization: Timing, patient selection, and contraindications. 4. High-intensity statin therapy: Specific agents and dosing for post-MI patients. 5. ACE-I/ARB selection: Timing of initiation and patient-specific considerations. 1. Cardiogenic shock: Early recognition, hemodynamic support options, and revascularization priorities. 2. Mechanical complications: Diagnosis and management of papillary muscle rupture, ventricular septal defect, free wall rupture. 3. Post-MI arrhythmias: Acute management and long-term risk stratification. 4. Right ventricular infarction: Special management considerations including volume loading. 5. Post-infarction pericarditis: Early vs. late (Dressler syndrome) presentations and management. 1. Cardiac rehabilitation: Components, benefits, and appropriate referral. 2. Target goals: LDL <70 mg/dL, BP <130/80 mmHg, HbA1c <7%, smoking cessation. 3. Medication adherence strategies: Improving compliance with life-saving therapies. 4. Return to activities: Evidence-based guidance for driving, sexual activity, exercise, and work. 5. Depression screening: Associated with worse outcomes if untreated. 1. Core quality metrics: Door-to-ECG time, door-to-needle time, door-to-balloon time. 2. Regional STEMI systems: Network organization and transfer protocols. 3. Appropriate Use Criteria: For diagnostic and interventional procedures. 4. Discharge planning: Medication reconciliation, follow-up arrangements, and transitions of care. 5. Healthcare disparities: Recognition and strategies to address gaps in MI care and outcomes.