Act as a World-Class Professor of General Medicine, Clinical Pharmacology, Pathology, and Medical Education. Teach me ischemic heart disease in a simple, exam-oriented, and clinically practical manner. For every disease, follow this format: 1. Definition - One-line exam definition - Simple explanation 2. Causes (Etiology) - Common causes - Important risk factors 3. Types / Classification - Brief explanation of each type 4. Pathophysiology - Step-by-step flowchart with arrows - Easy to understand 5. Clinical Features - Symptoms - Signs - Explain why important symptoms occur 6. Key Symptoms That Suggest the Diagnosis - Hallmark symptom - Classic clinical clues - Red flag findings 7. Laboratory Investigations Create a table: Investigation | Expected Finding | Clinical Significance Include: - CBC - Biochemistry - Disease-specific tests - Imaging findings if relevant 8. Differential Diagnosis Create a comparison table: Disease | Similar Features | Differentiating Features 9. Short Clinical Case Example format: "A 55-year-old male presents with chest pain radiating to the left arm, sweating, and breathlessness. ECG shows ST elevation in leads II, III, and aVF. Troponin-I is elevated." Diagnosis: Reasoning: Provide only 1–2 short high-yield cases. 10. Treatment A. Non-Pharmacological Treatment B. Pharmacological Treatment Create a table: Drug | Drug Group | Mechanism of Action | Indication | Dose | Major Adverse Effects For every disease mention: - Drug of Choice (DOC) - First-line drugs - Alternative drugs - Emergency drugs (if applicable) 11. Clinical Pearls - Important bedside clues - High-yield exam facts - Viva points 12. Common Diagnostic Mistakes - Frequently missed findings - Common confusion with other diseases - How to avoid errors 13. 5-Minute Revision Summary Definition → Causes → Pathophysiology → Symptoms → Investigations → Treatment → Complications Teaching Rules: - Use simple English. - Explain like teaching a final-year medical student. - Use tables and flowcharts. - Focus on practical diagnosis and treatment. - Focus on exam-oriented points. - Mention standard drug doses whenever possible. - Keep the explanation concise but complete.
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🫀 Ischemic Heart Disease (IHD) - Complete Exam-Oriented Teaching Guide
Sources: Robbins & Kumar Basic Pathology (9th ed), Harrison's Principles of Internal Medicine 22E, Braunwald's Heart Disease, Goldman-Cecil Medicine, Katzung's Clinical Pharmacology, Washington Manual of Medical Therapeutics
1. DEFINITION
One-line exam definition:
Ischemic Heart Disease (IHD) is a group of syndromes caused by an imbalance between myocardial oxygen supply and demand, most commonly due to obstructive coronary artery atherosclerosis.
Simple explanation:
The heart muscle needs a continuous supply of oxygenated blood through the coronary arteries. When this supply is reduced (usually because of a blocked or narrowed artery), the heart muscle becomes starved of oxygen - this is called ischemia. Depending on how severe and how long this ischemia lasts, the patient gets angina (pain but no cell death), a heart attack (cell death), or can even die suddenly.
IHD is the leading cause of death worldwide, accounting for ~7.5 million deaths per year. - Robbins & Kumar Basic Pathology
2. CAUSES (ETIOLOGY)
Primary Cause (>90% of cases):
- Coronary artery atherosclerosis - gradual plaque build-up narrowing the coronary lumen
Other Causes (Oxygen Supply-Demand Mismatch):
| Mechanism | Examples |
|---|---|
| Increased demand | Tachycardia, hypertension, hyperthyroidism, fever |
| Reduced blood volume | Hypotension, hemorrhagic shock |
| Reduced oxygenation | Severe anemia, pneumonia, CHF, CO poisoning |
| Vasospasm | Prinzmetal angina, cocaine use |
| Small vessel disease | Vasculitis, embolism from valve vegetations |
Risk Factors (MEMORIZE as "THE BIG FIVE + OTHERS"):
| Non-Modifiable | Modifiable |
|---|---|
| Age (male >45, female >55) | Smoking (strongest modifiable RF) |
| Male sex | Hypertension |
| Family history of CAD | Diabetes mellitus |
| Genetic factors | Dyslipidemia (high LDL, low HDL) |
| Obesity | |
| Physical inactivity | |
| Metabolic syndrome | |
| Cocaine use |
Exam tip: Diabetes and smoking are considered the two most powerful independent risk factors for premature CAD.
3. TYPES / CLASSIFICATION
IHD presents as a spectrum of clinical syndromes:
IHD
├── STABLE (CHRONIC) IHD
│ └── Stable Angina Pectoris
│
└── ACUTE CORONARY SYNDROMES (ACS)
├── Unstable Angina (UA)
├── NSTEMI (Non-ST Elevation MI)
└── STEMI (ST Elevation MI)
+ Special types:
├── Vasospastic (Prinzmetal) Angina
├── Chronic IHD with Heart Failure
└── Sudden Cardiac Death (SCD)
| Type | What Happens | Key Feature |
|---|---|---|
| Stable Angina | Fixed stenosis >70%; ischemia on exertion only | Predictable, relieved by rest/nitrates in 1-5 min |
| Unstable Angina | Plaque rupture + non-occlusive thrombus; ischemia at rest | New onset, crescendo pattern, occurs at rest - NO troponin rise |
| NSTEMI | Partial occlusion; subendocardial infarction | Troponin elevated; NO ST elevation on ECG |
| STEMI | Complete occlusion; full-thickness (transmural) infarction | ST elevation + troponin elevation; MEDICAL EMERGENCY |
| Prinzmetal Angina | Coronary vasospasm; can occur in normal arteries | ST elevation during pain, resolves spontaneously |
| Sudden Cardiac Death | Ischemia triggers ventricular fibrillation | Death within 1 hour of symptom onset |
4. PATHOPHYSIOLOGY
Step-by-Step Flowchart:
RISK FACTORS (smoking, hypertension, diabetes, hyperlipidemia)
↓
ENDOTHELIAL INJURY (mechanical, chemical, inflammatory)
↓
ATHEROSCLEROTIC PLAQUE FORMATION
(LDL oxidation → foam cells → fatty streak → fibrous plaque)
↓
┌────────────────┬──────────────────────────┐
↓ ↓ ↓
SLOW OCCLUSION PLAQUE RUPTURE/ VASOSPASM
(>70% stenosis) EROSION (ACS trigger) (Prinzmetal)
↓ ↓ ↓
STABLE ANGINA THROMBUS FORMATION ↓
(ischemia only (platelet activation + ACUTE ISCHEMIA
on exertion) coagulation cascade) ↓
↓
Partial occlusion → NSTEMI/Unstable Angina
Complete occlusion → STEMI
↓
MYOCARDIAL ISCHEMIA (within 1-2 min:
loss of contractile function)
↓
MYOCARDIAL NECROSIS (after 20-40 min
of sustained ischemia: irreversible cell death)
↓
INFARCT EXPANSION → SCAR FORMATION
Coronary Artery Territory Map (Exam-Critical):
| Artery Blocked | Area Infarcted | ECG Leads Affected |
|---|---|---|
| LAD (most common) | Anterior LV + septum | V1-V4 |
| RCA | Inferior LV + posterior wall | II, III, aVF |
| LCX | Lateral LV | I, aVL, V5-V6 |
Critical Stenosis Rule: >70% blockage = symptomatic on exertion (stable angina). >90% blockage = symptoms at rest. Complete occlusion = STEMI.
5. CLINICAL FEATURES
Symptoms:
Classic Anginal Chest Pain (PQRST):
| Feature | Description |
|---|---|
| P - Provocation | Exertion, emotion, cold, heavy meal, sexual activity |
| Q - Quality | Pressure, heaviness, squeezing, tightening, "like an elephant sitting on my chest" |
| R - Radiation | Left arm (ulnar), jaw, neck, back, epigastrium |
| S - Severity | Moderate to severe; described as "discomfort" not sharp pain |
| T - Time | Stable angina: 2-5 min; MI: >20-30 min, does not settle |
Additional Symptoms in MI ("autonomic" symptoms):
- Diaphoresis (sweating) - due to sympathetic activation
- Nausea and vomiting - due to vagal stimulation (especially inferior MI)
- Breathlessness (dyspnea) - due to LV dysfunction / pulmonary edema
- Palpitations - due to arrhythmias
- Syncope / presyncope
- A sense of impending doom ("angor animi")
Signs:
- Anxious, pale, diaphoretic patient
- Tachycardia (compensatory) or bradycardia (vagal - inferior MI)
- Hypotension (if cardiogenic shock or RV infarct)
- S4 gallop (stiff ischemic LV)
- S3 gallop (if LV failure develops)
- Pericardial friction rub (post-MI pericarditis, Day 2-3)
- Levine's sign: Patient clenches fist over sternum to describe pain - classic for angina
Why Key Symptoms Occur:
| Symptom | Mechanism |
|---|---|
| Chest pain | Ischemia releases adenosine, bradykinin, and lactic acid - activates cardiac pain receptors (C-fibers via T1-T5 dermatomes) |
| Left arm radiation | T1-T5 dermatome shared by heart and left arm (referred pain) |
| Jaw pain | Referred along the same afferent pathway |
| Sweating | Sympathetic activation (fight-or-flight response to pain) |
| Breathlessness | LV systolic dysfunction → elevated LVEDP → pulmonary venous congestion |
| Nausea/vomiting | Inferior MI stimulates the vagus nerve (Bezold-Jarisch reflex) |
6. KEY SYMPTOMS THAT SUGGEST THE DIAGNOSIS
Hallmark Symptom:
Central crushing chest pain/pressure, radiating to the left arm, NOT relieved by rest in >20 minutes, associated with sweating and breathlessness = STEMI until proven otherwise
Classic Clinical Clues:
| Feature | Significance |
|---|---|
| Pain worse on exertion, relieved in <5 min by rest | Stable angina |
| Pain at rest, new-onset, or crescendo pattern | ACS (unstable angina / NSTEMI) |
| Pain lasting >20 min, not responding to nitrates | MI |
| Pain with ST elevation on ECG | STEMI - emergency reperfusion needed |
| Epigastric pain + vomiting, bradycardia | Inferior MI (often mistaken for indigestion!) |
| Pain with syncope, hypotension | Cardiogenic shock / RV infarction |
| Levine's sign (fist over sternum) | Highly specific for myocardial ischemia |
Red Flag Findings:
- ST elevation in 2+ contiguous leads on ECG → STEMI, call cath lab immediately
- Troponin elevation → myocardial necrosis confirmed
- New LBBB on ECG → treat as STEMI equivalent
- Hypotension + elevated JVP + clear lungs → RV infarction (do NOT give nitrates!)
- Pulse oximetry <94%, pulmonary edema → cardiogenic shock
- Age >70, diabetic, or female: symptoms may be ATYPICAL (fatigue, dyspnea without chest pain - "silent MI")
7. LABORATORY INVESTIGATIONS
| Investigation | Expected Finding | Clinical Significance |
|---|---|---|
| ECG | ST elevation (STEMI), ST depression / T-wave inversion (NSTEMI/UA), Q waves (old MI), new LBBB | Gold standard for rapid diagnosis; done within 10 min of arrival |
| Troponin I or T (high-sensitivity) | Elevated (rises 3-4h, peaks 24h, remains elevated 7-14 days) | Most sensitive and specific marker for myocardial necrosis; serial measurements at 0h and 1-3h |
| CK-MB | Elevated (rises 3-6h, peaks 18-24h, returns to normal in 48-72h) | Earlier return to normal helps detect reinfarction |
| Myoglobin | Elevated earliest (rises within 1-2h) | Very early marker but non-specific; good negative predictive value |
| LDH (LDH1 > LDH2) | Elevated (peaks 3-6 days, lasts 7-10 days) | Useful in late presenters (>24h); "flipped LDH ratio" |
| CBC | Leukocytosis (neutrophilia) within 24-48h | Inflammatory response to necrosis; WBC may reach 12,000-15,000 |
| ESR / CRP | Elevated | Acute phase response to infarction |
| Fasting lipid profile | Elevated LDL, reduced HDL, elevated TGs | Identifies dyslipidemia as risk factor; LDL target <70 mg/dL post-ACS |
| Blood glucose / HbA1c | May be elevated | Identifies/monitors diabetes; hyperglycemia = poor prognosis |
| Renal function (creatinine, eGFR) | May be elevated in cardiogenic shock | Important before contrast for angiography and before ACE inhibitor dosing |
| Echocardiogram (2D Echo) | Wall motion abnormality (regional), reduced EF, pericardial effusion | Assesses LV function, complications; should be done in all ACS |
| Coronary angiography | Site of occlusion/stenosis visible | Gold standard for diagnosis + guides PCI/CABG; done urgently in STEMI |
| Chest X-ray | Cardiomegaly, pulmonary edema (Kerley B lines, bat-wing opacities) | Assesses for CHF, pulmonary congestion |
| Stress test (exercise ECG / stress echo) | ST depression on exercise, reversible wall motion abnormality | Used in stable angina evaluation when diagnosis uncertain |
Cardiac Biomarker Timeline (Exam Must-Know):
Time after MI: 1h 3h 6h 12h 24h 48h 3d 5d 7d 14d
Myoglobin: ↑↑ ↑↑ ↓ N N N
CK-MB: ↑ ↑↑ ↓↓ N N
Troponin I/T: ↑ ↑↑ ↑↑ ↑↑ ↑ ↑ ↑ ↓ N
LDH: ↑ ↑↑ ↑↑ ↑ ↓
Exam Pearl: Troponin is the single best test for MI. If troponin is elevated = NSTEMI or STEMI. If ECG shows ST elevation + elevated troponin = STEMI.
8. DIFFERENTIAL DIAGNOSIS
| Disease | Similar Features | Differentiating Features |
|---|---|---|
| Stable Angina | Exertional chest pain, radiation | Predictable, lasts <5 min, relieved by rest/nitrates; troponin normal |
| Unstable Angina | Chest pain at rest, similar to STEMI | Troponin NORMAL (no necrosis); no ST elevation; less severe |
| NSTEMI | Similar to UA; chest pain at rest | Troponin ELEVATED; ST depression or T-wave changes (not elevation) |
| STEMI | Severe crushing chest pain, diaphoresis | ST elevation in 2+ leads; troponin markedly elevated; emergency |
| Pulmonary Embolism | Chest pain, dyspnea, tachycardia | Pleuritic pain; hypoxia; D-dimer elevated; CT-PA diagnostic |
| Aortic Dissection | Severe chest pain | Pain is TEARING/RIPPING, radiates to BACK; unequal BP in arms; CXR: wide mediastinum |
| Pericarditis | Chest pain, can be central | Pain is SHARP, PLEURITIC (worse with inspiration), relieved by LEANING FORWARD; saddle-shaped ST elevation in all leads; no troponin elevation (usually) |
| GERD / Esophageal spasm | Central chest pain, radiation | Burning in quality, worse after meals / lying down; relieved by antacids |
| Musculoskeletal pain | Chest pain | Reproducible on palpation (tenderness); pleuritic; no ECG changes |
| Hypertensive urgency | Chest discomfort, elevated BP | No ECG changes typical of MI; chest pain due to LVH |
| Costochondritis | Chest pain | Reproducible, point tenderness at costo-sternal junction |
| Prinzmetal Angina | Chest pain at rest, ST elevation | Typically at rest / at night; ST changes transient, reverse completely; normal coronary angiogram |
9. SHORT CLINICAL CASES
Case 1 - STEMI:
A 58-year-old male with a 20-year history of smoking and type 2 diabetes presents to the emergency department with severe central crushing chest pain radiating to the left jaw and arm for the past 45 minutes. He is diaphoretic, pale, and distressed. BP = 90/60 mmHg. HR = 110/min. ECG shows ST elevation in leads II, III, and aVF. Troponin-I is 4.5 ng/mL (elevated).
Diagnosis: Inferior STEMI (RCA occlusion)
Reasoning:
- Crushing chest pain > 20 minutes + diaphoresis = ACS until proven otherwise
- ST elevation in II, III, aVF = inferior wall MI, territory of the Right Coronary Artery (RCA)
- Elevated troponin confirms myocardial necrosis
- Hypotension = either cardiogenic shock or RV involvement (must check right-sided leads V3R/V4R)
- Action: Activate cath lab immediately for primary PCI within 90 minutes
Case 2 - Stable Angina vs NSTEMI:
A 62-year-old woman with hypertension and high cholesterol presents with 3 episodes of chest tightness over the past week, each lasting 10-15 minutes, occurring at rest. ECG shows T-wave inversions in leads V4-V6. Troponin-I at 0h = 0.08 ng/mL (borderline). Repeat at 3h = 0.25 ng/mL (elevated).
Diagnosis: NSTEMI
Reasoning:
- Episodes at rest (not just exertion) = unstable pattern (not stable angina)
- No ST elevation = not STEMI
- Rising troponin on serial measurement confirms myocardial necrosis = NSTEMI (not UA)
- T-wave inversions in lateral leads suggest LCX territory ischemia
- Action: Dual antiplatelet therapy + anticoagulation + early angiography within 24-72h
10. TREATMENT
A. Non-Pharmacological Treatment
Lifestyle Modifications (applicable to ALL IHD):
- Smoking cessation - most impactful single intervention
- Diet: Mediterranean diet, reduce saturated fats, increase omega-3 fatty acids
- Exercise: 30 min moderate aerobic activity 5x/week (after stable phase)
- Weight reduction: Target BMI 18.5-24.9
- Strict BP control: Target <130/80 mmHg
- Strict glycemic control: HbA1c <7% in diabetics
- Cardiac rehabilitation: Supervised exercise + education post-MI
Procedural / Interventional:
- Primary PCI (Percutaneous Coronary Intervention): Preferred reperfusion in STEMI - angioplasty + stent; target door-to-balloon time ≤90 minutes
- Thrombolysis (fibrinolysis): If PCI not available within 120 min; use Streptokinase or Alteplase within 12h of symptom onset
- CABG (Coronary Artery Bypass Grafting): For left main disease, 3-vessel disease with reduced EF, or failed PCI
B. Pharmacological Treatment
ACUTE STEMI / ACS Management (MONA + More):
| Drug | Drug Group | Mechanism of Action | Indication | Dose | Major Adverse Effects |
|---|---|---|---|---|---|
| Aspirin (DOC - antiplatelet) | COX inhibitor / Antiplatelet | Irreversibly inhibits COX-1 → blocks thromboxane A2 synthesis → reduces platelet aggregation | All ACS (immediate, first-line) | 300 mg loading (chewed), then 75-100 mg/day maintenance | GI bleeding, peptic ulcer |
| Clopidogrel | Thienopyridine (P2Y12 inhibitor) | Irreversibly blocks ADP receptor (P2Y12) on platelets | Dual antiplatelet therapy with aspirin in all ACS (DAPT) | 600 mg loading, then 75 mg/day | Bleeding, TTP (rare) |
| Ticagrelor (preferred over clopidogrel) | P2Y12 inhibitor | Reversibly blocks P2Y12 receptor | NSTEMI/STEMI (preferred in high-risk ACS) | 180 mg loading, then 90 mg BD | Dyspnea, bleeding |
| Prasugrel | P2Y12 inhibitor | Irreversibly blocks P2Y12 | STEMI patients undergoing PCI | 60 mg loading, 10 mg/day | Higher bleeding risk; avoid if prior stroke/TIA |
| Morphine | Opioid analgesic | Analgesia + reduces preload (venodilation) + reduces anxiety | Pain relief in STEMI | 2-4 mg IV, repeat every 5-15 min | Nausea, respiratory depression, hypotension; may delay P2Y12 absorption |
| Oxygen | Supplemental O2 | Increases oxygen delivery | Only if SpO2 <94% | 2-4 L/min via nasal cannula | Vasoconstriction if given unnecessarily |
| Sublingual Nitroglycerine (GTN) | Nitrate | Converted to NO → vasodilation (venous > arterial) → reduces preload + afterload + increases coronary flow | Angina pain relief (all types) | 0.4-0.5 mg sublingual, repeat every 5 min x 3 doses | Headache, hypotension; CONTRAINDICATED in RV infarction, hypotension, recent PDE5 inhibitor use |
| IV Nitroglycerine | Nitrate | As above | Ongoing ischemia, hypertension in ACS, pulmonary edema | 5-10 mcg/min IV, titrate | Hypotension, tachycardia |
| Metoprolol (DOC for beta-blocker) | Beta-1 selective blocker | Reduces HR + contractility → decreases myocardial O2 demand; anti-arrhythmic | All ACS (start within 24h if hemodynamically stable), stable angina | 25-50 mg oral BD (in stable patients); 5 mg IV slowly in select cases | Bradycardia, heart block, bronchospasm (avoid in asthma); Contraindicated in acute decompensated HF, cardiogenic shock |
| Carvedilol | Non-selective beta + alpha-1 blocker | Blocks beta-1, beta-2, alpha-1 receptors | Post-MI with reduced EF (systolic HF) | 3.125 mg BD initially, titrate up | Hypotension, dizziness |
| Unfractionated Heparin (UFH) | Anticoagulant | Activates antithrombin III → inactivates IIa and Xa | All ACS (alongside antiplatelet) | 60 U/kg IV bolus, then 12 U/kg/h infusion (target aPTT 50-70 sec) | Bleeding, HIT (heparin-induced thrombocytopenia) |
| Enoxaparin (LMWH) | Anticoagulant | Mainly inhibits Factor Xa | NSTEMI / STEMI (preferred over UFH in many protocols) | 1 mg/kg SC every 12h (reduce in renal impairment) | Bleeding, less HIT than UFH |
| Alteplase (tPA) | Fibrinolytic (thrombolytic) | Activates plasminogen → breaks down fibrin clot | STEMI when PCI not available within 120 min | 15 mg IV bolus, then 0.75 mg/kg over 30 min, then 0.5 mg/kg over 60 min | Bleeding, intracranial hemorrhage (1%) |
| Streptokinase | Fibrinolytic | Forms complex with plasminogen → activates fibrinolysis | STEMI thrombolysis (older, cheaper agent) | 1.5 million units IV over 60 min | Bleeding, allergic reactions, hypotension; cannot repeat within 5 years |
| Atorvastatin | HMG-CoA reductase inhibitor (Statin) | Reduces LDL synthesis; plaque stabilization; anti-inflammatory | All ACS patients, regardless of baseline LDL (start early, high-intensity) | 40-80 mg/day | Myopathy/rhabdomyolysis, elevated LFTs |
| Ramipril / Lisinopril | ACE Inhibitor | Blocks Ang II → reduces afterload + prevents ventricular remodeling | Post-MI with reduced EF (<40%), anterior MI, diabetes, hypertension | Ramipril: 2.5-5 mg BD; titrate to 10 mg BD | Cough, hyperkalemia, renal impairment, angioedema |
| Losartan / Valsartan | ARB | Blocks AT1 receptor (same downstream effect as ACEi) | ACEi intolerance (cough) | Valsartan 40 mg BD, titrate | Hyperkalemia, renal impairment |
| Eplerenone | Mineralocorticoid receptor antagonist | Blocks aldosterone → reduces cardiac fibrosis and remodeling | Post-MI with EF <40% + diabetes or HF symptoms (within 3-14 days) | 25 mg/day, titrate to 50 mg/day | Hyperkalemia, renal impairment |
| Isosorbide Mononitrate (ISMN) | Long-acting Nitrate | Organic nitrate → NO → vasodilation | Stable angina prevention; chronic IHD | 10-40 mg BD | Headache, tolerance (nitrate-free interval of 8-10h needed) |
| Amlodipine | Calcium channel blocker (DHP) | Blocks L-type calcium channels → vasodilation + reduces afterload | Stable angina (when beta-blockers contraindicated), Prinzmetal angina | 5-10 mg/day | Peripheral edema, flushing |
| Diltiazem / Verapamil | Non-DHP CCB | Rate-lowering CCB → reduces HR + vasodilation | Prinzmetal angina; angina with contraindication to beta-blockers | Diltiazem: 60-120 mg TDS; Verapamil: 80-120 mg TDS | Bradycardia, AV block, constipation; AVOID in HF with systolic dysfunction |
| Ranolazine | Late Na-channel blocker | Reduces intracellular Ca overload → anti-ischemic | Refractory stable angina (add-on) | 500-1000 mg BD | QT prolongation, dizziness |
Drug Summary: What to Use and When
| Scenario | Drugs of Choice |
|---|---|
| Stable Angina - acute relief | Sublingual Nitroglycerine (GTN) |
| Stable Angina - long-term prevention | Beta-blocker (1st line) + Aspirin + Statin + ACEi |
| STEMI - immediate | Aspirin + P2Y12 inhibitor (Ticagrelor preferred) + Anticoagulant + Primary PCI |
| NSTEMI/UA - immediate | Aspirin + Ticagrelor + LMWH + Early angiography |
| Post-MI with low EF | Beta-blocker + ACEi + Eplerenone + Statin |
| Prinzmetal Angina | Calcium channel blocker (Diltiazem/Amlodipine) + Nitrates; AVOID beta-blockers |
| RV Infarction | IV fluids (cautiously) + Avoid nitrates and diuretics |
| Thrombolysis (no PCI) | Alteplase or Streptokinase within 12h of onset |
11. CLINICAL PEARLS
Bedside Clues:
- Levine's sign (fist over sternum) is highly specific for cardiac chest pain
- In inferior MI, always check right-sided leads (V3R, V4R) to rule out RV infarction
- Posterior MI - look for tall R waves and ST depression in V1-V2 (mirror image); use posterior leads V7-V9
- Diaphoresis with chest pain = sympathetic activation = likely cardiac cause
- Patient sitting upright, relieved by leaning forward = pericarditis (not ischemia)
- Silent MIs are common in diabetics and elderly women - only sign may be new onset dyspnea, fatigue, or syncope
High-Yield Exam Facts:
- LAD is called the "widow maker" - its occlusion causes anterior MI, the most lethal
- Door-to-balloon time for STEMI: ≤90 min (PCI center) or ≤120 min (transfer to PCI center)
- Troponin starts rising at 3-4 hours and stays elevated for up to 14 days
- LBBB + chest pain = treat as STEMI (Sgarbossa criteria)
- Posterior MI is the most commonly missed MI on standard 12-lead ECG
- Nitrates are absolutely contraindicated in RV infarction (hypotension will worsen) and within 24-48h of PDE5 inhibitor use (sildenafil, tadalafil)
- Q waves on ECG = old (transmural) infarction; appear after 6-12h, persist permanently
- Dressler's syndrome: autoimmune pericarditis 2-10 weeks after MI; treat with aspirin/NSAIDs
Viva Points:
- "What causes pain in angina?" → Accumulation of adenosine, bradykinin, lactic acid stimulating cardiac afferents
- "Why does pain radiate to the arm?" → Referred pain via shared T1-T5 dermatomes
- "What is the earliest ECG change in MI?" → Hyperacute T-waves (peaked T-waves) before ST elevation
- "What is the most specific marker of MI?" → Troponin I and T
- "What is the zone of injury, ischemia, and infarction?" → Injury = ST elevation; Ischemia = T-wave inversion; Infarction = Q waves
- "Canadian Cardiovascular Society (CCS) grading of angina?" → Grade I: angina only with strenuous activity; Grade II: slight limitation; Grade III: marked limitation; Grade IV: angina at rest
12. COMMON DIAGNOSTIC MISTAKES
| Mistake | How to Avoid |
|---|---|
| Diagnosing inferior MI as "indigestion" | Always do an ECG in middle-aged patients with epigastric pain + vomiting; inferior MI can perfectly mimic GI symptoms |
| Missing posterior MI on standard ECG | Always check V7-V9 if V1-V2 shows ST depression with tall R waves + troponin elevation |
| Diagnosing STEMI without posterior leads in inferior MI | Check V3R/V4R for RV infarction before giving nitrates |
| Giving nitrates in RV infarction | Always check right-sided leads in inferior STEMI; hypotension + clear lungs = give IV fluids, not nitrates |
| Not repeating troponin serially | A single normal troponin at presentation does NOT rule out MI; repeat at 1-3h and 6h |
| Mistaking Prinzmetal angina for STEMI | Prinzmetal ST elevation is transient, resolves with nitrates/CCBs; normal coronaries on angiogram |
| Confusing pericarditis with STEMI | Pericarditis: saddle-shaped ST elevation in ALL leads, no reciprocal changes, pain relief with NSAIDs + leaning forward |
| Silent MI in diabetics | Diabetics have autonomic neuropathy; always consider cardiac etiology in unexplained dyspnea or new heart failure in diabetics |
| Missing STEMI equivalent: new LBBB | New or presumably new LBBB with symptoms = activate cath lab, same as STEMI |
| Giving beta-blockers in Prinzmetal angina | Beta-blockers cause unopposed alpha-mediated vasoconstriction and can worsen spasm; use CCBs instead |
| Overlooking drug/cocaine-induced MI | Always ask about cocaine use in young patients with MI; cocaine causes coronary vasospasm AND thrombosis |
13. 5-MINUTE REVISION SUMMARY
DEFINITION
Ischemic Heart Disease = imbalance between myocardial O2 supply and demand,
usually due to coronary artery atherosclerosis.
↓
CAUSES
>90% = atherosclerosis; Risk factors: smoking, diabetes, hypertension,
dyslipidemia, family history, obesity.
↓
PATHOPHYSIOLOGY
Risk factors → endothelial injury → atherosclerotic plaque
→ fixed stenosis (stable angina) OR plaque rupture + thrombus (ACS)
→ myocardial ischemia → necrosis (if >20-40 min sustained)
↓
TYPES
Stable Angina (predictable, on exertion, no troponin rise)
Unstable Angina (at rest/crescendo, no troponin rise)
NSTEMI (at rest, troponin elevated, ST depression/T-wave changes)
STEMI (at rest, troponin elevated, ST elevation → EMERGENCY)
↓
SYMPTOMS
Central crushing chest pain → left arm/jaw/back radiation
+ Diaphoresis + Breathlessness + Nausea
(Atypical in women/elderly/diabetics: only fatigue or dyspnea)
↓
KEY INVESTIGATIONS
ECG (1st thing, within 10 min) → ST elevation = STEMI
Troponin I/T (rises 3-4h, peaks 24h, lasts 14 days) = GOLD STANDARD
Echo = wall motion abnormality + EF assessment
Coronary angiography = definitive diagnosis + guides treatment
↓
TREATMENT
STEMI: Aspirin + Ticagrelor + Anticoagulant + Primary PCI ≤90 min
NSTEMI: Aspirin + Ticagrelor + LMWH + Angiography within 24-72h
Stable Angina: Beta-blocker + Long-acting nitrate + Aspirin + Statin + ACEi
ALL IHD: Lifestyle changes + Statin + Aspirin + ACEi + Beta-blocker post-MI
↓
COMPLICATIONS
Early (0-72h): Arrhythmias (VF most common cause of death), cardiogenic shock,
RV failure, cardiac rupture (Day 3-7)
Late (weeks): Dressler's syndrome (pericarditis), LV aneurysm,
mural thrombus + embolism, chronic heart failure
Teaching note: The single most important concept in IHD management is TIME. Time is muscle. Every 30 minutes of delay in PCI = ~10% additional mortality increase. Burn this into your clinical instinct.
References: Robbins & Kumar Basic Pathology 10th ed.; Harrison's Principles of Internal Medicine 22nd ed. (2025); Braunwald's Heart Disease 12th ed.; Goldman-Cecil Medicine; Katzung's Basic and Clinical Pharmacology 16th ed.; Washington Manual of Medical Therapeutics.
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