3.2 Ischemic Heart Disease, Acute Coronary Syndromes, & Heart Failure Management

3.2 Ischemic Heart Disease, Acute Coronary Syndromes, & Heart Failure Management

Quick Summary: Acute Coronary Syndrome (ACS) mandates rapid triage with 12-lead ECG within 10 minutes. STEMI requires emergency primary PCI within 90 minutes (or thrombolysis within 30 minutes if PCI transfer time >120 minutes). Dual Antiplatelet Therapy (DAPT) with ASA plus Ticagrelor/Prasugrel is preferred in ACS. Chronic Heart Failure with Reduced Ejection Fraction (HFrEF, LVEF ≤40%) requires mortality-reducing Quad Therapy: ARNI, Beta-blocker, MRA, and SGLT2 inhibitor.

Stable Ischemic Heart Disease (SIHD)

Stable ischemic heart disease presents as predictable chest discomfort provoked by exertion or emotional stress and relieved by rest or sublingual nitroglycerin within 5 minutes.

Diagnostic Evaluation & Risk Stratification

1. Baseline Workup: Resting 12-lead ECG, fasting lipids, HbA1c, serum creatinine, and transthoracic echocardiogram (TTE) to assess LV function and valvular anatomy.
2. Non-Invasive Diagnostic Testing:
   • Exercise Stress Test (Treadmill ECG): Indicated for patients with intermediate pre-test probability, capable of exercise, and having a normal baseline ECG.
   • Stress Imaging (Stress Echocardiography or Nuclear Myocardial Perfusion Imaging [MPI]): Indicated if baseline ECG is non-diagnostic (e.g., LBBB, ST-segment depression >1 mm, LVH, digitalis effect) or if patient is unable to exercise (pharmacological stress with dobutamine, dipyridamole, adenosine, or regadenoson).
   • Coronary Computed Tomography Angiography (CCTA): Preferred non-invasive anatomical test in low-to-intermediate probability patients without prior known CAD.
   • Invasive Coronary Angiography: Gold standard; indicated in high-risk non-invasive test results, persistent refractory angina despite medical therapy, or cardiac arrest survivors.

Pharmacological Management

• Symptom Relief: Sublingual Nitroglycerin (0.4 mg SL q5min up to 3 doses for acute angina) + Beta-blockers (first-line anti-anginal; titrate to resting HR 55–60 bpm). Long-acting Calcium Channel Blockers (Dihydropyridine e.g., Amlodipine, or Non-dihydropyridine e.g., Diltiazem if LVEF normal) or Long-acting Nitrates (Isosorbide mononitrate) are added if beta-blockers are insufficient or contraindicated.
• Disease-Modifying / Secondary Prevention:
  • ASA 81 mg daily (or Clopidogrel 75 mg daily if ASA intolerant).
  • High-Intensity Statin (Atorvastatin 80 mg or Rosuvastatin 40 mg daily).
  • ACE Inhibitor or ARB (Mandatory if LVEF ≤40%, hypertension, diabetes, or CKD).

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Acute Coronary Syndromes (ACS)

ACS encompasses STEMI (ST-elevation MI), NSTEMI (Non-ST-elevation MI), and Unstable Angina (UA). NSTEMI and UA are collectively termed NSTE-ACS; NSTEMI is distinguished from UA by elevated cardiac biomarkers (high-sensitivity cardiac troponin).

Acute STEMI Management & Reperfusion Benchmarks

STEMI criteria: New ST-segment elevation at the J-point in ≥2 anatomically contiguous leads (≥1 mm in limb leads; ≥1.5–2.5 mm in precordial leads V2–V3 based on sex/age) or new LBBB with ischemic symptoms.

• Primary Percutaneous Coronary Intervention (PCI): Preferred reperfusion strategy. Target Door-to-Balloon time ≤90 minutes at a PCI-capable center. If presenting at a non-PCI center, transfer for primary PCI if first medical contact to PCI balloon inflation can be achieved within ≤120 minutes.
• Fibrinolytic Therapy: Indicated if primary PCI cannot be delivered within 120 minutes and symptom duration is <12 hours. Target Door-to-Needle time ≤30 minutes using IV Tenecteplase (TNK-tPA). Following fibrinolysis, emergency transfer to a PCI center for rescue PCI (if failed lysis) or routine angiography within 3 to 24 hours is mandatory.

Absolute Contraindications to Thrombolysis: Prior intracranial hemorrhage at any time; known structural cerebrovascular lesion or malignant intracranial neoplasm; ischemic stroke within 3 months; suspected aortic dissection; active internal bleeding (excluding menses); significant closed-head or facial trauma within 3 months.

NSTE-ACS Risk Stratification & Invasive Timing

• Urgent Invasive (<2 hours): Hemodynamic instability, cardiogenic shock, refractory chest pain, life-threatening arrhythmias, or acute heart failure.
• Early Invasive (<24 hours): Temporal rise/fall in cardiac troponin, dynamic ST/T-wave changes, GRACE risk score >140, or LVEF <40%.

Medical Therapy for ACS (MONA-BASH Paradigm)

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Heart Failure Management (CCS 2021/2024 Guidelines)

Heart failure is classified by Left Ventricular Ejection Fraction (LVEF): HFrEF (LVEF ≤40%), HFmrEF (LVEF 41–49%), and HFpEF (LVEF ≥50%).

Guideline-Directed Medical Therapy (GDMT) Quad Therapy for HFrEF

All four foundational drug classes must be initiated and up-titrated promptly to target doses in all HFrEF patients unless contraindicated:

1. Angiotensin Receptor-Neprilysin Inhibitor (ARNI): Sacubitril / Valsartan
   • Preferred over ACEi or ARB due to superior reduction in all-cause and CV mortality (PARADIGM-HF trial).
   • Mandatory Safety Rule: When switching from an ACE inhibitor to Sacubitril/Valsartan, a 36-hour washout period is strictly required to prevent severe, life-threatening angioedema. (No washout required when switching from an ARB).
2. Evidence-Based Beta-Blocker: Bisoprolol, Carvedilol, or Metoprolol Succinate
   • Initiate low and titrate slowly once patient is clinically euvolemic. Avoid atenolol or short-acting metoprolol tartrate.
3. Mineralocorticoid Receptor Antagonist (MRA): Spironolactone (12.5–50 mg daily) or Eplerenone
   • Reduces mortality and HF hospitalizations. Monitor serum K+ and eGFR; hold if K+ >5.5 mmol/L or eGFR <30 mL/min/1.73m².
4. SGLT2 Inhibitor: Dapagliflozin (10 mg daily) or Empagliflozin (10 mg daily)
   • Reduces cardiovascular mortality and HF hospitalizations in HFrEF and HFpEF, regardless of whether the patient has diabetes mellitus.

Loop Diuretics (Furosemide): Administered for symptom relief of congestion and volume overload. Diuretics do not reduce all-cause mortality; doses should be adjusted dynamically based on fluid status.

Advanced Devices in HFrEF

• Implantable Cardioverter-Defibrillator (ICD): Primary prevention of sudden cardiac death in patients with ischemic or non-ischemic cardiomyopathy, LVEF ≤35%, NYHA Class II–III symptoms despite ≥3 months of optimal GDMT, and expected survival >1 year.
• Cardiac Resynchronization Therapy (CRT-P / CRT-D): Indicated for sinus rhythm, LVEF ≤35%, NYHA Class II–IV despite GDMT, and Left Bundle Branch Block (LBBB) with QRS duration ≥130–150 ms.

Acute Decompensated Heart Failure (ADHF)

ADHF evaluation relies on the Forrester Hemodynamic Matrix based on Perfusion (Warm vs. Cold) and Congestion (Dry vs. Wet):

• Warm & Wet (Most Common): Adequate perfusion, elevated filling pressures (orthopnea, JVP elevation, crackles, peripheral edema). Management: IV Loop Diuretics (furosemide IV dose equivalent to 1–2.5x oral daily dose) + IV Vasodilators (Nitroglycerin infusion) if SBP is normal or high.
• Cold & Wet (Cardiogenic Shock): Hypoperfusion (cool extremities, oliguria, altered sensorium, narrow pulse pressure) + Congestion. Management: Inotropes (Dobutamine or Milrinone) ± Vasopressors (Norepinephrine if SBP <90 mmHg) + IV loop diuretics once perfusion is restored + emergency mechanical circulatory support (IABP, Impella, ECMO).

Exam Traps & Special Scenarios

• Inferior Wall MI & RV Infarction: Inferior MI (ST elevation in II, III, aVF) associated with right ventricular infarction (ST elevation in right-sided V4R lead). Presents with hypotension, clear lungs, and elevated JVP. Nitrates, Morphine, and Diuretics are strictly CONTRAINDICATED due to severe preload dependence; treat hypotension with IV Normal Saline fluid boluses.