2.1 Coronary Artery Disease, Dysrhythmias & Heart Failure
Key Takeaways
- Primary PCI is the treatment of choice for STEMI if it can be performed within 90 minutes of first medical contact; otherwise, fibrinolysis within 30 minutes is indicated.
- Guideline-directed medical therapy (GDMT) for HFrEF includes a beta-blocker, ARNI/ACEi, MRA, and an SGLT2 inhibitor to reduce mortality.
- Non-valvular atrial fibrillation requires anticoagulation based on the CHA2DS2-VASc score; DOACs are preferred over warfarin in most patients.
- In patients with narrow-complex regular tachycardia (e.g., SVT), vagal maneuvers and adenosine are first-line therapies.
- High-intensity statin therapy (e.g., Atorvastatin 40-80 mg or Rosuvastatin 20-40 mg) is indicated for all patients with clinical ASCVD regardless of baseline LDL-C.
1. Coronary Artery Disease and Acute Coronary Syndromes (ACS)
Coronary artery disease (CAD) remains a leading cause of morbidity and mortality globally, and its prevalence in Saudi Arabia is markedly elevated due to high rates of metabolic syndrome, diabetes mellitus, and sedentary lifestyles. ACS encompasses a spectrum of conditions ranging from Unstable Angina (UA) to Non-ST-Segment Elevation Myocardial Infarction (NSTEMI) and ST-Segment Elevation Myocardial Infarction (STEMI).
Pathophysiology and Clinical Presentation
ACS is primarily driven by the rupture or erosion of an atherosclerotic plaque, leading to platelet aggregation, thrombus formation, and subsequent myocardial ischemia. Patients typically present with retrosternal chest pain (often described as crushing or pressure-like) radiating to the left arm, neck, or jaw, accompanied by diaphoresis, nausea, and dyspnea. Atypical presentations (e.g., epigastric pain, unexplained fatigue, or isolated dyspnea) are more common in women, the elderly, and diabetic patients.
Diagnosis and ECG Localization
The 12-lead ECG is the cornerstone of initial evaluation and must be obtained within 10 minutes of arrival. STEMI is characterized by ST-segment elevation of ≥ 1 mm in two contiguous leads (≥ 2 mm in V2-V3 for men ≥ 40 years, ≥ 2.5 mm for men < 40, and ≥ 1.5 mm for women).
ECG Localization of Infarction:
- Anterior (V1-V4): Left Anterior Descending (LAD) artery.
- Lateral (I, aVL, V5-V6): Left Circumflex (LCx) artery or Diagonal branch of LAD.
- Inferior (II, III, aVF): Right Coronary Artery (RCA) in 80% of patients; LCx in 20%.
- Right Ventricular (V4R): Proximal RCA. (Caution: Avoid nitrates due to preload dependence).
- Posterior (ST depression in V1-V3): RCA or LCx.
Cardiac troponins (preferably high-sensitivity troponin) are essential for differentiating NSTEMI from Unstable Angina, but treatment for STEMI should never be delayed while waiting for biomarker results.
Management Algorithms
Initial therapy for all ACS patients involves the mnemonic MONA (Morphine, Oxygen if SpO2 < 90%, Nitroglycerin, Aspirin). Dual antiplatelet therapy (DAPT) with Aspirin and a P2Y12 inhibitor (Ticagrelor or Prasugrel are preferred over Clopidogrel) is critical.
STEMI Management: Reperfusion therapy is time-critical. Primary Percutaneous Coronary Intervention (PCI) is the gold standard if door-to-balloon time is < 90 minutes (or < 120 minutes if transferred from a non-PCI capable center). If PCI cannot be performed within this timeframe, fibrinolysis (e.g., Tenecteplase, Alteplase) should be administered within 30 minutes of arrival, provided there are no absolute contraindications (e.g., prior intracranial hemorrhage, active bleeding).
NSTEMI/UA Management: Patients are risk-stratified using scores like GRACE or TIMI. High-risk patients (e.g., hemodynamic instability, dynamic ST changes, elevated troponins) require an early invasive strategy (angiography within 24 hours).
2. Cardiac Dysrhythmias
Prompt recognition of arrhythmias via ECG is frequently tested on the SMLE.
Atrial Fibrillation (AFib)
AFib is an irregularly irregular rhythm with absent P waves. Management focuses on rate control, rhythm control, and stroke prevention.
- Rate Control: Beta-blockers (e.g., Metoprolol) or non-dihydropyridine CCBs (Diltiazem, Verapamil) are first-line.
- Stroke Prevention: The CHA2DS2-VASc score dictates anticoagulation. A score of ≥ 2 in men or ≥ 3 in women mandates anticoagulation. Direct Oral Anticoagulants (DOACs like Apixaban, Rivaroxaban) are preferred over Warfarin for non-valvular AFib due to a lower risk of intracranial bleeding and no need for routine INR monitoring. Warfarin remains indicated for mechanical heart valves or moderate-to-severe mitral stenosis.
Supraventricular Tachycardia (SVT)
SVT presents as a narrow-complex, regular tachycardia (rate typically 150-250 bpm). In stable patients, vagal maneuvers (e.g., Valsalva) are attempted first, followed by rapid IV Adenosine. If the patient is hemodynamically unstable, synchronized cardioversion is immediately indicated.
Ventricular Arrhythmias
- Ventricular Tachycardia (VT): Wide-complex tachycardia. If stable, antiarrhythmics like Amiodarone can be used. If unstable with a pulse, synchronized cardioversion is required. Pulseless VT requires immediate defibrillation.
- Ventricular Fibrillation (VF): Chaotic, irregular, wide complexes. Management requires immediate high-quality CPR and defibrillation as per ACLS protocols.
3. Heart Failure
Heart failure is categorized based on the Left Ventricular Ejection Fraction (LVEF): Heart Failure with Reduced Ejection Fraction (HFrEF; LVEF ≤ 40%) and Heart Failure with Preserved Ejection Fraction (HFpEF; LVEF ≥ 50%).
Pathophysiology and Presentation
HFrEF involves a primary failure of contractility (systolic dysfunction), often secondary to ischemic heart disease or dilated cardiomyopathy. HFpEF involves impaired relaxation (diastolic dysfunction), typically driven by long-standing hypertension, left ventricular hypertrophy, and aging. Patients present with dyspnea on exertion, orthopnea, paroxysmal nocturnal dyspnea (PND), elevated jugular venous pressure (JVP), and peripheral edema.
Guideline-Directed Medical Therapy (GDMT) for HFrEF
The cornerstone of HFrEF management involves medications that improve survival and reverse cardiac remodeling. The foundational "four pillars" of GDMT include:
- Beta-Blockers: Specifically Carvedilol, Metoprolol succinate, or Bisoprolol. They reduce sympathetic overactivation.
- Angiotensin Receptor-Neprilysin Inhibitors (ARNI) or ACEi/ARBs: Sacubitril/Valsartan (ARNI) is preferred over ACEi to reduce morbidity and mortality.
- Mineralocorticoid Receptor Antagonists (MRAs): Spironolactone or Eplerenone. Careful monitoring of potassium is required.
- SGLT2 Inhibitors: Dapagliflozin or Empagliflozin. Originally diabetes medications, these have profound mortality benefits in HFrEF irrespective of diabetic status.
Diuretics (e.g., Furosemide) are used for symptom relief (volume overload) but do not confer a mortality benefit. Devices such as Implantable Cardioverter-Defibrillators (ICDs) are indicated for primary prevention of sudden cardiac death in patients with LVEF ≤ 35% despite optimized GDMT.
A 65-year-old male presents to the emergency department with severe, crushing substernal chest pain that began 45 minutes ago. His 12-lead ECG demonstrates 3 mm ST-segment elevations in leads V1 through V4. Which of the following coronary arteries is most likely occluded in this patient?
A 72-year-old female with a history of hypertension and type 2 diabetes mellitus is incidentally found to have an irregularly irregular heart rhythm on examination. An ECG confirms atrial fibrillation. Her blood pressure is 135/85 mmHg and heart rate is 88 bpm. Which of the following is the most appropriate long-term medication to prescribe for stroke prevention in this patient?
A 58-year-old male with a history of anterior myocardial infarction two years ago is evaluated in the clinic for progressive exertional dyspnea. Echocardiography reveals a left ventricular ejection fraction of 30%. He currently takes only furosemide for ankle swelling. Which of the following medications should be initiated to reduce this patient's long-term mortality risk?