A 58-year-old man with a 10-year history of hypertension presents with progressive dyspnea on exertion and orthopnea. Echocardiography shows left ventricular hypertrophy with reduced ejection fraction. What is the most common cause of heart failure in this patient?

Explanation

## Most Common Cause of Heart Failure with Reduced Ejection Fraction (HFrEF) ### Epidemiology and Prevalence **Key Point:** Coronary artery disease (CAD) is the most common cause of heart failure with reduced ejection fraction (HFrEF) in developed countries, accounting for approximately 60–70% of cases of systolic heart failure (Harrison's Principles of Internal Medicine, 21st ed.). **High-Yield:** While hypertension is the most common *risk factor* and a leading cause of heart failure overall (particularly diastolic/HFpEF), CAD — through ischemic cardiomyopathy and post-MI ventricular remodeling — is the predominant etiology when the ejection fraction is specifically reduced. ### Mechanism of CAD-Induced HFrEF 1. Myocardial ischemia → cardiomyocyte loss and necrosis 2. Post-infarction ventricular remodeling → chamber dilation 3. Progressive systolic dysfunction → reduced ejection fraction 4. Compensatory neurohormonal activation (RAAS, SNS) → further remodeling 5. Overt heart failure with reduced EF (ischemic cardiomyopathy) ### Clinical Context in This Patient The patient has: - Long-standing hypertension (10 years) — a major risk factor for CAD - **Reduced ejection fraction** — hallmark of systolic/ischemic HF - LVH on echocardiography — consistent with hypertensive remodeling but also seen in ischemic disease - Classic HF symptoms (DOE, orthopnea) The explicit finding of **reduced ejection fraction** shifts the most likely etiology toward CAD (ischemic cardiomyopathy), as hypertension more classically causes HFpEF (preserved EF) in its early stages. ### Comparative Frequency of HF Causes | Cause | HFrEF Frequency | Key Feature | |-------|----------------|-------------| | **CAD / Ischemic cardiomyopathy** | **60–70%** | **Most common cause of HFrEF** | | Hypertension | 10–20% | More commonly causes HFpEF; major risk factor | | Idiopathic/Dilated cardiomyopathy | 10–15% | Diagnosis of exclusion | | Valvular heart disease | 5–10% | Specific valve lesions; hemodynamic burden | **Clinical Pearl:** Hypertension is the most common *risk factor* for heart failure and the most common cause of HFpEF, but CAD (ischemic cardiomyopathy) is the most common cause of HFrEF. When the question specifies a **reduced ejection fraction**, CAD must be recognized as the leading etiology (Harrison's, 21st ed.; Braunwald's Heart Disease, 12th ed.). ### Why CAD Is the Correct Answer The stem explicitly states **reduced ejection fraction**, which defines HFrEF. In this context, CAD-related ischemic cardiomyopathy is the most common cause. Hypertension, while present and contributory, is a risk factor that more typically produces diastolic dysfunction (HFpEF). The combination of hypertension as a risk factor and reduced EF strongly points to ischemic cardiomyopathy as the underlying etiology.