Cardiology · Heart Failure
The facts most likely to be tested
Dilated cardiomyopathy presents as systolic heart failure with eccentric hypertrophy and ventricular dilation leading to a reduced left ventricular ejection fraction (LVEF).
The most common identifiable cause of dilated cardiomyopathy is coronary artery disease (ischemic cardiomyopathy), while non-ischemic causes include alcohol abuse, viral myocarditis (Coxsackievirus), and doxorubicin toxicity.
Physical examination typically reveals an S3 gallop, displaced apical impulse, and signs of biventricular failure such as jugular venous distension and peripheral edema.
Echocardiography is the diagnostic test of choice, demonstrating four-chamber dilation and global hypokinesis.
Genetic causes of dilated cardiomyopathy are frequently linked to mutations in the TTN gene (encoding titin), which is the most common familial etiology.
Pharmacologic management to improve survival includes ACE inhibitors (or ARNI), beta-blockers (specifically carvedilol, metoprolol succinate, or bisoprolol), and mineralocorticoid receptor antagonists.
Patients with a persistent LVEF ≤ 35% despite optimal medical therapy are candidates for an implantable cardioverter-defibrillator (ICD) to prevent sudden cardiac death.
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A 54-year-old male presents with progressive dyspnea on exertion and orthopnea over the past three months. He has a history of heavy alcohol consumption and hypertension. On physical exam, his blood pressure is 105/65 mmHg, and he has bilateral pitting edema to the knees. Cardiac auscultation reveals a displaced point of maximal impulse and an S3 gallop. An echocardiogram shows global hypokinesis and a left ventricular ejection fraction of 25%.
What is the most appropriate long-term pharmacologic management to improve survival in this patient?
Initiation of an ARNI (sacubitril/valsartan), a beta-blocker, and a mineralocorticoid receptor antagonist.
The patient presents with classic signs of dilated cardiomyopathy; the standard of care for HFrEF to improve mortality includes the 'triple therapy' of ARNI/ACEi, beta-blockers, and MRAs as outlined in the bets.
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Etiology / Epidemiology
Most common cardiomyopathy; caused by idiopathic factors, alcohol abuse, or viral myocarditis.
Clinical Manifestations
Presents as systolic heart failure with S3 gallop and displaced apical impulse.
Diagnosis
Gold standard is Echocardiogram showing LVEF <40% and ventricular dilation.
Treatment
First-line is ACE inhibitors and Beta-blockers; avoid NSAIDs in heart failure.
Prognosis
High risk of sudden cardiac death; consider ICD if LVEF remains ≤35%.
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Epidemiology & Etiology
Most cases are idiopathic, but secondary causes include chronic alcohol use, Coxsackie B virus, and doxorubicin toxicity. Genetic mutations in the TTN (titin) gene are increasingly recognized. It is the most common indication for cardiac transplantation.
Pertinent Anatomy
Characterized by left ventricular dilation and thinning of the ventricular walls. The resulting geometry leads to mitral regurgitation due to annular stretching. The heart appears globular on imaging.
Pathophysiology
Myocardial injury leads to ventricular remodeling and progressive dilation. This results in systolic dysfunction (reduced contractility) and decreased ejection fraction. The compensatory activation of the RAAS system eventually worsens fluid overload and myocardial stress.
Clinical Manifestations
Patients present with dyspnea on exertion, orthopnea, and paroxysmal nocturnal dyspnea. Physical exam reveals a displaced point of maximal impulse, S3 gallop, and peripheral edema. Syncope or palpitations are red flags for ventricular arrhythmias.
Diagnosis
The Echocardiogram is the diagnostic test of choice, demonstrating LVEF <40% and global hypokinesis. Cardiac MRI is useful for identifying underlying fibrosis or infiltrative disease. BNP levels are typically elevated, reflecting ventricular wall stretch.
Treatment
Management focuses on ACE inhibitors and Beta-blockers (specifically carvedilol, metoprolol succinate, or bisoprolol) to reduce mortality. Loop diuretics are used for symptomatic volume overload. NSAIDs and calcium channel blockers (non-dihydropyridines) are contraindicated as they worsen heart failure.
Prognosis
Prognosis is poor, with a 5-year mortality rate near 50% in symptomatic patients. Sudden cardiac death is a major risk, necessitating an ICD for patients with persistent LVEF ≤35% despite optimal medical therapy.
Differential Diagnosis
Ischemic Cardiomyopathy: presence of coronary artery disease on angiography
Hypertrophic Cardiomyopathy: asymmetric septal hypertrophy on echo
Restrictive Cardiomyopathy: normal wall thickness with diastolic dysfunction
Myocarditis: acute onset with fever and elevated troponins
Valvular Heart Disease: primary structural abnormality of valves