Cardiomyopathy

A 38-year-old man is hospitalized with palpitations and dyspnea. He has no significant medical history and does not take any medications. He has a 20-pack-year smoking history and drinks alcohol daily. He does not use illicit drugs.

On physical examination, temperature is 36.9 °C (98.5 °F), blood pressure is 120/80 mm Hg, and heart rate is 115/min. Jugular venous pressure is normal. The lungs are clear. Cardiac examination shows an irregularly irregular rhythm. There is trace edema at both ankles.

Laboratory Studies
Hemoglobin 14 g/dL
Mean corpuscular volume 101 fL
Aspartate aminotransferase 55 U/L
Alanine aminotransferase 45 U/L
Thyroid-stimulating hormone 4.5 μU/mL

Electrocardiogram shows normal voltage, normal axis, and atrial fibrillation. Echocardiogram shows dilated ventricles with normal wall thickness and severely decreased systolic function (left ventricular ejection fraction, 15%). The patient is started on lisinopril, carvedilol, and warfarin. Later in the hospital course, he spontaneously converts to normal sinus rhythm, he feels well, and has a blood pressure of 105/75 mm Hg and a heart rate of 63/min. Electrocardiogram confirms normal sinus rhythm.

Which of the following is the most likely type of cardiomyopathy in this patient?
A Alcoholic
B Amyloid
C Hypertrophic
D Ischemic

Key Point
Alcoholic cardiomyopathy is a dilated cardiomyopathy.

Answer and Critique (Correct Answer = A)

This patient likely has alcoholic cardiomyopathy, which generally occurs after many years of heavy alcohol consumption, although it may also occur after a short period of heavy consumption. Typically, both ventricles are dilated and globally hypokinetic. The patient reports that he drinks alcohol daily, and his laboratory test results suggest chronic alcohol use (macrocytosis) and possibly an acute episode of heavy alcohol use (mild elevation of aminotransferases, new-onset atrial fibrillation). In addition to medical therapy for heart failure, therapy for alcoholic cardiomyopathy must include total abstinence from alcohol. Abstinence may reverse the cardiomyopathy in patients with less advanced disease.

Cardiac amyloidosis results in increased left ventricular wall thickness due to deposition of amyloid, and, as a result, typically presents with restrictive cardiomyopathy, which is characterized by diastolic rather than systolic dysfunction. On echocardiography, ventricular chambers are typically small with thick walls, and the atria are dilated. Because increased left ventricular wall thickness is caused by infiltration of the myocardium rather than hypertrophy, the electrocardiographic voltage is generally low.

Hypertrophic cardiomyopathy is characterized by inappropriate, marked, and asymmetric hypertrophy of the left ventricle. The hypertrophy usually involves the interventricular septum, although there is a wide range of severity and location of hypertrophy, hemodynamic consequences, and symptoms. The left ventricular cavity is small, unlike the cavity in this patient.

Ischemic cardiomyopathy is often, but not invariably, associated with symptomatic coronary artery disease. The electrocardiogram may show evidence of previous infarction and the echocardiogram typically shows focal, not global, hypokinesis.
Bibliography

1. Piano MR. Alcoholic cardiomyopathy: incidence, clinical characteristics, and pathophysiology. Chest. 2002;121:1638-50. [PMID: 12006456]