Cardiomyopathies comprise a group of diseases in which the dominant characteristic is primary involvement of heart muscle (myocardium only).
Describe the classification of cardiomyopathy.
Cardiomyopathy can be classified as primary, which is heart muscle disease of unknown etiology, or secondary, which is heart muscle disease in response to specific or preexisting disease (coronary artery disease, hypertension, valvular heart disease, infection, or coexisting disease). However, the World Health Organization has recommended that cardiomyopathy be classified into three major groups according to pathophysiology regardless of etiology:
What is the incidence of idiopathic dilated cardiomyopathy?
0.7-7.5/100,000 population, with higher incidence rates seen in blacks than whites and males than females.
What factors predict increased mortality in patients with dilated cardiomyopathy?
New York Heart Association functional class II or greater Intraventricular conduction delay on electrocardiography Left ventricular end-diastolic pressure 20 mm Hg Cardiac index 3.0 Increased serum norepinephrine level Increased serum level of atrial natriuretic peptide Increased cardiothoracic ratio of 0.55 on chest x-ray Hyponatremia
What are the definite indications for endomyocardial biopsy?
Monitoring cardiac allograft rejection Detecting myocarditis Monitoring anthracycline cardiotoxins Diagnosing secondary cardiomyopathy
What is the major pathophysiological characteristic of dilated cardiomyopathy?
Dilated cardiomyopathy is characterized by biventricular enlargement with reduced ventricular systolic function.
How frequently does cardiomyopathy develop with anthracycline chemotherapeutic agents?
The incidence is 1.7‚ 4.4% depending on which anthracycline agent is used. A clear cumulative dose-related incidence has been found. Patients receiving a cumulative dose of 500-550 mg/m2 of doxorubicin have a 7% incidence of developing cardiomyopathy. Patients receiving a cumulative dose of 550 mg/m2 have a 20-40% incidence of developing cardiomyopathy. If other chemotherapeutic agents, such as mitomycin or cyclophosphamide, and radiation therapy are combined with doxorubicin, cardiomyopathy may develop at a lower cumulative dose (450-500 mg/m2).
Which chemotherapeutic agents most frequently cause cardiomyopathy?
Doxorubicin, cyclophosphamide, amsacrine, and interferon.
Does therapy for dilated idiopathic cardiomyopathy differ from that for congestive heart failure secondary to coronary artery disease?
The approach in treating patients with dilated cardiomyopathy and congestive heart failure are similar. Treatment consists of salt restriction, limitation of physical exertion, diuretics, angiotensin-converting enzyme inhibitors, combination of hydralazine and isosorbide nitrates, digitalis, oral anticoagulants, and 3-blockade.
Name the neuromuscular disorders that are most commonly associated with dilated cardiomyopathy.
Friedreich’s ataxia, myotomic muscular dystrophy, Duchenne muscular dystrophy.