Lymphocytic myocarditis and dilated cardiomyopathy: treatment with immunosuppressive agents.

Thirty-four patients with history of congestive heart failure, dilated cardiomyopathy, and biopsy-proven lymphocytic myocarditis were treated for six months with immunosuppressive agents (prednisone and azathioprine) in addition to standard therapy for congestive heart failure. Seventy-three percent had improvement or resolution of the lymphocytic infiltrate, whereas 27% had persistent infiltrates. Improvement in myocardial histologic findings was unpredictable and did not correlate with age, gender, duration of symptoms, initial functional class, severity of left ventricular dysfunction, intensity of initial inflammatory infiltrate, or degree of myocardial cell injury. Histologic response was associated with significant improvement in left ventricular ejection fraction, but not cardiothoracic ratio, left ventricular dimensions, or survival. Functional class improved equally whether patients' disease did or did not respond to the treatment, and was not necessarily associated with objective improvement in cardiac function. Immunosuppressive therapy resulted in serious or fatal side effects in 24% of patients. Overall long-term survival was 79% at one year and 76% at two years. Poor survival was related to left ventricular ejection fraction less than 20%, male sex, age less than 50 years, and marked left ventricular dilation, but not to myocardial histologic findings. These findings indicate that the potential benefits nu the risks of immunosuppressive therapy must be weighed carefully in the individual patient.