Clinical profile of biopsy proven idiopathic myocarditis.

We studied 20 patients in detail (age: 27 months to 45 years, mean 22 years; 15 males, 5 females) of idiopathic myocarditis histologically confirmed by endomyocardial biopsy. None of these patients had evidence of active or previous rheumatic fever. The commonest mode of presentation was congestive heart failure (16 patients) followed by arrhythmias (seven patients--five of whom had associated congestive heart failure) and chest pain resembling myocardial infarction (two patients). Ten patients had a history of preceding upper respiratory infection. Only one of these patients had a significant rising serum titre for Coxsackie B3 virus. Throat and rectal swabs for virus culture were negative in all patients. The electrocardiogram was abnormal in all patients, with a prolonged corrected QT-interval being the commonest abnormality (14 patients). Serial electrocardiographic patterns of evolving myocardial infarction occurred in three patients. Echocardiographic left ventricular end diastolic dimension (4.15 +/- 1.01 cm/m2) and end systolic dimension (3.37 +/- 1.03 cm/m2) were increased in 15 of the 18 patients studied. Pericardial involvement occurred in only one patient. Radionuclide ventriculography showed a reduced left ventricular ejection fraction (< 50%) in 17 patients, global hypokinesia in 12 patients and regional wall motion abnormalities in five patients. Left ventricular and right ventricular end diastolic pressures were elevated in 15 and 11 patients, respectively.