Myocarditis was histologically confirmed by biopsy in 102 pts during a 19 year period. Twenty-two pts (22%) presented with sustained ventricular tachyarrhythmias (SUSVT; monomorphic ventricular tachycardia N=14, cardiac arrest N=8). Of the remaining 80 pts (OTHER), 60 (59%) presented as heart failure, 12 (11%) as myocardial infarction and 8 (8%) as atrioventricular block. There were no differences between SUSVT and OTHER in: gender, atrial arrhythmias, right atrial or pulmonary capillary wedge pressure, cardiac index, ejection fraction, or left ventricular wall motion abnormalities. The following variables differed between groups:VariableSUSVT (N=22)OTHER (N=80)p-valueAge (mean ± SD years)40±1747±150.10Histologic cell typeLymphocytic myocarditis, N, (percent)16(73)74(92)0.01Granulomatous myocarditis, N, (percent)6(27)6(8)0.01Mean LV end-diastolic pressure (mmHg)15±719±80.10Mean NYHA heart failure class1.7±12.3±10.03Any atrioventricular block, N, (percent)10(45)11 (14)0.003Intraventricular conduction defect, N, (percent)13 (60)24(30)0.01Mean OT duration (milliseconds)426±66365±680.001Mean OTc duration (milliseconds)456±44426±620.02Multiple logistic regression revealed 5 variables were independently associated with SUSVT: granulomatous cell type (odds ratio 4.77, P=0.031. mean NYHA heart failure class (odds ratio 0.45, p=0.02), intraventricular conduction defect (odds ratio 4.08, p=0.01), atrioventricular block (odds ratio 5.66, p=0.01) and QT duration (odds ratio 1.01, P=0.01).Life-threatening ventricular arrhythmias are the initial manifestation of myocarditis in nearly 25% of pts. Sustained ventricular tachycardia and cardiac arrest are more likely in myocarditis pts with granulomatous than lymphocytic cell type, milder heart failure symptoms, and more extensive conduction and repolarization abnormalities.