Lymphocytic myocarditis presents as a primary disorder or in association with a systemic disease. Whether primary and secondary myocarditis have the same prognosis is unknown.

Patients (n = 171) referred to the Johns Hopkins Cardiomyopathy service from 1984 to 1998 with newly diagnosed cardiomyopathy were observed for an average of 5.9 years after an original diagnosis of biopsy-proven myocarditis or until reaching the end point of death. Giant-cell myocarditis was excluded from this study. Myocarditis was classified as secondary when a systemic disease was present at the time of presentation; otherwise, myocarditis was classified as primary. Survival rates among patients with primary and secondary myocarditis were compared with Kaplan-Meier analysis and Cox proportional hazard models incorporating clinical variables, including baseline hemodynamics and treatment with immunosuppressive therapy.

The mortality rate associated with secondary myocarditis varied substantially depending on the underlying systemic disorder. Peripartum myocarditis, when compared with idiopathic myocarditis, had a reduced mortality rate (relative hazard, 0.23 [0.06–0.98]; P <.05), which was attenuated after controlling for confounding variables (relative hazard, 0.62 [0.13–2.98]; P = .55). In contrast, human immunodeficiency virus myocarditis had a particularly poor prognosis (relative hazard, 6.70 [3.51–12.79]; P <.05), even after controlling for confounding variables. Myocarditis associated with systemic inflammatory disorders showed a trend toward increased mortality rate (relative hazard, 2.46 [0.65–9.38]; P = .19). For both primary and secondary myocarditis, advanced age and pulmonary hypertension were important clinical predictors of death.

The prognosis of patients with secondary myocarditis, when compared with patients with idiopathic myocarditis, seems most affected by the primary disease process.