Mortality in primary and secondary myocarditis.

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