Study Objective: To determine the incidence of myocarditis proved by biopsy findings in patients presenting with unexplained congestive heart failure.
Design: Retrospective review.
Setting: General medical services of a Veterans Administration and university hospital.
Patients: Ninety consecutive patients presenting with unexplained congestive heart failure who had endomyocardial biopsy as a part of their diagnostic evaluation.
Measurements and Main Results: Classification of biopsy findings according to a recently proposed scheme for histologic diagnosis of myocarditis (Dallas criteria) showed myocarditis in only 4 of 90 (4.4%) patients (95% CI, 0.2 to 8.6), although two thirds of the patients had symptoms of congestive heart failure for less than 3 months.
Conclusions: The incidence of myocarditis proved by endomyocardial biopsy findings is low in patients presenting with unexplained congestive heart failure and raises questions concerning the need for this procedure in this patient group.