Right-sided Endocarditis in Intravenous Drug Users

OBJECTIVE: To describe the clinical, laboratory, and echocardiographic findings in a large group of patients with right-sided endocarditis and to determine whether any of these findings is predictive of prognosis. DESIGN: Retrospective survey of medical records to evaluate the course of hospitalization with follow-up on 6-month survival. Review of two-dimensional echocardiograms by an observer blinded to clinical information. SETTING: Large, metropolitan, voluntary hospital. PATIENTS: One hundred twenty-one intravenous drug users with clinical and bacteriologic evidence of 132 episodes of endocarditis. The presence of a right-sided valvular vegetation detected by two-dimensional echocardiography was required for entry into the study. MEASUREMENTS AND RESULTS: Staphylococcus aureus was the most common infecting organism (82%, 108 of 132). Vegetations involved the tricuspid valve in 127 episodes, the pulmonic in 4, and both in 1; they ranged in size from 0.4 to 4.3 cm (mean, 1.5 +/- 0.7 cm). Vegetations greater than 1.0 cm were present in 106 cases (80%). Among patients with isolated native right-sided endocarditis who reached a definite end point in treatment, mortality was 7% (7 of 98). Vegetations greater than 2.0 cm were associated with a significantly higher mortality compared with vegetations of 2.0 cm or less (33% compared with 1.3%, P less than 0.001). CONCLUSIONS: Overall, right-sided endocarditis has a favorable prognosis. Although complications and prolonged fever are common, most cases respond to medical therapy. Our findings suggest that vegetation size may be an important predictor of outcome and that vegetations greater than 2.0 cm are associated with increased mortality.