Injection Drug Use and Outcomes After Surgical Intervention for Infective Endocarditis

Infective endocarditis (IE) requiring surgical intervention in patients who actively inject drugs poses treatment challenges. Decisions regarding the need for operation are affected by concern for relapse of IE from ongoing injection drug use (IDU). The purpose of this study was to evaluate the effect of active IDU on outcomes after operation for IE.

All patients with IE surgically treated at Cleveland Clinic from July 1, 2007 to July 1, 2012 were identified from the Cleveland Clinic Infective Endocarditis Registry and the Cardiovascular Information Registry. Of 536 patients operated on for IE during the study period, 41 (8%) actively injected drugs. The primary outcome of the study was death or reoperation for IE.

Patients who injected drugs had poorer survival free of reoperation, and the risk of events varied with time. In a multivariable Cox proportional hazards model, using time-dependent covariates, IDU was associated with a higher hazard of death or reoperation between 90 and 180 days (hazard ratio [HR], 9.8; 95% confidence interval [CI], 2.7-35.3) but not before 90 days (HR, 0.38; 95% CI, 0.05-3.1) or after 180 days (HR, 1.8; 95% CI, 0.8-3.8). Among patients who injected drugs, reoperation and death contributed equally to the outcome, whereas among patients who did not inject drugs, reoperation for IE was far less common.

Between 3 and 6 months after operation for IE, patients who inject drugs have a hazard of death or reoperation that is about 10 times that of patients who do not inject drugs. Before and after, the HRs are much smaller and not statistically significant.