Multivalve infective endocarditis in intravenous drug using patients: an epidemiological study

Infective endocarditis (IE) remains a life-threatening condition. Intravenous drug use (IVDU) adds to the clinical challenge associated with IE due to clinical aberrations caused by the social issues associated with this population.

To improve survival, this study aimed to characterize the contemporary IVDU-associated IE population seen at our tertiary hospital, determine their long-term outcomes and find risk factors associated with mortality.

Retrospective observational cohort study.

A total of 79 patients accounting for 89 presentations were treated for IVDU-associated IE at St Vincent's Hospital Melbourne (SVHM) between 1999 and 2015. Patients were followed-up until death or January 2021. The primary outcome was all-cause mortality and Kaplan-Meier survival analysis was used to calculate long-term survival estimates. Cox proportional hazards analysis was used to examine risk factors for mortality.

The IVDU population treated at SVHM had a high rate of multivalvular IE, at 18.98%. Multivariate analysis revealed that multivalvular IE is significantly associated with an increased risk of mortality in a dose-dependent relationship (two valves affected: HR = 4.73, P = 0.006, three valves affected: HR = 14.19, P = 0.014). The IVDU population has survival estimates of 83.78% (95%CI: 73.21-90.45%) at 1-year and 64.98% (95%CI: 50.94-75.92%) at 15-years.

IVDU patients have high rates of multivalvular endocarditis, which is associated with increased risk of mortality and difficult to identify on echocardiography. Clinicians should be suspicious of multivalve involvement in the IVDU population and decisions related to medical management/intervention should be made with the understanding that these patients are at a higher risk of death.