Infective endocarditis in intravenous drug abusers: patterns of presentation and long-term outcomes of surgical treatment

BACKGROUND AND AIM OF THE STUDY: Few data exist on infective endocarditis (IE) in intravenous drug abuse (IVDA) patients. In particular, clinical features, site of involvement and bacteriologic findings are controversial. Little is also known on the results of surgical treatment and on the long-term prognosis. METHODS: The clinical and microbiological characteristics of IE in a series of 39 IVDA patients were retrospectively assessed and compared to those in 85 non-IVDA patients with a likely similar life expectancy. The total follow up of patients was 717.6 patient-years (119.9 pt-yr for IVDA, 597.7 pt-yr for non-IVDA). RESULTS: Although tricuspid involvement was significantly more frequent in IVDA cases than in non-IVDA cases (p = 0.001), left-sided endocarditis prevailed in both groups. In addition to Staphylococcus aureus (51.3%), Staph. epidermidis (15.4%) and streptococcal spp. (23.1%) were emerging pathogens in IVDA cases. A worse cardiac function (p < 0.002) and a higher rate of embolism (p = 0.04) characterized the preoperative status of IVDA patients. No difference was observed as to indications, emergency procedures and pathologic findings. Hospital and long-term survival did not significantly differ between the two groups. The rate of recurrence was higher in IVDA cases; this difference was mostly accounted for by early postoperative events. CONCLUSION: A new pattern of IE in IVDA is emerging, characterized by more frequent left heart involvement (61.5%), a severe clinical course, and a need for surgery in the active phase. Staph. epidermidis and streptococci are emerging pathogens. Drug abuse does not affect postoperative prognosis when an aggressive surgical attitude is combined with prolonged medical therapy. Higher rates of early recurrence are expected during the follow up period.