Chronic antiplatelet therapy and mortality among patients with infective endocarditis

Whether antiplatelet therapy is associated with better outcomes among patients with infective endocarditis (IE) remains controversial. A retrospective study was conducted concerning all patients with IE, treated in a tertiary-care centre of Canada between 1991 and 2006, who satisfied the modified Duke criteria for a definite or possible IE. The primary outcome was all-cause mortality within 90 days of diagnosis. A secondary outcome was the development of major systemic embolism. In total, 241 patients satisfied the inclusion criteria, 75 of whom had been on chronic antiplatelet therapy prior to developing endocarditis. Seventy-one (29.5%) patients died. According to multivariate analysis, age, a high Charlson score, aortic valve involvement, myocardial infarction and presence of a perivalvular abscess were strongly associated with mortality. Undergoing valvular replacement (adjusted OR (AOR) 0.28, 95% CI 0.09-0.84) and chronic antiplatelet therapy before IE (AOR 0.27, 95% CI 0.11-0.64) correlated with lower mortality. There was a trend for lower mortality among patients started on antiplatelet drugs after admission (AOR 0.29, 95% CI 0.08-1.13). The effect of aspirin on mortality was much the same in patients who received 325 or 80 mg daily. Chronic antiplatelet therapy was not associated with a significantly lower risk of major embolism. In conclusion, chronic antiplatelet therapy was associated with lower mortality among patients with IE, independently of any effect on major embolism. Whether or not a beneficial effect could be replicated by initiating antiplatelet therapy at the time of diagnosis remains unproven.