Evaluation of aspirin platelet inhibition in left ventricular assist device population.

INTRODUCTION: Aspirin therapy is recommended in durable left ventricular assist device (LVAD) patients to prevent thromboembolic complications. Up to 30% of patients treated with aspirin may demonstrate aspirin resistance, which has been related to thrombotic complications. However, it is unknown whether individual patients exhibit temporal alterations in aspirin sensitivity during LVAD support. We hypothesized that aspirin platelet inhibition would wane after the initial postimplant period. METHODS: This was a retrospective, observational, single center study conducted at an academic medical center. This study evaluated changes in aspirin platelet inhibition over the first 6 months of LVAD support. Patients who underwent placement of centrifugal LVAD with aspirin platelet sensitivity assays were included for analysis. Aspirin responsiveness was assessed postimplant after 5 days, 3 months, and 6 months. RESULTS: A total of 28 patients were included for analysis of which 7% of patients were aspirin resistant initially. At 3 months, 32% (odds ratio [OR], 6.1, p = .03) of patients were aspirin resistant and 28% (OR, 4.1, p = .1) at 6 months. Over the first 3 months postimplant, the odds of aspirin resistance increased sixfold and remained relatively constant at 6 months. Patients who were aspirin resistant and received an increase in aspirin dose at 3 months subsequently had a sensitive ARU at 6 months. CONCLUSION: Aspirin responsiveness not only varies between patients but can significantly wane within individual LVAD patients over time. Additional study is needed to determine if monitoring aspirin resistance may prevent thrombotic complications after LVAD implantation.