Platelet reactivity is associated with pump thrombosis in patients with left ventricular assist devices.

Background: Patients with left ventricular assist devices (LVADs) are treated with a potent antithrombotic regimen to prevent pump thrombosis and thromboembolism. High on-treatment residual platelet reactivity (HRPR) is associated with ischemic outcomes in cardiovascular disease.

Objectives: In the current study, we investigated the prevalence and clinical impact of HRPR in stable LVAD patients.

Methods: Pump thrombosis, bleeding events, and death were assessed in 62 LVAD patients (19 HeartWare HVAD [Medtronic] and 43 HeartMate 3 [Abbott]) during a 2-year follow-up. Platelet aggregation was measured by multiple electrode aggregometry, and HRPR was defined as arachidonic acid (AA)-inducible platelet aggregation of ≥21 aggregation units. Soluble P-selectin was determined by enzyme-linked immunosorbent assay.

Results: Three patients (4.8%) had pump thrombosis and 10 patients (16.1%) suffered a bleeding complication. AA-inducible platelet aggregation was significantly higher in patients with pump thrombosis ( = .01), whereas platelet aggregation in response to adenosine diphosphate (ADP) and thrombin receptor-activating peptide (TRAP) was comparable between patients without and those with pump thrombosis (both > .05). Platelet aggregation in response to AA, ADP, and TRAP was similar in patients without and with a bleeding event (all > .05). HRPR was detected in 29 patients (46.8%) and was associated with significantly higher platelet aggregation in response to AA, ADP, and TRAP as well as higher levels of soluble P-selectin compared with patients without HRPR (all  < .05). All pump thromboses occurred in patients with HRPR (3 vs 0;  = .06) and HVAD.

Conclusion: Platelet reactivity is associated with pump thrombosis in LVAD patients. HRPR may represent a risk marker for pump thrombosis, particularly in HVAD patients.