Post Transcatheter Aortic Valve Replacement Platelets Activity (the TPA Study)

Background: Post transcatheter aortic valve replacement (TAVR) thrombotic complications are a major problem jeopardizing the valve function. Patients who had a valve thrombosis suffer from poor outcome and accelerated valve degeneration, despite medical treatment. Recently it was shown in a prospective study that routine use of anticoagulation was associated with worse outcome, thus anti-platelet agents remained the major anti-thrombotic therapy post TAVR. We aimed to investigate platelet reactivity andprevalence and predictors of poor platelets response to dual antiplatelet therapy (DAPT) among TAVR patients.

Methods: We investigated 55 patients undergoing TAVR in a tertiary center. All patients were given aspirin and clopidogrel loading doses 12 hours pre-TAVR. Platelet reactivity was prospectively evaluated using conventional aggregometry (in response to adenosine diphosphate [ADP] and archidonid-acid [AA]) within 24 hours of TAVR. Patients with AA-induced platelet aggregation > 20% and ADP-induced platelet aggregation > 50% were designated as poor responders.

Results: Mean age of the study population was 80±6, of whom 45% were women. Median AA and ADP were 18(IQR 12-25) and 45 (IQR 34-61), respectively. 20 patients (36%) had AA-induced PA > 20% and 24 (43%) had ADP-induced PA > 50%. Thirteen patients (24%) were defined as poor responders. Poor responders were more likely to have chronic renal failure (19% vs. 46%, p=0.05), baseline right bundle branch block (4.8% vs. 31%, p=0.021) and to have higher baseline HbA1c (6% vs. 7.4%, p=0.03). Interestingly, higher use of balloon pre-dilatation was associated with poor platelet response to DAPT (OR=5.7, CI 1.45-22.5, p<0.012). Poor responders to Aspirin as measured by AA-induced platelet aggregation were more likely to have post TAVR heart failure (38% vs. 0%, p=0.02).

Conclusion: Despite the routine use of DAPT up to one-quarter of TAVR patients disclose poor anti-platelet response. This phenomenon was associated with patient`s characteristics (chronic renal failure and higher Hb A1C) but also with severity of AS and balloon pre-dilatation. Exploring outcome among TAVR patients with respect to platelets function may help shed a light on the prognostic effect of post TAVR platelet reactivity.