Cerebral Microembolization After Bioprosthetic Aortic Valve Replacement

Abstract

Background-No human physiological data exists on whether aspirin only is as effective as warfarin plus aspirin in preventing cerebral microembolization in the early postoperative period after bioprosthetic aortic valve replacement (bAVR). Methods and Results-We prospectively enrolled 56 patients who had no other indication for oral anticoagulation, who underwent bAVR and received, in an open-label fashion, either daily warfarin (for INR 2.0 -3.0) plus 81 mg of aspirin (nϭ28) or 325 mg of aspirin only (nϭ28). Cerebral microembolization was quantified at 4 hours (baseline) and at 1 month postoperatively, by recording 1-hour bilateral middle cerebral artery (MCA) microembolic signals (MES). Platelet-function analysis (PFA) of closure times (CT) on collagen was also used as a marker of platelet-dependent activation. Follow-up to 1 year was complete. Preoperative demographics and baseline platelet function were equivalent in both groups. There was no mortality, stroke, or transient ischemic attack at 1 year in either group. No significant differences were found in the proportion of patients with MES among those receiving warfarin plus aspirin versus aspirin only, at baseline (68% versus 82%, respectively; Pϭ0.4) and at 1 month (46% versus 43%; Pϭ1.0) after bAVR. The total MES and PFA were also equivalent between groups, at baseline and follow-up. Conclusions-Early after bAVR, the effects of these 2 antithrombotic regimens on cerebral microembolization and platelet function are equivalent. These data bring new mechanistic support to the premise that aspirin only may safely be used early after bAVR in patients who have no other indication for oral anticoagulation.

Apixaban Inhibits Cerebral Microembolic Signals Derived from Carotid Arterial Thrombosis in Rabbits

“…In contrast to antiplatelet agents, fewer studies (Al-Atassi et al, 2012;Demir et al, 2015) have been devoted to investigation of the effects of anticoagulants on MES, and the results are inconclusive. Since warfarin and the novel oral anticoagulants (NOACs) are the currently available options for stroke prevention in atrial fibrillation (Lin et al, 2015) and recent phase III clinical studies indicate that NOACs resulted in an overall better efficacy-safety profile than warfarin in patients with nonvalvular atrial fibrillation (Lin et al, 2015;Morais and De Caterina, 2016), we aimed to investigate the effects of apixaban as a representative example for the NOAC class on cerebral MES in our recently established preclinical model of cerebral MES.…”

Anticoagulation versus antiplatelet or no therapy in patients undergoing bioprosthetic valve implantation: a systematic review and meta-analysis

“…An interesting study evaluated the incidence of cerebral microembolisation between two groups of patients (VKA vs AP therapy) post-bioprosthetic valve implantation, at 4 hours (baseline) and at 1 month, by recording 1-hour bilateral middle cerebral artery microembolic signals as well as platelet function assays 29. Again, there was no significant difference in the rate of microembolic signals or in the platelet function assay, arguing against an added benefit of VKA over AP therapy.…”

The Role of Transcranial Doppler Monitoring in Patients with Multi‐Territory Acute Embolic Strokes: A Review

“…However, MES are more frequent when INR drops below 2 . Regarding bioprosthetic aortic valves, aspirin monotherapy exhibits a similar cerebral embolization burden, as quantified by MES counts, compared with warfarin plus aspirin …”

“…75,76 Regarding bioprosthetic aortic valves, aspirin monotherapy exhibits a similar cerebral embolization burden, as quantified by MES counts, compared with warfarin plus aspirin. 77 However, more recent studies question the association of MES with clinical outcomes and prediction of thromboembolic events. 78,79 This discrepancy may be at least partially explained by the coexistence of both gaseous and solid microemboli, with the former having no association with thromboembolic events.…”