Impact of Mitral Valve Prosthesis on Stroke after Insertion of Veno-Arterial Membrane Oxygenation for Postcardiotomy Shock

Abstract

Purpose Veno-arterial membrane oxygenation (VA-ECMO) is used in profound postcardiotomy shock (PCS). Previous study raised the possibility that use of VA-ECMO after mitral valve replacement (MVR) may pose a risk of valve thrombosis and embolism including stroke likely due to low transvalvular flow. This study focused on stroke after valve surgery requiring VA-ECMO. Methods Of 482 adult patients undergoing VA-ECMO from January 2011 to July 2020, 113 received VA-ECMO for PCS: coronary artery bypass Grafting (CABG): N=44; Mitral valve repair: N=12; Aortic valve replacement (AVR), N=28; MVR, N=29. Precautions taken to limit thromboembolism included: (1) low VA-ECMO flows were maintained between 1.5-2.2 L /min/m2, if possible, to provide hemodynamic support while maximizing trans-valvular flow and prosthesis washing; (2) anticoagulation was initiated within 24 hours postoperatively; (3) A bioprosthesis was used for 98.2% of valve replacements. The incidence of stroke and survival to discharge were primary outcomes. Results Peripheral VA-ECMO cannulation was performed in 87.6% (CABG, 79.5%; MV repair, 100%; AVR, 96.4%; and MVR 86.2%, p=0.483). Of these, 65.7% of peripheral cannulation was axillary VA-ECMO. The overall survival for PCS was 57.5%, with an incidence of stroke of 11.5% (CABG, 6.8%; MV repair, 8.3%; AVR, 10.7%; and MVR 20.7%; CABG or MV repair vs MVR, p=0.066; CABG or MV repair vs. AVR, p=0.889). Median support length of VA-ECMO was 6 days. In 6 patients who had stroke after MVR, 5 patients (83.3%) developed stroke after decannulation with a median interval of 1 day. The incidence of postoperative atrial fibrillation was 15.9%, 25%, 28.6%, and 32.1%, respectively (P=0.405). In univariable logistic regression analysis, MVR was a predisposing factor for postoperative stroke (odds ratio: OR, 3.39: p=0.078), but AVR (OR, 1.56: p=0.579) and central cannulation (OR, 3.03: p=0.178) were not. Conclusion The incidence of stroke after MVR was significant in PCS requiring VA-ECMO which suggests that an intracardiac embolic source may cause stroke with recovery of heart function. An alternative mechanical support or treatment strategy may be considered after MVR given the high rate of stroke during VA-ECMO support.