Background: There are limited data comparing hemodynamic valve function in mechanical aortic valve prostheses. We compared the hemodynamic function of two commonly used mechanical aortic valve (AV) prostheses, the On-X and Top Hat valves.
Methods: Retrospective analysis of 512 patients who received AV replacement with On-X (n=252, 49%) or Top Hat (n=260, 51%) mechanical valves between 2011 and 2019. Patients were matched based on select variables. Echocardiographic data were collected pre- and postoperatively over a median follow-up of 1.39 years.
Results: A total of 320 patients were matched, 160 patients in each group. Despite being matched for left ventricular outflow tract diameter, patients in the Top Hat group received a greater prevalence of smaller tissue annulus diameter valves (≤ 21 mm) (83% versus 38%; P<0.001). Patients in the On-X group had longer aortic cross-clamp time (78 versus 64 minutes; P<0.001) during isolated aortic valve replacement. Discharge echocardiography showed no difference in the AV area index between both groups (1.00 versus 1.02 cm2/m2; P=0.377). During longer-term echocardiographic follow-up, AV area index remained stable for both valves within their respective tissue annulus diameter groups (P=0.060).
Conclusions: There was no difference between the two valves with respect to the AV area index at discharge, and hemodynamic function was stable during longer-term follow-up. The longer aortic cross-clamp time observed in the On-X group may indicate increased complexity in implantation compared to the Top Hat group.
Keywords: Aortic valve; aortic valve replacement; mechanical valve.
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