OUTCOMES OF STENTLESS BIOPROSTHETIC AORTIC VALVES: THE ALBERTA EXPERIENCE

Abstract

Stentless aortic bioprostheses have demonstrated hemodynamic benefits including laminar flow and larger effective orifice area. However, data on the long-term performance of this valve design is limited relative to conventional stented bioprostheses. As well, many stentless valves were implanted via full-root replacement, potentially making reoperation more technically demanding and higher risk. Alberta’s two cardiac centres have one of the largest experiences with stentless valves in North America. The objective of this study was to compare stentless and stented bioprostheses to assess long-term outcomes, including results of reoperative surgery. Two large prospectively maintained databases, including the province-wide APPROACH database, were used to create a retrospective consecutive cohort. Patients undergoing bioprosthetic aortic valve replacement (AVR) from January 2002 to March 2014 were included. All operations were performed at the Foothills Medical Centre (Calgary) or the University of Alberta Hospital (Edmonton). Patient characteristics, surgical details and clinical outcomes were compared between stentless and stented valve cohorts. During the timeframe, 3959 Albertans underwent AVR with either stentless (n=1238) or stented (n=2721) bioprotheses. The 2 cohorts were similar overall, though patients in the stentless group were younger (67.0±12.5 vs. 70.8 years; p<0.0001), and had higher incidence of COPD and dyslipidemia. The majority of stentless valves were Medtronic Freestyle porcine prostheses (n=992; 80.1%). Over the 12-year period, there was no difference in survival between the groups. Table 1 outlines reoperative outcomes. During a mean follow-up of 7.9±2.6 vs 5.3±2.4 years (stentless vs stented), there was a similar rate of AVR-related reoperation in both groups (4.3% vs. 8.6%, stentless vs. stented; p=0.32). Both reoperative cohorts demonstrated similar crossclamp times and cardiopulmonary bypass times. There was no difference in perioperative mortality at reoperation (7.6 vs 6.4%, stentless vs. stented; p=0.22). Reoperation in both groups were due to multiple reasons, but most common was structural valve deterioration (Figure 1). This study presents the largest reported cohort of sutureless valve patients. Outcomes suggest no significant difference in survival or rate or reoperation between stented and stentless valves over a 12-year follow-up period. Furthermore, reoperation in patients with stentless valves, though thought to be accompanied with higher technical difficulty and risk, does not demonstrate increases in crossclamp times, cardiopulmonary bypass times, perioperative mortality or all cause mortality. In the future, we hope to both extend the study period to determine differences in incidence of structural valve deterioration together with mechanism of failure.View Large Image Figure ViewerDownload Hi-res image Download (PPT)