Calcification of surgical aortic bioprostheses and its impact on clinical outcome

Abstract

Aims: Aortic valve calcification (AVC) of surgical valve bioprostheses (BP) has been poorly explored. We aimed to evaluate in-vivo and ex-vivo BP AVC and its prognosis value.

Methods and results: Between 2011 and 2019, AVC was assessed using in-vivo computed tomography (CT) in 361 patients who had undergone surgical valve replacement 6.4±4.3 years earlier. Ex-vivo CT scans were performed for 37 explanted BP. The in-vivo CT scans were interpretable for 342 patients (19 patients [5.2%], were excluded). These patients were 77.2±9.1 years old and 64.3% were male. Mean in-vivo AVC was 307±500 Agatston unit (AU). The AVC was 562±570 AU for the 183 (53.5%) patients with structural valve degeneration (SVD) and 13±43 AU for those without SVD (p<0.0001). In-vivo and ex-vivo AVC were strongly correlated (r=0.88, p<0.0001). An in-vivo AVC>100 AU (n=147, 43%) had a specificity of 96% for diagnosing Stage 2-3 SVD (area under the curve=0.92). Patients with AVC>100 AU had a worse outcome compared with those with AVC≤100 AU (n=195). In multivariable analysis, AVC was a predictor of overall mortality (hazard ratio [HR] and 95% confidence interval=1.16[1.04-1.29]; p=0.006), cardiovascular mortality (HR=1.22[1.04-1.43]; p=0.013), cardiovascular events (HR=1.28 [1.16-1.41]; p<0.0001), and re-intervention (HR=1.15 [1.06-1.25]; p<0.0001). After adjustment for Stage 2-3 SVD diagnosis, AVC remained a predictor of overall mortality (HR=1.20 [1.04-1.39]; p=0.015) and cardiovascular events (HR=1.25 [1.09-1.43]; p=0.001).

Conclusion: CT scan is a reliable tool to assess BP leaflet calcification. An AVC>100 AU is tightly associated with SVD and it is a strong predictor of overall mortality and cardiovascular events.

Keywords: aortic valve calcification; computed tomography; echocardiography; structural valve degeneration; surgical aortic valve bioprostheses.