Aortic valve calcification of surgical bioprostheses and its impact on clinical outcome

Introduction

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.

Method

Between 2011 and 2019, AVC was assessed in 361 patients with surgical BP on in vivo computed tomography (CT) scanner (6.4 ± 4.3 years after surgery). Follow-up was obtained in all patients. Ex vivo CT-scans were performed in 37 explanted BP.

Results

After exclusion of 19 (5.2%) CT-scans, mean in vivo AVC was 307 ± 500 AU in the remaining 342 BP (77 ± 9 years, 64% male). Of these, 183 (53.5%) had a structural valve degeneration (SVD) with an AVC of 562 ± 570 AU compared with 13 ± 43 AU (P < 0.0001) for non-SVD BP. Early calcification was observed in around 10% of BP (12/124) examined before the 3rd postoperative year. In explanted BP in vivo AVC correlated strongly with ex vivo AVC (r = 0.88, P < 0.0001). An in vivo AVC > 100 AU (n = 147, 43%) had an excellent specificity (96%) for diagnosing stage 2–3 SVD. Patients with AVC > 100 AU had worse survival compared with those with an AVC < 100 (n = 195, 57%). In multivariable analyses, AVC value was a predictor of overall mortality (HR = 1.16 [1.04–1.29]; P = 0.009), cardiovascular mortality (HR = 1.21 [1.03–1.41]; P = 0.021) and cardiovascular events (HR = 1.19 [1.08–1.31]; P = 0.001). After further adjustment for SVD diagnosis, AVC remained a predictor of overall mortality (HR = 1.24 [1.07–1.44]; P = 0.005), and cardiovascular events (HR = 1.16 [1.02–1.32]; P = 0.029).

Conclusion

CT-scan AVC of surgical BP is a reliable tool for assessing leaflets calcification. Whereas calcification can develop early after surgery, an AVC > 100 AU is tightly associated with SVD, and is a strong predictor of overall mortality and cardiovascular events, even after adjustment for SVD diagnosis. Hence, AVC scoring is a complementary tool to echocardiography that should be used in the follow-up of patients with surgical aortic BP.