The Impact of Postoperative Thrombocytopenia in a Stentless Bioprosthetic Valve (SOLO SMART)

Background: SOLO SMART (SOLO) was introduced in Japan as a new stentless tissue valve in April 2016. Postoperative thrombocytopenia has been reported to occurs after aortic valve replacement (AVR) using SOLO. Methods: The aim of our study was to evaluate the difference in incidence and clinical impact of postoperative thrombocytopenia in patients receiving AVR between SOLO group and stented bioprosthetic valve (Stented) group. We evaluated 67 patients who underwent AVR with bioprosthetic valve for AS between April 2017 and March 2020. Severe thrombocytopenia was defined as the lowest postoperative platelet count of < 5.0×104/μl. We divided patients with AVR into SOLO and Stented groups, and compared the surgical results, prevalence of thrombocytopenia, and changes in platelet count. Results: Postoperative aortic valve area (AVA) and peak pressure gradient (P-PG) were significantly improved in the SOLO group. The lowest postoperative platelet count was significantly lower in the SOLO group. Severe thrombocytopenia was observed in 75% of the patients in the SOLO group and 7% of those in the Stented group. As a factor that causes postoperative thrombocytopenia, use of SOLO, age at surgery, and body surface area (BSA), showed significant differences (p＜0.05). Although the platelet count had the lowest value on the 2nd to 4th day after the operation, then recovered spontaneously, and at 1 month after the operation, the platelet level improved to normal values. However, in the Stented group, the platelet level recovered to the preoperative platelet level 1 week after operation, but in the SOLO group, the preoperative platelet level didn't recover even after 3 months, and as a result, it suggest that platelet recovery was prolonged in the SOLO group. Conclusion: Use of SOLO was an independent risk factor of severe thrombocytopenia after AVR. Although no clinically serious hemorrhagic complication was observed, use of SOLO may prolong postoperative platelet recovery. In consideration of the risk of thrombocytopenia, it was considered to be advantageous to select the SOLO for SAVR in cases with a narrow annulus diameter.