Early postoperative prognostic markers of bioprosthetic mitral valve dysfunction in patients aged ≤ 70 years: a retrospective cohort study

Abstract Background Although guidelines recommend bioprosthetic mitral valve replacement (MVRb) for patients aged 70 and older, an increasing number of younger patients (≤ 70 years) are undergoing MVRb due to specific clinical indications. This study aims to identify early postoperative prognostic markers associated with subsequent bioprosthetic mitral valve dysfunction (MVD) in patients ≤ 70 years who underwent MVRb. Methods This retrospective study included 238 patients aged ≤ 70 years who underwent MVRb between January 2009 and December 2022. MVD was defined by new or progressive prosthetic morphological abnormalities with haemodynamic deterioration from the 1–3-month postoperative reference examination. LASSO-selected variables were entered into a multivariable cause-specific Cox model and incorporated into a nomogram. Internal validation used 1,000 selection-aware bootstrap resamples, and nomogram-based risk groups were compared using competing-risk analysis. Results During a median echocardiographic follow-up of 166.2 months (IQR, 77.8–175.5 months), MVD occurred in 64 of 238 patients. NYHA functional class ≥ III (HR, 1.89; 95% CI, 1.13–3.17), PASP per 10 mmHg (HR, 1.93; 95% CI, 1.44–2.59), mean transmitral gradient per 1 mmHg (HR, 1.31; 95% CI, 1.16–1.49), and EOA per 0.5 cm² (HR, 0.51; 95% CI, 0.38–0.68) were independently associated with MVD (all P ≤ 0.05). Results were consistent in sensitivity analyses. The nomogram showed good internal discrimination, with an optimism-corrected C-index of 0.791 (95% CI, 0.740–0.840), with corrected AUCs of 0.842 and 0.809 at 7 and 10 years, respectively. Risk groups showed significantly different cumulative incidences of MVD (Gray’s P < 0.001). Conclusions Key prognostic markers for MVD in younger patients who underwent MVRb include advanced NYHA class, elevated PASP, higher MG and reduced EOA. The nomogram may aid postoperative risk stratification, but external validation is required before clinical application.