Transmitral Gradients and Mortality Following Transseptal Transcatheter Mitral Valve in Valve.

BACKGROUND

Echocardiographic transvalvular mitral gradients (TMGs) following transcatheter mitral valve in valve (MVIV) are regarded as correlates of clinical outcomes despite limited data.

OBJECTIVES

The aim of this study was to examine the association between discharge and 30-day TMGs and mortality, as well as other clinical outcomes, following MVIV.

METHODS

The Society of Thoracic Surgeons/American College of Cardiology TVT (Transcatheter Valve Therapy) Registry was used to extract data for all comers undergoing MVIV from August 2015 to March 2024. Adjusted and unadjusted Cox proportional hazards regression models with cubic spline functions were used to explore the relationship between discharge TMG post-MVIV and all-cause mortality. TMG ranges included low (<4 mm Hg), intermediate (4-7 mm Hg), and high (>7 mm Hg). Kaplan-Meier estimates were generated for all-cause mortality and the composite endpoint of all-cause mortality or stroke across TMG ranges (at discharge and at 30 days), with overall curve comparisons performed using log-rank tests. Pairwise comparisons were based on adjusted HRs and corresponding P values from Cox proportional hazards models.

RESULTS

The study included 5,401 MVIV patients, with a median follow-up duration of 377 days (Q1-Q3: 58-687 days). Compared with intermediate and high TMG, low TMG had lower invasive cardiac output (CO) (P = 0.0003 and P < 0.0001, respectively) and cardiac index (P = 0.04 and P = 0.0002, respectively). Low discharge TMG was associated with an increased 3-year all-cause mortality hazard compared with intermediate discharge TMG (adjusted HR: 1.52; 95% CI: 1.22-1.89; P = 0.0002) and compared with high discharge TMG (adjusted HR: 1.35; 95% CI: 1.07-1.71; P = 0.01; 896 mortality events for the entire cohort). Discharge and 30-day gradient groups varied and should not be interchangeable.

CONCLUSIONS

Following MVIV, TMG <4 mm Hg was associated with lower CO and cardiac index and increased mortality at 3 years compared with TMG 4 to 7 mm Hg and >7 mm Hg. TMG changed significantly from discharge to 30 days. Discharge TMG should not be the sole determination of procedural outcome, valve performance, or the need for optimization following MVIV without incorporating CO.