Transmitral Gradients and Mortality Following Transseptal Transcatheter Mitral Valve in Valve

Area of Science:

• Cardiovascular Medicine
• Interventional Cardiology
• Cardiac Surgery

Background:

• Transcatheter mitral valve in valve (MVIV) procedures are increasingly common.
• Echocardiographic transvalvular mitral gradients (TMGs) are used to assess outcomes after MVIV.
• Limited data exists on the association between TMGs and clinical outcomes post-MVIV.

Purpose of the Study:

• To investigate the relationship between discharge and 30-day TMGs and mortality following MVIV.
• To evaluate the association between TMGs and other clinical outcomes post-MVIV.

Main Methods:

• Utilized data from the Society of Thoracic Surgeons/American College of Cardiology TVT Registry (August 2015-March 2024).
• Employed Cox proportional hazards regression models with cubic spline functions to analyze TMGs and all-cause mortality.
• Categorized TMGs into low (<4 mm Hg), intermediate (4-7 mm Hg), and high (>7 mm Hg).
• Generated Kaplan-Meier estimates for mortality and composite endpoints, comparing TMG ranges at discharge and 30 days.

Main Results:

• Included 5,401 MVIV patients with a median follow-up of 377 days.
• Low TMG (<4 mm Hg) was associated with lower cardiac output and cardiac index compared to intermediate and high TMGs.
• Low discharge TMG correlated with increased 3-year all-cause mortality hazard (aHR: 1.52) versus intermediate TMG and (aHR: 1.35) versus high TMG.
• Discharge and 30-day TMG measurements showed variability and should not be used interchangeably.

Conclusions:

• TMG <4 mm Hg post-MVIV is linked to reduced cardiac output and increased 3-year mortality.
• Significant changes in TMG occur between discharge and 30 days post-MVIV.
• Discharge TMG alone is insufficient to determine procedural success or valve performance; cardiac output must be considered.