Background: Although mitral transcatheter edge-to-edge repair (MTEER) was approved for secondary mitral regurgitation after the COAPT trial, findings of other MTEER trials have been mixed, raising questions about the applicability of COAPT results to contemporary practice.
Objectives: We used transportability methods to estimate the treatment effects of COAPT trial interventions applied to two target populations: 1) trial-eligible patients representative of U.S. clinical practice and 2) patients with secondary mitral regurgitation representative of U.S. clinical practice, regardless of trial eligibility.
Methods: We selected patients from the STS/ACC TVT Registry who were treated with MTEER for secondary mitral regurgitation from 3/14/2019 to 9/30/2023. To identify trial-eligible individuals, we applied COAPT trial eligibility criteria to the TVT Registry sample. We used inverse odds of participation weighting to standardize patient-level COAPT data to the data distribution of each target population sample and estimated treatment-specific outcomes. The primary outcome was heart failure hospitalization at two years. We examined 10 secondary outcomes including all-cause death.
Results: Our analyses included 614 COAPT trial patients and 15,275 TVT Registry patients, of which 7,289 were COAPT trial-eligible. Trial-eligible TVT Registry patients were less likely to have ischemic cardiomyopathy (34.1% vs. 60.8%) and more likely to have 4+ mitral regurgitation (79.4% vs. 47.9%) compared with trial patients. We estimated that compared with medical therapy alone, MTEER in conjunction with other COAPT interventions (e.g., optimization of medical therapy) in the trial-eligible population would result in a 2-year absolute risk reduction of 17.0% for heart failure hospitalizations (95% CI: -28.7%, -5.7%) and 15.4% for all-cause death (95% CI: -26.6%, -5.2%) - effect sizes similar to those estimated in the trial sample (p-value for difference between the trial and target population >0.05 for both). The estimated treatment effect for heart failure hospitalizations in the broader target population was also similar to that in the COAPT trial (p-value for difference = 0.90).
Conclusions: Although COAPT trial patients had different baseline characteristics than patients undergoing MTEER in contemporary U.S. practice, we estimated that treatment effects would be similar had real-world patients received COAPT trial interventions, under the assumptions required for transportability (e.g., conditional exchangeability, positivity.)
Editors
Editor-in-Chief
Harlan M. Krumholz, MD, SM, FACC
CME Editor
Ragavendra R. Baliga, MD
Author
Robert W. Yeh, MD, MSc
Important Dates
Date of Release: September 15, 2026
Term of Approval/Date of CME/MOC Expiration: September 14, 2027