Mixed findings from mitral transcatheter edge-to-edge repair (MTEER) trials have raised uncertainty about how well the COAPT trial results apply to contemporary clinical practice. A transportability analysis published in the Journal of the American College of Cardiology evaluated whether treatment effects observed in COAPT would remain consistent in real-world U.S. populations with secondary mitral regurgitation. 

The analysis combined patient-level data from the COAPT trial with data from the Society of Thoracic Surgeons/American College of Cardiology Transcatheter Valve Therapy (TVT) Registry using inverse odds of participation weighting.The study included 614 COAPT participants and 15,275 registry patients treated with MTEER between 2019 and 2023, including 7,289 patients who met COAPT eligibility criteria. 

Findings

• Compared with COAPT participants, trial-eligible registry patients were less likely to have ischemic cardiomyopathy (34.1% vs 60.8%) and more likely to have severe (4+) mitral regurgitation (79.4% vs 47.9%).
• In the trial-eligible target population, MTEER combined with other COAPT interventions was associated with an estimated 2-year absolute risk reduction of 17.0% for heart failure hospitalization compared with medical therapy alone (95% CI, −28.7% to −5.7%).
• The estimated 2-year absolute risk reduction for all-cause mortality was 15.4% (95% CI, −26.6% to −5.2%).
• Estimated treatment effects for heart failure hospitalization were similar to those observed in COAPT (P for difference >0.05).
• Comparable findings were also observed in the broader treatment-candidate population representative of U.S. clinical practice (P=0.90). 

The findings suggest that COAPT-like MTEER strategies may provide similar reductions in heart failure hospitalization and mortality in contemporary U.S. practice populations, despite differences in baseline characteristics between trial participants and real-world patients.