麻豆传媒

Patients with secondary mitral regurgitation (MR) who were left with high gradients after a MitraClip procedure were not inherently at a disadvantage in their subsequent clinical outcomes, according to a COAPT analysis.

MitraClip-treated trial participants, divided into quartiles by mitral valve gradient (MVG) on discharge, shared similar odds of combined all-cause mortality and heart failure hospitalization at 2 years (P=0.78):

• Q1 (mean MVG 2.1 mm Hg; n=63): 43.2%
• Q2 (3.0 mm Hg; n=61): 49.2%
• Q3 (4.2 mm Hg; n=62): 40.6%
• Q4 (7.2 mm Hg; n=64): 40.9%

These findings persisted after adjustment for baseline clinical and echocardiographic characteristics, post-procedure MR grade, and number of clips implanted, reported Howard Herrmann, MD, of the Hospital of the University of Pennsylvania in Philadelphia, and colleagues in .

MVG also appeared to be unrelated to health status in terms of New York Heart Association functional class, Kansas City Cardiomyopathy Questionnaire score, or 6-minute walk time.

"Thus, although an elevated MVG should be avoided if possible, these findings suggest that the benefits of MR reduction may outweigh the effects of mild-to-moderate mitral stenosis after MitraClip treatment in select patients with HF [heart failure] and severe secondary MR," Herrmann's group concluded.

Residual MR has been considered a major determinant of outcomes after transcatheter edge-to-edge mitral valve repair (TEER). The dilemma of placing additional clips to minimize MR is that it makes mitral stenosis harder to avoid. Most guidelines recommend avoiding a post-MitraClip gradient above 5 mm Hg, Herrmann's team noted.

Caution is required when extrapolating these COAPT results to daily practice, "where a fine art of balancing further FMR [functional mitral regurgitation] reduction could be traded by worsening mitral stenosis," wrote João Cavalcante, MD, and Paul Sorajja, MD, both of the Minneapolis Heart Institute at Abbott Northwestern Hospital in Minnesota.

"Given the small number of patients with mean MVG >5 mm Hg, and even less so those with MVG ≥5 mm Hg and residual MR ≥2+ (n=10), one cannot be certain that the presence of higher gradients post-MitraClip in FMR patients are innocuous, particularly when associated with more residual MR," the duo warned in an .

The COAPT (Cardiovascular Outcomes Assessment of the MitraClip Percutaneous Therapy for Heart Failure Patients with Functional Mitral Regurgitation) trial showed that MitraClip therapy reduced the incidence of the primary outcome more than guideline-directed medical therapy alone in patients with symptomatic secondary MR.

Notably, this finding of benefit conflicted with the MITRA-FR study released around the same time. Researchers continue to search for explanations as to why the two trials came to different conclusions.

The MitraClip nevertheless won an expanded indication from the FDA to treat secondary MR in 2019. CMS started reimbursing for transcatheter mitral valve repair for secondary MR in January.

"The use of MitraClip to treat secondary MR has meant that physicians have a better way to help more of the population impacted by this kind of heart disease, specifically patients who would not be able to qualify for major surgery," Herrmann said in a Penn Medicine press release.

"It is paramount that we as researchers continue to study outcomes with new devices after they come to market so that patients can receive the greatest benefits of treatment," he continued.

Herrmann and colleagues based their analysis on the 250 MitraClip patients in COAPT who had evaluable MVGs measured at discharge.

Approximately a quarter of patients had MVG exceed 5 mm Hg at discharge. These patients were more likely women, African American, and obese.

However, the cutoff of MVG ≥5 mm Hg was not associated with a higher risk of death or mortality.

"Although this study might be underpowered to ascertain differences in outcomes between patient groups with different combinations of MVG and residual MR, we showed with different analytic approaches ... that there was no association between discharge MVG gradient and long-term outcomes in the study population," the investigators wrote.

They cautioned that their analysis does not apply to people who are not COAPT-eligible, and MVG changes with exertion were not evaluated. Moreover, the lack of intraprocedural hemodynamic data meant that the authors could not exclude the possibility that intraprocedural MVG might have affected the operator's decision to implant additional clips.

"Patient selection for TEER will continue to evolve by combining patient anatomy with intraprocedural nuances in grasping and implantation strategies, all of which come with growing operator experience," Cavalcante and Sorajja predicted.

Further evaluation of left ventricular health will also be needed, as it may be linked to post-TEER outcomes, they said.

Comment