However, postprocedural gradient not a predictor in functional MR
Elevated postprocedural mitral valve pressure gradient (MPG) is an independent predictor of adverse clinical and functional outcomes in patients with degenerative mitral regurgitation (DMR) but not in those with functional mitral regurgitation (FMR), a new long-term outcomes study reports.
The study, published online Monday and in the May 9 issue of JACC: Cardiovascular Interventions, noted that while mitral valve transcatheter edge-to-edge repair (TEER) has become a routine treatment alternative for patients with severe mitral regurgitation (MR) at high surgical risk, the consequences of elevated MPG after TEER have been subject to “controversial debates.”
Led by Benedikt Koell, MD, from the University Heart and Vascular Center Hamburg, Germany, and the German Center for Cardiovascular Research, the team behind the study noted that while the impact of elevated MPG on outcomes in patients treated with TEER remains unclear, a recent sub-analysis of the COAPT trial showed no influence of elevated MPG on outcomes after TEER in patients with FMR.
“To the best of our knowledge, this study represents the largest analysis of postprocedural MPG and its impact on long-term outcomes after TEER,” said the authors, who noted that after adjustment for confounding risk factors, elevated MPG (≥5 mm Hg) was independently associated with inferior prognostic outcomes in patients with DMR but not in those with FMR.
“Although a definitive conclusion on functional outcomes cannot be made with the present data, at least in patients with DMR and elevated MPG, TEER did not improve functional capacity at follow-up,” they said.
Koell and colleagues investigated the adverse impact of elevated postprocedural MPG on outcome in a real-world population of 1,024 patients with severe DMR or FMR who underwent TEER at a high-volume center between September 2008 and January 2020. However, after the exclusion of patients with missing echocardiographic MPG values (n = 286) and those lost to follow-up (n = 15), a total of 713 patients were available for the present analysis.
At baseline, patients in the DMR group were, on average, older (79.9 years for DMR vs 75.4 years for FMR), while the FMR group had a higher proportion of male participants (65.1% men FMR vs 53.6% men DMR). Both the DMR (n = 265) and FMR (n = 445) groups were further split into those with low MPG (<5 mm Hg) and elevated MPG (≥5 mm Hg) after TEER (DMR: MPG <5 mm Hg [n = 167], MPG ≥5 mm Hg [n = 98]; FMR: MPG <5 mm Hg [n = 347], MPG ≥5 mm Hg [n = 98]).
Furthermore, the majority of patients were highly symptomatic at baseline, with New York Heart Association (NYHA) functional classes III and IV in 68.6% and 24.9% of patients with DMR and in 68.2% and 26.4% of those with FMR, respectively.
“Irrespective of MR etiology, patients with elevated MPG had smaller LV diameters as well as higher LVEFs compared with patients with low MPG,” said the research team, adding that in the FMR group in particular, patients with elevated postprocedural MPG had a higher rate of chronic obstructive pulmonary disease (low MPG 16.5% vs elevated MPG 27.8%; P = 0.018) and lower N-terminal pro–B-type natriuretic peptide levels (4,927 pg/mL [interquartile range (IQR): 2,303-8,675 pg/mL] vs 3,231 pg/mL [IQR: 1,683-6,848 pg/mL]; P = 0.031) than those with low MPG.
Functional outcomes were measured by NYHA functional class at baseline and follow-up, while exercise capacity was assessed by 6-minute walk distance (6MWD) at baseline and follow-up.
The primary study endpoint was defined as a combined endpoint of all-cause mortality and heart failure rehospitalization after 5-year follow-up. Three secondary endpoints were defined: all-cause mortality, heart failure rehospitalization, and the composite endpoint of all-cause mortality, heart transplantation, left ventricular (LV) assist device implantation, surgical mitral valve repair or replacement, and/or redo TEER.
Analysis showed that elevated postprocedural MPG was present in 37.0% of those with DMR and (n = 98) and 22.0% of those with FMR (n = 98).
For patients with DMR and low MPG, a significant improvement in 6MWD at 12 months (n = 95, delta [D] 60 m [IQR: 10 to 90 m]; P = 0.045) and 24 months (n = 47, D 60 m [IQR: -15 to 139 m]; P = 0.036) was observed.
The team noted that Kaplan-Meier analyses did not demonstrate significant differences for the primary endpoint in patients with DMR (low vs elevated MPG, 67.3% vs 74.4%; P = 0.06) and those with FMR (78.6% vs 74.8%; P = 0.54).
Cox regression analysis for all endpoints was then performed, stratified for both MR etiologies, to assess the prognostic impact of elevated postprocedural MPG. After full adjustment, elevated postprocedural MPG was fund to be an independent predictor of the primary endpoint DMR (hazard ratio [HR]: 1.59; 95% confidence interval [CI]: 1.03-2.45; P = 0.034) and all secondary endpoints in patients with DMR.
In contrast, elevated postprocedural MPG was not associated with the occurrence of the primary endpoint (HR: 0.87; 95% CI: 0.63-1.22; P ¼ 0.43) or the secondary endpoints in patients with FMR.
“In the present study, we demonstrated that after adjustment for confounding clinical, echocardiographic, and procedural risk factors, including rMR [residual mitral regurgitation] ≥2+ and baseline MPG, elevated postprocedural MPG (≥5 mm Hg) was independently associated with the occurrence of the primary and secondary endpoints in patients with DMR but not in those with FMR,” said Koell and colleagues.
They added that the “potentially incompatible” interests of on one hand achieving the lowest possible rMR while preventing iatrogenic mitral stenosis on the other “represent an omnipresent conundrum of any TEER procedure.”
“Whether one outweighs the other is currently unclear and needs to be investigated in future prospective trials,” they said.
Koell R, Ludwig S, Weimann J, et al. Long-Term Outcomes of Patients With Elevated Mitral Valve Pressure Gradient After Mitral Valve Edge-to-Edge Repair. JACC Cardiovasc Interv 2022;15:922-934.
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