Impact of procedural success definitions on long-term outcomes in patients with rheumatic mitral stenosis treated with percutaneous mitral valvuloplasty
Authors: Manoret P , Chichareon P , Nilmoje T , Thungthienthong M , Songsangjinda T , Chamnanphol N , Suwanugsorn S , Jintapakorn W 
Published: November 2023

Abstract

Background
Three different definitions of PBMV success have been reported in the literature. It is uncertain which definitions should be used in practice or clinical studies since there have been no comparative studies on the impact of these definitions on long-term outcomes after PBMV.

Purpose
We assessed the impact of the three PBMV success definitions on long-term outcomes in rheumatic MS patients treated with PBMV.

Methods
This was a retrospective study on consecutive severe rheumatic MS patients treated with PBMV in tertiary-care university hospital center between January 2003 and October 2020. Patients with in-hospital complications (death, emergency surgery or stroke) were excluded. Definition A was post-PBMV mitral valve area (MVA) ≥ 1.5 cm2 or ≥ 50% increase in MVA and mitral regurgitation less than 3+. Definition B was MVA ≥ 1.5 cm2 and MR ≤ 2+, and definition C was ≥ 50% increase in MVA or area of ≥ 1.5 cm2, with no more than 1 grade increment in MR severity. The patients were grouped according to success or no success according to each success definition. Cox regression analyses were performed to assess the associations between PBMV success and the composite outcome of all-cause death, mitral surgery or re-PBMV at long-term. Net reclassification improvement (NRI) was used to compare the impact of the success definitions.

Results
Of 589 patients included in the study, 83.2% were women with a mean age of 41.6 years and median Wilkin score of 8. The mean follow-up time was 5.5 years. The PBMV success rates according to the A, B and C definitions were 81.15%, 60.27% and 74.87%, respectively.
Patients with PBMV success according to the A or B definitions had significantly lower risk of the composite outcome than those without success (success vs no success, definition A – HR 0.64, [95% CI 0.46-0.87], p 0.005, definition B – HR 0.71, [95% CI 0.53-0.94], p 0.016). Patients with PBMV success according to definition C had a similar risk of the composite outcome as those without success (HR 0.78, [95% CI 0.57-1.05], p 0.10). Patients with PBMV success according to definition A had a significantly lower risk of all-cause death than their counterparts (adjusted HR 0.57, [95% CI 0.38 - 0.86], p 0.006). The risk of death in patients with PBMV success according to the B or C definitions were similar to those without success. The c-indexes and 95% CIs for the composite outcomes of definitions A, B and C were 0.56 [0.52-0.60], 0.57 [0.52-0.61], and 0.54 [0.50-0.58], respectively. The A definitions discriminated the composite outcome better than the C definition (NRI – A vs. C 38.07%, [95% CI 13.18%-84.86%). The discriminative ability of the B definition was similar to the C definition (NRI - B vs. C 24.38%,[95% CI 11.37%-78.87%]).

Conclusions
The PBMV success rate varied among the different success definitions. The impact of success definitions A and B on long-term outcomes seemed to be better than the C definition.Characteristics of study patientsKaplan-Meier cumulative event