Low forward stroke volume index after transcatheter edge-to-edge repair for secondary mitral regurgitation predicts a worse prognosis in a 2-year follow-up
Authors: Smarz K , Dulgheru R , Tysarowski M , Lancellotti P 
Published: January 2025

Abstract

Background
Transcatheter edge-to-edge repair (TEER) is an established treatment for patients with heart failure (HF) and significant secondary mitral regurgitation (SMR). While TEER often reduces mitral regurgitation (MR) severity, alleviating symptoms and improving prognosis, some patients do not experience these benefits. The absence of improvement in forward stroke volume may underlie this lack of response.

Aim
To evaluate the prognostic significance of forward stroke volume index (FSVi) following TEER for SMR.

Methods
We retrospectively analysed data from consecutive patients referred for TEER in our academic hospital from October 2016 to June 2023. The inclusion criteria were: symptomatic moderate to severe and severe SMR, anatomical suitability for TEER, and optimal medical therapy. Transthoracic echocardiograms (TTE) were performed before (up to 3 months pre-TEER, TTE-0), within 48 hours (TTE-1), and 6 months post-procedure (TTE-2). The FSVi was calculated by multiplying the left ventricular outflow tract area by the left ventricular outflow tract velocity-time integral. Patients were followed for a mean of 2 years. The composite endpoint was all-cause mortality or hospitalisation due to HF.

Results
Out of 67 patients treated with TEER, we included 50 patients who had follow-up at our hospital, TEE-0, and at least one of TEE-1 or TEE-2. Six patients with primary MR were excluded. Thus, 44 patients (mean age 69.7±8.2 years, 77% male) were included in the study. These patients were in NYHA class II to IV, with a median EuroSCORE II of 13% (IQR 7, 23), and a median LVEF of 31% (IQR 26, 36), 77% had ischaemic cardiomyopathy. The mean follow-up was 1.6±0.7 years. No patients were lost to follow-up. There were 22 composite endpoints including 12 deaths. At baseline patients in the group with composite endpoint were most often diabetic, had higher NYHA class, and lower 6-minute walking test distance. Echocardiographic parameters were similar in both groups. Median FSVi in TTE – 0 was 29 mL/m2 (22, 34) vs 31 mL/m2 (25, 36), p=0.2 (in the group with and without composite endpoint). After TEER, FSVi was significantly lower in the group with versus without a composite endpoint in TTE -1 [32 mL/m2 (27, 34) vs 38 mL/m2 (33, 43), p=0.005] and TTE -2 [32 mL/m2 (22, 33) vs 40 mL/m2 (34, 48), p=0.001]. The group with composite endpoint had higher NYHA class, lower 6-minute walking test distance, lower LVEF, and higher resting heart rate 6 months after TEER.
The optimal cut-off value for the FSVi in TTE – 1 after TEER for predicting the composite endpoint was 35 ml/m2 (AUC 0.76, 80% sensitivity, 70% specificity, PPV 0.73, NPV 0.78). A significant difference in the composite endpoint occurrence was observed between groups with FSVi &gt; 35 ml/m2 and ≤ 35 ml/m2 (TTE – 1) during the follow-up (Figure).

Conclusions
FSVi in early postprocedural TTE predicts death or rehospitalisation for HF in patients treated with TEER for SMR.
Kaplan-Meier curves