Cardiopulmonary exercise testing as a guideline indicator for mitral valve intervention

Abstract

Abstract Background Primary mitral regurgitation (MR) is one of the most common heart valvular pathologies. However, optimum timing of surgery remains controversial. Purpose To describe changes in cardiopulmonary exercise testing (CPET) parameters after surgery for severe primary MR. Methods In a single centre prospective study, patients undergoing surgery under current ESC guidelines for severe primary MR underwent assessment with transthoracic echocardiogram, CPET, cardiac MRI and quality of life questionnaire pre-operatively and at six months after surgery. The primary outcome was a per protocol analysis of impaired post-operative functional capacity (defined as post-operative left ventricular ejection fraction on transthoracic echocardiogram <50% and/or post-operative percentage predicted peak VO2 ≤84%). Results 43 of the 50 patients recruited between February 2017 and October 2018 were included in the per protocol analysis. Thirty five patients (72.9%) had impaired post-operative functional capacity. In the overall cohort (n=43), there was a significant fall post-operatively in percentage predicted peak VO2 (ppVO2) (81.8±15.7% vs. 76.2±16.2%, p<0.01) and anaerobic threshold (AT) (48.0±11.1% vs. 44.3±10.1%, p=0.01). In patients with a class I indication for surgery (n=30), there was no significant change post-operatively in ppVO2 (79.6±15.7% vs. 75.6±16.7%, p=0.09) or AT (49.9±11.4% vs. 46.4±10.2%, p-0.09). However, in patients with a class II indication for surgery (n=13), there was a significant change post-operatively in ppVO2 (86.9±15.1% vs. 77.4±15.9%, p<0.01), but not in AT (43.5±9.6% vs. 39.5±8.3%, p=0.16). In the multivariable analysis, pre-operative left ventricular ejection fraction ≤60% (hazard ratio, 1.69; 95% confidence interval, 1.56 to 480.1, p=0.04) and pre-operative percentage predicted peak VO2 ≤84% (hazard ratio, 1.22; 95% confidence interval, 2.13 to 107.1, p<0.01) were independent predictors for impaired post-operative functional capacity. Conclusions Pre-operative percentage predicted peak VO2 ≤84% is an independent predictor of impaired post-operative functional capacity. Subject to a confirmatory study, this may help to refine current ESC guidelines for intervention for severe primary MR. Change in ppVO2 after surgery Funding Acknowledgement Type of funding source: Foundation. Main funding source(s): Rosetrees Trust and Friends of Hammersmith Hospital