Prevalence, mechanisms and prognostic impact of dynamic mitral regurgitation unmasked by handgrip exercise in patients with hypokinetic non-dilated and dilated cardiomyopathy

Abstract Background Recent studies suggest that mitral regurgitation (MR) is a dynamic condition influenced by global and regional left ventricular (LV) remodeling as well as mitral valvular deformation. Exercise testing plays a substantial role in assessing the hemodynamic relevance of MR and is recommended by current guidelines. Handgrip exercise may serve as alternative exercise intervention to bicycle exercise, as it is easy to perform even bedside. However, there are no data yet, on the prevalence, mechanisms and prognostic impact of dynamic MR in patients with dilated cardiomyopathy using isometric exercise testing. Aims We aimed to assess the prevalence, hemodynamic consequences, and prognostic impact of exercise-induced changes in MR in patients with hypokinetic non-dilated and dilated cardiomyopathy. Methods Patients with hypokinetic non-dilated and dilated cardiomyopathy and at least mild MR who underwent handgrip echocardiography at the University Hospital Duesseldorf between January 2018 and September 2021 were enrolled.Patients were followed-up for one year to assess clinical outcomes. We assessed all-cause mortality, HF-associated hospitalizations, MV surgery, transcatheter edge-to-edge repair (TEER), left ventricular assist device implantation and heart transplantation during follow-up. Results Fifty-eight patients were included (mean age 70±15 years; 41% female; mean LVEF 37±10%). At rest, 28 patients (48%) presented with mild MR, and 30 patients (52%) had moderate MR. Fifteen patients (26%) with non-severe MR at rest, developed dynamic severe MR during handgrip exercise. Patients with dynamic severe MR had advanced MR at rest, larger left atrial dimensions, and increased mitral annulus diameter (all p<0.01). During exercise, LVEDVi, LVESVi and parameters of local left ventricular remodeling (tenting height, tenting area) were increased in patients with dynamic severe MR compared to those with non-severe MR (all p<0.05). During one-year follow-up, there was no difference regarding all-cause mortality and HF hospitalizations in patients with dynamic severe MR and non-severe MR (Log-rank test Chi2 0.262; p=0.609)(Figure 1). However, patients with dynamic severe MR more often underwent mitral valve surgery/intervention than patients with non-severe MR (Log-rank test Chi2 29.41; p<0.001)(Figure 1). Conclusion Our results demonstrate that the evaluation of non-ischemic MR only at rest underestimates the full severity of the lesion. Handgrip exercise unmasks severe MR in every fourth patient with non-severe MR at rest. These data may have implications for therapeutic decision-making in symptomatic patients with hypokinetic non-dilated and dilated cardiomyopathy and non-severe MR at rest. TEER might present an effective treatment option to improve clinical outcomes in patients with non-ischemic cardiomyopathy and non-severe MR at rest but dynamic severe MR during exercise.Figure 1