Severe functional mitral regurgitation manifested by isometric handgrip: revival of simple and non-invasive stress test in the era of transcatheter mitral valve repair

Abstract

Isometric handgrip is a simple and non-invasive stress test, and has been used prior to open-heart surgeries. The utility of handgrip in transcatheter mitral valve repair (TMVR) remains undetermined. A 78-year-old-female with previous anteroseptal myocardial infarction had lateral myocardial infarction 3 months before TMVR, and developed several acute pulmonary edemas thereafter. Echocardiography depicted reduced ejection function of 39%, and moderate functional mitral regurgitation (FMR) due to tethering [effective regurgitation orifice area (EROA): 0.23 cm2]. She had taken a betablocker and diuretics, but not angiotensin-converting enzyme inhibitor due to occasional low blood pressure, from second myocardial infarction, and there was no residual coronary stenosis necessitating additional revascularization. To assess the indication of intervention to FMR, we stressed her left ventricle using isometric handgrip (Fig. 1a). After she grasped at 50% of her maximum strength (7.5 kg) for three minutes, her blood pressure and heart rate were elevated from 120/64 mmHg and 46 beats/min to 151/99 mmHg and 75 beats/min. Moderate FMR deteriorated to severe grade (EROA: 0.42 cm2), and her estimated systolic pulmonary pressure rose from 23 to 62 mmHg (Fig. 1b, c). We posited that the intervention to FMR was efficacious to prevent next pulmonary edema. Considering a high surgical risk (Society of Thoracic Surgeons score for mitral valve replacement: 10.88%), we underwent TMVR using MitraClip NT system (Abbott, Menlo Park, CA, USA). After deployment of two clips at the middle and lateral A2-P2 leaflet, which were corresponded to regurgitation orifice, FMR regressed to trivial grade (Fig. 1d). 2 months following TMVR, FMR had not deteriorated on isometric handgrip (Fig. 1e, f). The patient had no recurrence of pulmonary edema for 6 months after TMVR. TMVR is indicated for patients with severe mitral regurgitation, however, the severity of FMR could dynamically change under several cardiac conditions [1, 2]. In Japan, TMVR was acknowledged to dynamic FMR, which was aggravated from moderate grade or less to severe grade at stress. Cycle exercise is a common stress test, whereas there are concerns regarding resource utilization and motion artifacts. Most TMVR candidates are elderly and/or have refractory heart failure, and may not obtain sufficient load on cycle exercise. Isometric handgrip is feasible to perform among debilitated patients, and we can visualize the change of regurgitation toward elevated afterload and oxygen demand [3]. Among patients whose TMVR indications are inconclusive, isometric handgrip test can be helpful for therapeutic decision making.