Intrinsic myocardial dysfunction:
The volume overload of chronic MR results in progressive eccentric LV hypertrophy and an eventual decline in contractile performance. RV dysfunction in patients with chronic MR is often overlooked but occurs as a consequence of left-sided heart disease. RV dysfunction has previously been shown to occur in approximately 30% of patients referred for MV repair surgery [1-3], and is found in up to 50% of patients with severe MR and LV dysfunction [1-3]. More than three-quarters of patients enrolled in our study had significant RV dysfunction pre-operatively (RVFAC <35% and RVFWLS ≤20%), and of the patients who had detectable TR, all had a PASP ≥25mmHg by echocardiography. The prevalence of pre-operative RV dysfunction has been poorly described in transcatheter treated patients to date [19, 20], and is significantly higher in our population than in a previous surgical MV repair series [3]. This finding is unsurprising given that our cohort was deemed too high-risk for conventional mitral valve surgery, but nevertheless highlights the need to monitor for early or late RV dysfunction and/or failure as a consequence of abrupt LV unloading after Tendyne TMVI.