Effects of cardiac resynchronization therapy on the mechanisms underlying functional mitral regurgitation in congestive heart failure

Aims: Functional mitral regurgitation (FMR) improvement induced by cardiac resynchronization therapy (CRT) has been related to left ventricular (LV) remodeling reversal and contractility enhancement. The effects induced by the changes of LV synchronicity indexes on FMR severity have not been investigated. Methods and results: In 30 patients with CRT for heart failure (HF) and QRSO130 ms, LV function parameters, FMR severity as mitral jet regurgitation/ left atrial area ratio (JA/LAA) and standard deviation (SD) of the time to the systolic peak velocity at 6-basal and mid-LV segments as asynchrony indexes were evaluated (echo/tissue Doppler) before and 6 months after implant. At followup, 15 patients resulted responders to LV reverse remodeling with R15% endsystolic volume (ESV) and LV systolic function improvement. Improvement of FMR with R15% JA/LAA reduction was observed in 19 patients, 7 were nonresponders to LV reverse remodeling. In patients with R15% JA/LAA reduction a significant decrease of LV asynchrony indexes was observed as compared to patients without R15% JA/LAA reduction in whom LV asynchrony indexes were increased. Reduction of LV mid-segmental asynchrony was the variable most strongly related to JA/LAA reduction (r2Z0.697, P!0.01), with good agreement between observed and predicted values (only 1 patient outside the meanG2SD).