Increasing severity of functional mitral regurgitation by left bundle branch block

Heart rate‐dependent mitral regurgitation

“…LBBB‐related papillary muscle dyssynchrony has been described as a possible cause of functional mitral regurgitation even in patients with preserved ejection fraction. 6 , 7 However, as previously stated, the patient's mitral regurgitation was assessed as mild on both left ventriculography and TTE, which makes LBBB‐related dyssynchrony as the main cause of MR unlikely. Thus, it is reasonable to assume that the increase in MR severity was triggered by the prolonged left ventricular filling time and mitral annular dilation as a result of bradycardia, while the LBBB‐related dyssynchrony was probably only a contributing factor.…”

“…However, considering the patient had left bundle branch block, ventricular dyssynchrony, as opposed to atrioventricular dyssynchrony, prior to pacemaker implantation is very likely. LBBB‐related papillary muscle dyssynchrony has been described as a possible cause of functional mitral regurgitation even in patients with preserved ejection fraction 6,7 . However, as previously stated, the patient's mitral regurgitation was assessed as mild on both left ventriculography and TTE, which makes LBBB‐related dyssynchrony as the main cause of MR unlikely.…”

Recurrent acute pulmonary oedema and cardiac arrest secondary to intermittent electrical dyssynchrony: a role for cardiac resynchronization despite preserved left ventricular function

“…The association between LBBB and worsening MR is established, and CRT reduces mitral regurgitation in patients with LV systolic impairment and LBBB ,. Putative mechanisms by which LBBB induces valvular regurgitation include deformation of the mitral valve annulus,,, LV dilatation,, dyssynchronous papillary muscle activation, and regional LV dyssynchrony .…”