Key result
Cardiac resynchronization therapy acutely reduces functional mitral regurgitation by increasing closing forces and improving coordinated timing of mechanical activation of papillary muscles.
Why the study?
Does cardiac resynchronization therapy reduce dynamic mitral regurgitation in heart failure patients with intraventricular conduction delay?
Does cardiac resynchronization therapy reduce dynamic mitral regurgitation in heart failure patients with intraventricular conduction delay?
CRT reduces functional mitral regurgitation by increasing closing forces and coordinating papillary muscle activation, an effect that is immediately lost if pacing is withheld.
Cardiac resynchronization therapy (CRT) improves clinical status, quality of life, and exercise capacity, promotes reverse left ventricular (LV) remodelling, and prolongs survival of selected heart failure patients with intraventricular conduction delay.1,2 However, 30% of patients do not respond to CRT. Response to CRT largely depends on the extent of LV dyssynchrony, but also on the severity of functional mitral regurgitation (MR). Responders are characterized by a decrease in LV dyssynchrony—restoration of a more normal ventricular activation pattern—and in MR degree. Functional MR results from an imbalance between tethering forces—annular dilatation, LV dilatation, papillary muscle displacement, and LV sphericity—and closing forces—reduction of LV contractility, global LV dyssynchrony, papillary muscle asynchrony, and altered mitral systolic annular contraction.3 CRT acutely reduces functional MR by increasing closing forces with an improvement in LV dP/dt4 and by improving co-ordinated timing of mechanical activation of papillary muscle insertion sites.5 This benefit appeared to be dependent on continued pacing because withholding pacing resulted in an immediate loss of effect and recurrence of MR.6
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Piérard et al. (2007) conducted an editorial in Heart failure with intraventricular conduction delay and functional mitral regurgitation. Cardiac resynchronization therapy (CRT) was evaluated. Cardiac resynchronization therapy acutely reduces functional mitral regurgitation by increasing closing forces and improving coordinated timing of mechanical activation of papillary muscles.
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