Response of secondary mitral regurgitation to cardiac resynchronization therapy: Is the atrium to blame?

Secondary mitral regurgitation (MR) is common in patients eligible for cardiac resynchronization therapy (CRT). The prevalence is estimated at between 15% in New York Heart Association (NYHA) functional class I–II patients and 40% in NYHA class III–IV patients. 1 Daubert C. Behar N. Martins R.P. Mabo P. Leclercq C. Avoiding non-responders to cardiac resynchronization therapy: a practical guide. Eur Heart J. 2017; 38: 1463-1472 PubMed Google Scholar The mechanisms underlying secondary MR in this population are multifactorial. Left ventricular (LV) and mitral annulus dilation due to ischemic or nonischemic cardiomyopathy impair leaflet coaptation of structurally normal mitral valves, resulting in functional MR. More specifically in CRT candidates, mechanical dyssynchrony, together with LV dysfunction, contributes to apical and lateral papillary muscle displacement, resulting in leaflet tethering and reduced valve closing forces. 2 Asgar A.W. Mack M.J. Stone G.W. Secondary mitral regurgitation in heart failure: pathophysiology, prognosis, and therapeutic considerations. J Am Coll Cardiol. 2015; 65: 1231-1248 Crossref PubMed Scopus (296) Google Scholar Apart from classic ventricular mechanisms, left atrial (LA) enlargement may also play a role by contributing to mitral annulus dilation and reduced leaflet coaptation, independent of LV dysfunction. 3 Gertz Z.M. Raina A. Saghy L. Zado E.S. Callan D.J. Marchlinski F.E. Keane M.G. Silvestry F.E. Evidence of atrial functional mitral regurgitation due to atrial fibrillation: reversal with arrhythmia control. J Am Coll Cardiol. 2011; 58: 1474-1481 Crossref PubMed Scopus (263) Google Scholar In patients with atrial fibrillation (AF), improvement in MR severity has been observed after sinus rhythm restoration. 3 Gertz Z.M. Raina A. Saghy L. Zado E.S. Callan D.J. Marchlinski F.E. Keane M.G. Silvestry F.E. Evidence of atrial functional mitral regurgitation due to atrial fibrillation: reversal with arrhythmia control. J Am Coll Cardiol. 2011; 58: 1474-1481 Crossref PubMed Scopus (263) Google Scholar Impact of atrial fibrillation on improvement of functional mitral regurgitation in cardiac resynchronization therapyHeart RhythmVol. 15Issue 12PreviewFunctional mitral regurgitation (FMR) and atrial fibrillation (AF) are frequent heart failure (HF) complications. Cardiac resynchronization therapy (CRT) can improve FMR; however, little is known about the influence of AF on FMR improvement. Full-Text PDF