Improved papillary muscle function attenuates functional mitral regurgitation in patients with dilated cardiomyopathy after cardiac resynchronization therapy

Background: Functional mitral valve regurgitation attenuation after cardiac resynchronization therapy (CRT) in patients with severe heart failure has been attributed to both the increased rate of left ventricular systolic pressure increase and to papillary muscle (PM) recoordinated contraction. We hypothesized that an increase in systolic deformation of the PMs or the adjacent myocardial wall may in part account for this effect, by preventing their outward displacement during systole. Methods. We studied by echocardiography 22 patients with moderate/severe functional mitral valve regurgitation and a mean ejection fraction of 18 +/- 4% at baseline and after implantation of a CRT system. Results. CRT induced a significant reduction of the effective regurgitant orifice area (0.18 +/- 0.11 vs 0.35 +/- 0.17 mm(2), P <.001). Strain improved in both PMs and their adjacent walls, although this improvement was significant only in anterolateral Pm (-16 +/- 4.7 vs -11 +/- 4.3%, P =.02) and posteromedial PM adjacent wall (- 16 +/- 10 vs -8 +/- 4.6%, P =.01). Conclusions. CRT acutely reduces the severity of functional mitral valve regurgitation in patients with heart failure and this effect may be in part attributed to improved strain of PM or adjacent wall.