Abstract 3079: Mechanism of Improvement in Mitral Regurgitation After Cardiac Resynchronization Therapy
Introduction: The aim of the current study was to evaluate the relationship between presence of LV dyssynchrony at baseline and improvement in mitral regurgitation (MR) acutely and late after cardiac resynchronization therapy (CRT).
Methods: Sixty-eight consecutive patients (ejection fraction 23±8%, 57% ischemic cardiomyopathy) with at least moderate MR were included. Echocardiography was performed at baseline, one day after CRT initiation and at 6 months follow-up. MR severity was graded semi-quantitatively (mild = jet area/LA area <10%, moderate = jet area/LA area 10 –20%, moderately severe = jet area/LA area 20 – 45%, and severe = jet area/LA area >45%) and improvement in MR was defined as improvement of at least 1 grade. Speckle tracking radial strain was used to assess LV dyssynchrony at baseline and defined as the maximum delay between the 6 LV segments.
Results: The majority of patients improved in MR after CRT, with 43% improving immediately after CRT (“early responders”) and 20% improving late after 6 months of CRT (“late responders”). Early and late responders had similar extent of LV dyssynchrony at baseline (209±115 ms vs. 190±118 ms, P=NS); however, a different distribution of site of latest activation was seen; the site of latest activation in early responders was mostly inferior (64%) or posterior (36%), adjacent to the posterior papillary muscle, whereas the lateral wall was the latest activated segment in late responders (92%).
Conclusions: Presence of baseline LV dyssynchrony is related to improvement in MR after CRT. If LV dyssynchrony involves the posterior papillary muscle an immediate reduction in MR can be expected, whereas in patients with LV dyssynchrony not involving the posterior papillary muscle late improvement in MR can be expected.