Mechanism of improvement in mitral regurgitation after cardiac resynchronization therapy.

AIMS: The aim of the current study was to evaluate the relationship between the presence of left ventricular (LV) dyssynchrony at baseline and acute vs. late improvement in mitral regurgitation (MR) after cardiac resynchronization therapy (CRT). METHODS AND RESULTS: Sixty eight patients consecutive (LV ejection fraction 23 +/- 8%) with at least moderate MR (>or=grade 2+) were included. Echocardiography was performed at baseline, 1 day after CRT initiation and at 6 months follow-up. Speckle tracking radial strain was used to assess LV dyssynchrony at baseline. The majority of patients improved in MR after CRT, with 43% improving immediately after CRT, and 20% improving late (after 6 months) after CRT. Early and late responders had similar extent of LV dyssynchrony (209 +/- 115 ms vs. 190 +/- 118 ms, P = NS); however, the site of latest activation in early responders was mostly inferior or posterior (adjacent to the posterior papillary muscle), whereas the lateral wall was the latest activated segment in late responders. CONCLUSION: Current data suggest that the presence of baseline LV dyssynchrony is related to improvement in MR after CRT. LV dyssynchrony involving the posterior papillary muscle may lead to an immediate reduction in MR, whereas LV dyssynchrony in the lateral wall resulted in late response to CRT

Relative merits of left ventricular dyssynchrony, left ventricular lead position, and myocardial scar to predict long-term survival of ischemic heart failure patients undergoing cardiac resynchronization therapy

Background-: The relative merits of left ventricular (LV) dyssynchrony, LV lead position, and myocardial scar to predict long-term outcome after cardiac resynchronization therapy remain unknown and were evaluated in the present study. Methods and results-: In 397 ischemic heart failure patients, 2-dimensional speckle tracking imaging was performed, with comprehensive assessment of LV radial dyssynchrony, identification of the segment with latest mechanical activation, and detection of myocardial scar in the segment where the LV lead was positioned. For LV dyssynchrony, a cutoff value of 130 milliseconds was used. Segments with 50% transmurality, validated in a subgroup with contrast-enhanced magnetic resonance imaging). The LV lead position was derived from chest X-ray. Long-term follow-up includ

Biventricular pacing in chronic heart failure acutely facilitates the arterial baroreflex

Metabolic and mechanical stress in the failing heart activates the cardiac sympathetic afferent reflex (CSAR). It has been demonstrated that cardiac resynchronization therapy (CRT) acutely reduces MSNA in clinical responders. Mechanistically, this beneficial effect might be explained by acute deactivation of the CSAR. In addition to sympathoexcitation, CSAR inhibits the arterial baroreflex at the level of the nucleus tractus solitarii. Hence, in responders, CRT is likely to remove/reduce this inhibition. Therefore, we hypothesized that CRT acutely facilitates the arterial baroreflex. One day after implantation of a CRT device in 32 patients with chronic heart failure (LVEF; 27 +/- 6%), we measured noninvasive baroreflex sensitivity (BRS) and heart rate variability (HRV) in two conditions: CRT device switched on and switched off (on/off order randomized). BRS changes were correlated with the difference in unpaced/paced LVEF, a measure of acute mechanical response to CRT. CRT increased BRS by 35% from 2.96 to 3.79 ms/mmHg (P <0.02) and increased HRV (standard deviation of the intervals between normal beats) from 18.5 to 24.0 ms (P <0.01). The CRT-induced relative change in BRS correlated with the change in LVEF (r = 0.44; P <0.01). In conclusion, CRT acutely increases BRS and HRV. This favorable response of the autonomic nervous system might be caused by CRT-induced CSAR deactivation. Follow-up studies should verify the mechanism of the acute response and the possible predictive value of an acute positive BRS respons

Real-time three-dimensional echocardiography permits quantification of left ventricular mechanical dyssynchrony and predicts acute response to cardiac resynchronization therapy

RT3DE Predicts Acute Response to CRT. Objective: To evaluate the value of real-time three-dimensional echocardiography (RT3DE) to predict acute response to cardiac resynchronization therapy (CRT). Methods: Sixty consecutive heart failure patients scheduled for CRT were included. RT3DE was performed before and within 48 hours after pacemaker implantation to calculate both left ventricular (LV) volumes and LV dyssynchrony. LV dyssynchrony was defined as the standard deviation of the time taken to reach the minimum systolic volume for 16 LV segments (referred to as the systolic dyssynchrony index, SDI). Patients were subsequently divided into acute responders or nonresponders, based on a reduction >= 15% in LV end-systolic volume immediately after CRT. Results: Four patients (7%) were excluded from further analysis because of either suboptimal apical acquisitions or significant translation artifacts. Out of the remaining 56 patients, 35 patients (63%) were classified as acute responders. Baseline characteristics were similar between responders and nonresponders, except for the SDI, which was larger in responders. Moreover, responders demonstrated a significant reduction of SDI immediately after CRT (from 9.7 +/- 4.1% to 3.6 +/- 1.8%, P < 0.0001), whereas SDI did not change in nonresponders (3.4 +/- 1.8% vs 3.1 +/- 1.1%, NS). ROC curve analysis revealed that a cut-off value for SDI of 5.6% yielded a sensitivity of 88% with a specificity of 86% to predict acute echocardiographic response to CRT (AUC 0.96). Conclusion: RT3DE is highly predictive for acute response to CRT (sensitivity 88% and specificity 86%). In addition, RT3DE allows assessment of changes in LV volumes and LV ejection fraction before and after CRT implantation