Native Electrocardiographic QRS Duration after Cardiac Resynchronization Therapy: The Impact on Clinical Outcomes and Prognosis.

BACKGROUND: We investigated whether reversed electrical remodeling (RER), defined as narrowing of the native electrocardiographic QRS duration after cardiac resynchronization therapy (CRT), might predict prognosis and improvement in echocardiographic outcomes. METHODS AND RESULTS: A total of 110 CRT recipients were retrospectively analyzed for the end points of death and hospitalization during 18 ± 3 months. Native QRS durations were recorded at baseline and 6 months after CRT (when pacing was switched off to obtain an electrocardiogram) to determine RER. CRT response and mitral regurgitation (MR) improvement were defined as ≥15% reduction in left ventricular end-systolic volume and absolute reduction in regurgitant volume (RegV) at 6 months, respectively. Overall, 48 patients (44%) had RER, which was associated with functional improvement (77% vs 34%; P < .001) and CRT response (81% vs 52%; P < .001) compared with those without RER. The change in the intrinsic QRS duration correlated with the reduction in RegV (r = 0.51; P < .001) and in tenting area (r = 0.34; P < .001). RER was a predictor of MR improvement (P = .023), survival (P = .043), and event-free survival (P = .028) according to multivariate analyses. CONCLUSIONS: Narrowing of the intrinsic QRS duration is associated with functional and echocardiographic CRT response, reduction in MR, and favorable prognosis after CRT.

Predicting Ventricular Arrhythmias in Cardiac Resynchronization Therapy: The Impact of Persistent Electrical Dyssynchrony.

BACKGROUND: Although response to cardiac resynchronization therapy (CRT) has been conventionally assessed with left ventricular volume reduction, ventricular arrhythmias (ventricular tachycardia/ventricular fibrillation [VT/VF]) are of critical importance associated with unfavorable outcomes even in the "superresponders" to therapy. We evaluated the predictors of VT/VF and the association of residual dyssynchrony during follow-up. METHODS: Ninety-five patients receiving CRT were followed-up for 9 ± 3 months. Post-CRT dyssynchrony was defined as a prolonged QRS duration (QRSd) for persistent electrical dyssynchrony (ED), and a Yu index ≥ 33 ms for persistent mechanical dyssynchrony. The first VT/VF episode, including nonsustained VT detected on device interrogation and/or appropriate antitachycardia pacing or shock for VT/VF, were the end points of the study. RESULTS: Forty-five patients who reached the study end points had significantly lower mean ΔQRS (baseline QRSd - post-CRT QRSd) values than those without VT/VF (-20.8 ± 28.9 ms vs -6.6 ± 30.7 ms, P = 0.022). Both the baseline and post-CRT QRSds, along with the Yu index values, were not different in two groups. Patients with VT/VF were statistically more likely to have persistent ED (38% vs 9%, P = 0.021). Kaplan-Meier curves showed that a negative ΔQRS was associated with a higher incidence of VT/VF during follow-up (P = 0.016). A multivariate Cox model revealed that QRS prolongation was an independent predictor of VT/VF after CRT (P = 0.029). CONCLUSIONS: A negative ΔQRS, also called persistent ED, is associated with VT/VF. Narrowest possible QRSd might be a reliable goal of both implantation and optimization of devices to reduce arrhythmic events after CRT.

Time course of right ventricular remodeling after percutaneous atrial septal defect closure: assessment of regional deformation properties with two-dimensional strain and strain rate imaging.

BACKGROUND: Quantitative assessment of the right ventricular (RV) function in atrial septal defect (ASD) patients before and after closure remains difficult. The aim of this study was to assess the regional RV function in ASD patients, to evaluate the extent and time course of RV remodeling following ASD closure, and to investigate whether any regional difference exists in RV remodeling. METHODS: Twenty patients with ASD and 20 age-matched controls were included. All underwent standard echocardiography and two-dimensional strain (S) and strain rate (SR) imaging by speckle tracking before, and 24 hours and 1 month after the defect closure. RESULTS: Right ventricular S was higher in ASD patients except apical lateral segment S, which was lower when compared with controls. There was no difference in RV SR between ASD patients and controls. RV septal S and SR, and lateral SR decreased in 24 hours after the procedure and remained the same at 1 month. RV lateral basal and mid S decreased and apical S increased in 24 hours after the closure. All 3 segments showed some more increase at 1 month. RV apical S showed strong correlations with systolic pulmonary artery pressure and global RV systolic function indices. CONCLUSIONS: Chronic volume overload in ASD patients causes alterations in RV deformation. Percutaneous closure results in rapid remodeling and normalization of RV deformation. The major geometrical and deformational changes are completed in 24 hours. Lateral wall S seems to reflect the RV deformational changes due to volume loading and unloading better than SR in ASD patients.

Effect of cardiac resynchronization therapy on mitral valve geometry: a novel aspect as "reversed mitral remodeling".

Amelioration of the valvular geometry is a possible mechanism for mitral regurgitation (MR) improvement in patients receiving cardiac resynchronization therapy (CRT). We aimed to establish the precise definition, incidence, and predictors of reversed mitral remodeling (RMR), as well as the association with MR improvement and short-term CRT outcome. Ninety-five CRT recipients were retrospectively evaluated for the end-point of "MR response" defined as the absolute reduction in regurgitant volume (RegV) at 6 months. To identify RMR, changes in mitral deformation indices were tested for correlation with MR response and further analyzed for functional and echocardiographic CRT outcomes. Overall, MR response was observed in 50 patients (53%). Among the echocardiographic indices, the change in tenting area (TA) had the highest correlation with the change in RegV (r = 0.653, p < 0.001). The mean TA significantly decreased in MR responders (4.15 ± 1.05 to 3.67 ± 1.01 cm2 at 6 months, p < 0.001) and increased in non-responders (3.68 ± 1.04 to 3.98 ± 0.97 cm2, p = 0.014). The absolute TA reduction was used to identify patients with RMR (47%) which was found to be associated with higher rates of functional improvement (p = 0.03) and volumetric CRT response (p = 0.036) compared to those without RMR. Non-ischemic etiology and the presence of LBBB independently predicted RMR at multivariate analysis. In conclusion, reduction in TA is a reliable index of RMR, which relates to MR response, and functional and echocardiographic improvement with CRT. LBBB and non-ischemic etiology are independent predictors of RMR.

QRS prolongation after cardiac resynchronization therapy is a predictor of persistent mechanical dyssynchrony.

PURPOSE: Prolonged QRS duration is the main selection criterion for cardiac resynchronization therapy (CRT) which ameliorates left ventricular mechanical dyssynchrony (MD). However, consequences of post-CRT QRS prolongation and residual MD have been poorly evaluated. We aimed to define the predictors of persistent MD and hypothesized that CRT-induced QRS change (ΔQRS) might have an impact on residual MD after CRT. METHODS: A total of 80 patients receiving CRT were included in the study. ΔQRS was calculated as the difference between the baseline and paced QRS intervals. Residual MD was assessed early after device implantation with a longitudinal dyssynchrony index (Yu index). Significant MD was defined as a Yu index ≥ 33 msec. Two groups were created based on residual MD and compared according to clinical, electrocardiographic and echocardiographic features. RESULTS: Patients with persistent MD had longer paced QRS durations (182.5 ± 16.2 vs. 165.4 ± 22.5 msec, p = 0.03) and were less likely to have left ventricular (LV) leads located in the posterolateral vein (53 % vs. 85 %, p = 0.002). The linear correlation between the ΔQRS and the Yu index values was modest (Spearman's rho = -0.341, p = 0.002); additionally, a prolonged QRS was strongly associated with MD after CRT (p = 0.00008). Both LV lead localization and CRT-induced QRS prolongation emerged as the significant predictors of persistent MD. A biventricularly paced QRS more than 10 msec longer than the pre-paced QRS width was predictive of persistent MD after CRT (sensitivity = 80 %, specificity = 62 %). CONCLUSIONS: ΔQRS was found to be associated with residual MD after CRT. Ten milliseconds of QRS prolongation predicted persistent MD after CRT.

Effect of QRS Narrowing After Cardiac Resynchronization Therapy on Functional Mitral Regurgitation in Patients With Systolic Heart Failure.

The determinants of improvement in functional mitral regurgitation (FMR) after cardiac resynchronization therapy (CRT) remain unclear. We evaluated the predictors of FMR improvement and hypothesized that CRT-induced change in QRS duration (ΔQRS) might have an impact on FMR response after CRT. One hundred ten CRT recipients were enrolled. CRT response (≥ 15 reduction in left ventricular end-systolic volume) and FMR response (absolute reduction in FMR volume) were assessed with echocardiography before and 6 months after CRT. The study end points included all-cause death or hospitalization assessed in 12 ± 3 months (range 1 to 18). A total of 71 patients (65%) responded to CRT at 6 months. FMR response was observed in 49 (69%) of the CRT responders and 8 (20%) of the CRT nonresponders (p <0.001). Although the baseline QRS durations were similar, the paced QRS durations were shorter (p = 0.012) and the ΔQRS values were greater (p = 0.003) in FMR responders compared with FMR nonresponders. There was a linear correlation between ΔQRS and change in regurgitant volume (r = 0.49, p <0.001). At multivariate analysis, baseline tenting area (p = 0.012) and ΔQRS (p = 0.028) independently predicted FMR response. A ΔQRS ≥ 20 ms was related to CRT response, FMR improvement, and lower rates of death or hospitalization during follow-up (p values <0.05). In conclusion, QRS narrowing after CRT independently predicts FMR response. A ΔQRS ≥ 20 ms after CRT is associated with a favorable outcome in all clinical end points.