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Background: Biventricular (BiV) pacing increases transmural repolarization heterogeneity due to epicardial to endocardial conduction from the left ventricular (LV) lead. However, limited evidence is available on concomitant changes in ventricular depolarization and repolarization and long‐term outcomes of BiV pacing. Therefore, we investigated associations of BiV pacing‐induced concomitant changes in ventricular depolarization and repolarization with mortality (i.e., LV assist device, heart transplantation, or all‐cause mortality) and sustained ventricular arrhythmia endpoints. Methods: Consecutive BiV‐defibrillator recipients with digital preimplantation and postimplantation electrocardiograms recorded between 2006 and 2015 at Duke University Medical Center were included. We calculated changes in QRS duration and corrected JT (JTc) interval and split them by median values. For simplicity, these variables were named QRSdecreased (≤ −12 ms), QRSincreased (> –12 ms), JTcdecreased (≤22 ms), and JTcincreased (> 22 ms) and subsequently used to construct four mutually exclusive groups. Results: We included 528 patients (median age, 68 years; male, 69%). No correlation between changes in QRS duration and JTc interval was observed (P =.295). Compared to QRSdecreased/JTcincreased, increased risk of the composite mortality endpoint was associated with QRSdecreased/JTcdecreased (hazard ratio [HR] = 1.62; 95% confidence interval [CI] = 1.09‐2.43), QRSincreased/JTcdecreased (HR = 1.86; 95% CI = 1.27‐2.71), and QRSincreased/JTcincreased (HR = 2.25; 95% CI = 1.52‐3.35). No QRS/JTc group was associated with excess sustained ventricular arrhythmia risk (P =.400). Conclusion: Among BiV‐defibrillator recipients, QRSdecreased/JTcincreased was associated with the most favorable long‐term survival free of LV assist device, heart transplantation, and sustained ventricular arrhythmias. Our findings suggest that improved electrical resynchronization may be achieved by assessing concomitant changes in ventricular depolarization and repolarization. [ABSTRACT FROM AUTHOR]

Background: Changes in left ventricular (LV) activation after cardiac resynchronization therapy (CRT) influence survival but are difficult to quantify noninvasively. Methods and Results: We studied 527 CRT patients to assess whether noninvasive quantification of changes in LV activation, defined by change (Δ) in QRS area (QRSA), can predict outcomes after CRT. The study outcome was time until LV assist device(LVAD), cardiac transplant, or death. The three‐dimensional QRSA was measured from clinical 12 lead ECGs which were transformed into vectorcardiograms using the Kors method. QRSA was calculated as (QRSx2 + QRSy2 + QRSz2)1/2; ΔQRSA was calculated as post‐QRSA minus pre‐QRSA, where a negative value represents a reduction in LV activation delay. Kaplan–Meier plots and multivariable Cox proportional hazards models were used to relate ΔQRSA area with outcomes after stratifying the population into quartiles of ΔQRSA. The median baseline QRSA of 93.6 µVs decreased to 59.7 µVs after CRT. Progressive reductions in QRSA with CRT were associated with a lower rate of LVAD, transplant, or death across patient quartiles (P < .001). In Cox regression analyses, ΔQRSA was associated with outcomes independent of QRS morphology and other clinical variables (Q1[greatest decrease] vs Q4[smallest change=reference], HR 0.45, CI, 0.30‐0.70, P < .001). There was no interaction between ΔQRSA and QRS morphology. Conclusions: CRT induced ΔQRSA was associated with clinically meaningful changes in event‐free survival. ΔQRSA may be a novel target to guide lead implantation and device optimization. [ABSTRACT FROM AUTHOR]

Background: PR interval prolongation is associated with poor outcome after cardiac resynchronization therapy (CRT) among patients with left bundle branch block (LBBB) but the mechanisms are unknown. We investigated clinical outcomes, electrocardiogram (ECG), and echocardiogram changes after CRT by PR interval. Methods: This is a retrospective study of CRT recipients with a baseline ejection fraction ≤35% and ECG showing sinus rhythm and LBBB. Patients were stratified by baseline PR interval quartile and the primary combined endpoint was time to heart transplantation, left ventricular assist device (LVAD) implantation, or death. ECG, echocardiogram, and clinical variables were compared to identify mechanisms for observed differences in outcomes. Results: Of 291 eligible patients, the mean age was 65 years, 60% were male, and 19% had prior atrial fibrillation. Patients with PR prolongation (quartile 4, PR > 200 ms) more frequently had a history of atrial fibrillation, coronary artery bypass graft surgery, prior implantable cardioverter defibrillator implantation, and use of amiodarone than patients in PR quartiles 1‐3. A PR > 200ms was associated with an adjusted hazard ratio of 1.7 (95% CI: 1.1‐2.5) for the primary endpoint. Patients with PR > 200 ms had less reduction in QRS duration and QRS area after CRT while having more increase in QT and QTc intervals than patients with PR ≤ 200 ms. No major differences were observed in echocardiography by baseline PR interval quartiles. Conclusions: PR prolongation predicts shorter survival free of heart transplantation or LVAD implantation in patients with LBBB. This may be due to inadequate ventricular resynchronization. [ABSTRACT FROM AUTHOR]

Background: Use of echocardiography (echo) has exponentially increased in recent decades. Concerned about this scientific society developed appropriate use criteria (AUC). Clinical management still suffers geographical variations, and no objective data are available about echo AUC in developing countries. We aimed to evaluate (1) the appropriateness of referrals and (2) their relation to changes in clinical decision management. Methods: Prospective analysis of referrals from January to December 2014. Appropriateness and endpoints analyzed in different time points from medical archives. Endpoints: (1) change in the diagnosis, (2) indication for another method to complete the diagnosis, (3) change in clinical treatment, (4) indication for a treatment intervention, or (5) no change in management. Descriptive statistical analysis, Fisher's or chi‐square tests, and Cox regression used as appropriate (significance if P < .05). Results: One thousand one hundred referrals were analyzed (55.5 ± 16.1 years, 44.6% male). 80.5% of referrals were appropriate (A), 11.2% “Rarely Appropriate” (RA), and 8.3% “May Be Appropriate” (MBA). Proportion of (A) did not differ between modalities (TTE‐80.5% vs TEE‐87.7% vs STR‐81.2%, P = .67). (A) referrals were more related to clinical decision than (RA)+(MBA) (38.9% [A] vs 15% [RA]+[MBA], P < .001). The most frequent clinical indications of (RA) and (MBA) TTE were reevaluation of ventricular function without clinical change (AUC 10 and 11) and search of infectious endocarditis when low clinical probability (53). Conclusions: In a developing country, appropriateness of echo was similar to the United States and Europe. However, a significant proportion of referrals were still (RA) or (MBA), with no effect in clinical management. Controlling referrals 10, 11, and 53 can optimize echo use in developing countries. [ABSTRACT FROM AUTHOR]

Background Some patients with RBBB may respond to cardiac resynchronization therapy (CRT). However, little is known regarding the electromechanical substrate for CRT and whether this is the optimal pacing strategy. Methods This was a pilot prospective double crossover randomized controlled clinical study comparing ventricular back up pacing (VVI-40), RV fusion pacing (DDD-40, RV only), and biventricular (BIV) pacing (DDD-40 BIV) in nine patients with RBBB and depressed EF. The study compared the frequency of dyssynchrony on baseline echocardiogram in patients with RBBB (n = 4), RBBB + anterior MI (RBBB with left axis deviation + left ventricular (LV) anterior wall thinning, n = 3), and RBBB + LAFB (RBBB with left axis deviation without LV anterior wall thinning n = 2). Echocardiographic assessment of LV dyssynchrony, LV size, and LV function was repeated after 6 months in each pacing mode. Results Patients with RBBB + LAFB demonstrated baseline echocardiographic dyssynchrony between the LV anterior and inferior wall. Both DDD-40 RV-only pacing and DDD-40 BIV pacing resulted in improved LV function and clinical status compared to VVI-40 back up pacing. Patients with RBBB alone and RBBB with anterior MI had no baseline dyssynchrony and CRT using either RV only or BIV pacing resulted in LV dilation, worsened left ventricular ejection fraction and worsened clinical status compared to VVI-40 back up pacing. Conclusion Patients with RBBB, left axis deviation, and no prior anterior MI may have LV dyssynchrony between the anterior and inferior walls that is correctable with CRT. [ABSTRACT FROM AUTHOR]

Background Optimization of the interventricular delay (VV-optimization) in cardiac resynchronization therapy (CRT) patients can be performed by evaluation of mechanical dyssynchrony. However, there is no consensus on which method to use. In this study, three conceptually different methods were evaluated. Methods Thirty consecutive CRT patients were included. At day 1, patients were atrioventricular and VV optimized by left ventricular outflow tract (LVOT) velocity time integral (VTI). At 6 months, 2D strain (2DS) echocardiography and tissue Doppler imaging (TDI) was performed at six different VV-programming delay in steps of 20 ms. LVOT and three indices of dyssynchrony were evaluated at each setting: standard deviation (SD) of time-to-peak strain in 12 segments (2DS-SD), SD of time-to-peak velocities in 12 segments (TDI-SD), and maximal activation delay (AD-max) by cross-correlation analysis (XCA) of TDI-derived myocardial acceleration curves. Results Feasibility was 90% for 2DS-SD and TDI-SD and 97% for AD-max. Coefficients of variation for intraobserver variability were 13% for 2DS-SD, 11% for TDI-SD, and 6% for AD-max. A relative increase in LVOT VTI > 10% was observed in 5/12 (42%) nonresponders and 7/18 (39%) responders to CRT. Optimization by all three dyssynchrony indices significantly increased LVOT VTI compared to simultaneous pacing and optimal setting at day 1 (P < 0.05, all). LVOT VTI was highest when using AD-max, and AD-max showed the best agreement (k = 0.71). Conclusion VV optimization at 6 months acutely benefits both responders and nonresponders; however, dyssynchrony indices do not perform equally well. XCA has a high feasibility and reproducibility and appears to be superior to time-to-peak techniques. [ABSTRACT FROM AUTHOR]

Examines the imaging quality of three-dimensional (3D) echocardiography. Two-dimensional echocardiography orientation of the heart; Image orientation of 3D echocardiography; Recommended 3D echocardiography basic sections; Image atlas of recommended 3D echocardiography images of the heart.