Opposing Wall Delay Research Articles

R-Rʹ interval in the left bundle branch block predicts long-term outcomes after cardiac resynchronization therapy by estimating greater mechanical dyssynchrony and viable myocardium

BackgroundTypical left bundle branch block (LBBB) shows 2 peaks of the R wave, which reflect activation reaching the interventricular septum (R) and posterolateral wall (Rʹ) sequentially. ObjectiveThe purpose of this study was to investigate the relationship among R-Rʹ interval (RRʹ), mechanical dyssynchrony, extent of viable myocardium, and long-term outcomes in cardiac resynchronization therapy (CRT) candidates. MethodsThe study enrolled 49 patients (34 men; mean age: 69 ± 11 years) with LBBB who received CRT. The LBBB definition used requires the presence of mid-QRS notching in leads V1, V2, V5, V6, I, and aVL. Baseline evaluations were QRS duration (QRSd) and RRʹ measured from the 12-lead electrocardiogram; eyeball dyssynchrony (apical rocking and septal flash) and opposing-wall delay by speckle tracking from echocardiography, and extent of viable myocardium assessed by thallium-201 single-photon emission computed tomography. Primary outcomes included the combination of all-cause death and heart failure–related hospitalization. ResultsRRʹ predicted volumetric response better than QRSd (area under the curve 0.73 vs 0.67, respectively). The long RRʹ group (≥48 ms) revealed more frequent eyeball dyssynchrony and significantly greater radial (SL) and circumferential dyssynchrony (AP and SL) and %viable segment than the short RRʹ group. In multivariate regression analysis, only RRʹ ≥48 ms was independently associated with higher event-free survival rates following CRT (hazard ratio 0.21; P = .014). ConclusionThese findings suggest that RRʹ in complete LBBB was associated with mechanical dyssynchrony, extent of viable myocardium, and long-term outcomes following CRT.

Abstract 13141: Max Opposing Wall Delay in Right Atrial Strain Can Be a Prognostic Factor at 30-day Mortality in Submassive Pulmonary Embolism

Background: Submassive pulmonary embolism (sPE) is common and associated with significant mortality. Right ventricular dyssynchrony caused by sPE were reported previously. However, limited studies have evaluated dyssynchrony of right atrium (RA) strain in the setting of sPE. The purpose of this study was to identify the potential role of RA dyssynchrony in patients with sPE. Methods: 201 patients with sPE were assessed in this retrospective cohort study. All echocardiograms were completed within 48 hours of diagnosis. RA strain was analyzed retroactively using TOMTEC®. RA dyssynchrony was defined as absolute max opposing wall delay which was time interval between peak lateral and septal wall strain in RA after R-R interval correction (maxOWD) (Figure 1). The primary outcome was 30-day all-cause mortality. Results: 201 patients included in the study. Mortality rate of 11.4% was seen at 30 days. Median maxOWD in survivors was significantly low compared to that in non-survivors (4.35 vs 16.20, p < 0.001). Univariable and Multivariable analysis showed maxOWD was an independent factor to predict short-term mortality. Receiver operating characteristics (ROC) analysis revealed area under the curve was 0.795 and best cutoff value was 10.43. Using the cutoff value, Kaplan-Meier curves depicted survival rate in patients with maxOWD > 10.43 was significantly lower than those with maxOWD ≤ 10.43. (Hazard Ratio 7.84, p < 0.001) (Figure 2) Conclusions: Max opposing wall delay after R-R interval correction in RA strain has significant prognostic value in assessing risk of mortality in patients with submassive PE.

PO-05-043 RIGHT VENTRICULAR POSITIONING OF LEADLESS PACEMAKER MAY INFLUENCE LEFT VENTRICULAR ELECTROMECHANICAL SYNCHRONY

Leadless pacemakers (LP) reduce certain complications of conventional pacemakers, yet limitations of single chamber right ventricular (RV) pacing remain, including pacing-induced dyssynchrony. The Micra LP is positioned in RV septum, avoiding the free wall to minimize perforation, and the location is primarily determined by capture threshold and sensitivity. Whether positioning of the LP in the mid to upper septum vs. apical septum affects the degree of left ventricular (LV) synchrony is yet to be determined. We sought to establish whether the Micra position on the RV septum affects LV synchrony, using strain imaging by speckle-tracking echocardiography. Between May 2019 and February 2022, 53 consecutive patients implanted with Micra LP were screened. Of those, eleven patients were found to be 100% paced and have an adequate quality transthoracic echocardiogram (TTE) for strain analysis. Chest imaging and 12-lead electrocardiogram (EKG) were used to identify the implantation site (apical vs. mid to high RV septum). The LV focused apical views were processed with Tomtec software to acquire strain variables including left ventricle mechanical dispersion (LVMD) and maximal opposing wall delays from an 18 segment LV model. QRS duration (QRSd) was obtained from the paced EKG. The Mann-Whitney U test and Fisher’s exact test were used to compare the independent groups. All analyses were performed using SPSS Ver 29.0 (IBM Corporation, Armonk, NY). Electrical dyssynchrony measured by QRSd showed a tendency of longer QRSd in the apical septal group (n= 5) compared to higher septal group (n= 6), but it was not statistically significant (159.6 +/- 13.8 vs. 148.33 +/- 16.15, p = 0.302). Ejection fraction showed no significant difference between two groups (median 64 vs. 60, p = 0.879). Degree of mitral regurgitation also showed no significant difference (U = 11.5, p = 0.537). Higher septal placement resulted in improved mechanical LV synchrony compared to the apical placement as measure by lower LVMD and shorter opposing wall delay (U = 2 and 3, p = 0.017 and 0.03 respectively). The Implantation site of a Micra LP displays a difference in speckle tracking derived LV mechanical strain, which was improved with higher septal positioning. This may have consequences on cardiac mechanical function in patients requiring continuous pacing. Larger studies are needed to determine whether these preliminary findings may be generalized to a larger population.

Ventricular dyssynchrony late after the Fontan operation is associated with decreased survival

BackgroundVentricular dyssynchrony and its relationship to clinical outcomes is not well characterized in patients following Fontan palliation. MethodsSingle-center retrospective analysis of cardiac magnetic resonance (CMR) imaging of patients with a Fontan circulation and an age-matched healthy comparison cohort as controls. Feature tracking was performed on all slices of a ventricular short-axis cine stack. Circumferential and radial strain, strain rate, and displacement were measured; and multiple dyssynchrony metrics were calculated based on timing of these measurements (including standard deviation of time-to-peak, maximum opposing wall delay, and maximum base-to-apex delay). Primary endpoint was a composite measure including time to death, heart transplant or heart transplant listing (D/HTx). ResultsA total of 503 cases (15 y; IQR 10, 21) and 42 controls (16 y; IQR 11, 20) were analyzed. Compared to controls, Fontan patients had increased dyssynchrony metrics, longer QRS duration, larger ventricular volumes, and worse systolic function. Dyssynchrony metrics were higher in patients with right ventricular (RV) or mixed morphology compared to those with LV morphology. At median follow-up of 4.3 years, 11% had D/HTx. Multiple risk factors for D/HTx were identified, including RV morphology, ventricular dilation, dysfunction, QRS prolongation, and dyssynchrony. Ventricular dilation and RV morphology were independently associated with D/HTx. ConclusionsCompared to control LVs, single right and mixed morphology ventricles in the Fontan circulation exhibit a higher degree of mechanical dyssynchrony as evaluated by CMR-FT. Dyssynchrony indices correlate with ventricular size and function and are associated with death or need for heart transplantation. These data add to the growing understanding regarding factors that can be used to risk-stratify patients with the Fontan circulation.

5943Mechanistic insights of papillary muscle dyssynchrony mediated function mitral regurgitation and modulation by cardiac resynchronization

Abstract Abstract Background Mechanistic features of functional mitral regurgitation (FMR) include papillary muscle displacement due to left ventricular remodeling. Intraventricular conduction delay might further augment this condition by introducing interpapillary muscle dyssynchrony. Objectives To define this mechanism as a major contributing factor in FMR and prove the reversibility of FMR by interpapillary muscle resynchronization. Methods We enrolled 269 chronic HFrEF patients with conduction delay and comprehensively assessed dyssynchrony by complementary echocardiographic techniques. Opposing wall delay, calculated by speckle tracking, was determined as the time difference between peak longitudinal strain of the mid-anterior and inferior wall from a 2-chamber view. Furthermore, opposing wall delay was assessed as the time difference between peak strain values from tissue Doppler velocity-coded data of the mid-inferior septal and mid-lateral wall segments. Results Patients with severe FMR had markedly increased interpapillary longitudinal dyssynchrony (160ms [IQR 120–200]) compared to those with moderate (70ms [IQR 40–110]), no, or mild FMR (60ms [IQR 30–100]; P<0.001). Increased interpapillary muscle dyssynchrony was correlated with effective regurgitant orifice area (P<0.001; Figure A), regurgitant volume (P<0.001, Figure B) and vena contracta width (P<0.001, Figure C). Restoration of longitudinal papillary muscle synchronicity by cardiac resynchronization therapy (CRT) was correlated with FMR regression, as reflected by the reduction in regurgitant volume (P<0.001) and vena contracta width (P<0.001). Conversely, the improvement of FMR was associated with improved interpapillary radial (P=0.006) and longitudinal (P<0.001) dyssynchrony. The improvement of dyssynchrony-mediated FMR signified a better prognosis compared to no improvement in FMR during the 8-year follow-up period even after comprehensive adjustment by a bootstrap-selected confounder model (adj. HR of 0.41; 95% CI 0.18–0.91; P=0.028; Figure D). The results remained virtually unchanged after adjustment for left bundle branch block. Figure 1. Dyssynchrony-FMR-CRT Conclusion Intraventricular dyssynchrony introduces unequal contraction by papillary muscle bearing walls, which has an adverse effect on FMR. CRT can effectively restore interpapillary balance and thus create a less tented leaflet configuration, resulting in a clinically meaningful reduction of FMR. The restoration of papillary muscle synchronicity in dyssynchrony-mediated FMR translates into a significantly better prognosis.

The Detrimental Effect of RA Pacing on LA Function and Clinical Outcome in Cardiac Resynchronization Therapy

ObjectivesThis study assessed the impact of right-atrial (RA) pacing on left-atrial (LA) physiology and clinical outcome. BackgroundData for the effects of RA pacing on LA synchronicity, function, and structure after cardiac resynchronization therapy (CRT) are scarce. MethodsThe effect of RA pacing on LA function, morphology, and synchronicity was assessed in a prospective imaging cohort of heart failure (HF) patients in sinus rhythm with a guideline-based indication for CRT. Additionally, in a retrospective outcome cohort of consecutive HF patients undergoing CRT implantation, the relationship to RA pacing was assessed using various outcome endpoints. High versus low atrial pacing burden was defined as atrial pacing above or below 50% in both cohorts. ResultsA total of 36 patients were included in the imaging cohort (68 ± 11 years of age). Six months after CRT, patients with high RA pacing burden showed less improvement in LA maximum and minimum volumes and total emptying fraction (p < 0.05). Peak atrial longitudinal strain and reservoir and booster strain rates but not conduit strain rate improved after CRT in patients with low RA pacing burden but worsened in patients with high RA pacing burden (p < 0.05 for all). A high RA pacing burden induced significant intra-atrial dyssynchrony (maximum opposing wall delay: 44 ± 13 ms vs. 97 ± 17 ms, respectively; p = 0.022). A total of 569 patients were included in the outcome cohort. After covariate adjustments were made, a high RA pacing burden was associated with reduced LV reverse remodeling (β = 8.738; 95% confidence interval [CI]: 3.101 to 14.374; p = 0.002) and new-onset or recurrent atrial fibrillation (41% vs. 22%, respectively, at a median of 31 months [range 22 to 44 months follow-up]; p < 0.001). There were no differences in time to first HF hospitalization or all-cause mortality (p = 0.185) after covariate adjustment. However, in a recurrent event analysis, HF readmissions were more common in patients exposed to a high RA pacing burden (p = 0.003). ConclusionsRA pacing in CRT patients negatively influences LA morphology, function, and synchronicity, which is associated with worse clinical outcome, including diminished LV reverse remodeling, increased risk for new-onset or recurrent AF and heart failure readmission. Strategies reducing RA pacing burden may be warranted.

Assessment of Left Ventricular Mechanical Dyssynchrony in Left Bundle Branch Block Patients with and Without Heart Failure by Tissue Doppler Imaging

Introduction: Large number of patients with heart failure (HF) have left bundle branch block (LBBB). Most precise method for identification of intraventricular dyssynchrony is tissue Doppler imaging (TDI). Purpose of this research was to compare left ventricular (LV) mechanical dyssynchrony in LBBB patients with and without HF and to compare various methods of LV systolic dyssynchrony assessment by TDI. Materials and Methods: One hundred and sixteen patients with a diagnosis of LBBB were included in the study. All patients underwent conventional two-dimensional echocardiography for global LV function assessment. LV systolic dyssynchrony was measured by opposing wall delay, maximum delay, and Yu index. LBBB patients were grouped into four classes according to their LV function and the presence or absence of HF, normal LV function without HF (Group A), normal LV function with HF (Group B), LV dysfunction with HF (Group C), and LV dysfunction without HF (Group D). Results: LV systolic dyssynchrony was significantly higher (P &lt;0.001) in Group C and D as compared to Group A and B. LV systolic dyssynchrony was significant higher in Group C and D as compared to Group A and B by using opposing wall delay (P &lt;0.001), Yu index (P &lt;0.001), and maximum delay (P &lt;0.001) imaging criteria. Mean Yu index (P &lt;0.001) and mean maximum delay (P &lt;0.001) were significantly higher in Group C and D as compared to Group A and B. Conclusions: LV systolic dyssynchrony was more common in LBBB patients with LV dysfunction than those with normal LV function, irrespective of the presence or absence of HF.

Improvement in left ventricular intrinsic dyssynchrony with cardiac resynchronization therapy.

Objective:Cardiac resynchronization therapy (CRT) has been shown to induce a structural and electrical remodeling; the data on whether left ventricle (LV) reverse remodeling is associated with restitution of intrinsic contraction pattern are unknown. In this study, we investigated the presence of improvement in left ventricular intrinsic dyssynchrony in patients with CRT.Methods:A total of 45 CRT recipients were prospectively studied. Dyssynchrony indexes including interventricular mechanical delay (IVMD) and tissue Doppler velocity opposing-wall delay (OWD) as well as QRS duration on 12-lead surface electrocardiogram were recorded before CRT device implantation. After 1 year, patients with chronic biventricular pacing were reprogramed to VVI 40 to allow the resumption of native conduction and contraction pattern. After 4–6 h of intrinsic rhythm, QRS duration and all echocardiographic measurements were recorded. Dyssynchrony was defined as IVMD >40 ms and OWD >65 ms. CRT response was defined by a ≥15% reduction in left ventricular end-systolic volume (LVESV) at a 12-month follow-up.Results:Thirty-two patients (71%) showed response to CRT. The native QRS duration reduced significantly from 150±12 ms to 138±14 ms (p<0.001), and dyssynchrony indexes showed a significant improvement only in responders. The mean OWD reduced from 86±37 ms to 50±29 ms (p<0.001), and the mean IVMD decreased from 55±22 ms to 28±22 ms (p<0.001) in responders. The reduction in LVESV was significantly correlated with ΔOWD (r=0.47, p=0.001), ΔIVMD (r=0.45, p=0.001), and ΔQRS (r=0.34, p=0.022).Conclusion:Chronic CRT significantly improves LV native contraction pattern and causes reverse remodeling in dyssynchrony.

Echocardiographic evaluation of cardiac dyssynchrony in patients with congestive heart failure.

The present study investigated the application of echocardiography to evaluation of cardiac dyssynchrony in patients with congestive heart failure (CHF). A total of 348 consecutive CHF patients who were admitted for cardiac resynchronization (CRT) and presented with low ejection fraction (EF) and wide QRS duration were enrolled in this study, along with 388 healthy individuals. Dyssynchrony was assessed based on filling time ratio (FT/RR), left ventricular pre-ejection delay (PED), interventricular mechanical delay (IVMD), longitudinal opposing wall delay (LOWD) and radial septal to posterior wall delay (RSPWD). Response to CRT was defined as a ≥15% increase in EF. The results showed that FT/RR was decreased while PED, IVMD, LOWD and RSPWD were increased in the CHF group compared with the control group (P<0.01). In the CHF group, FT/RR was negatively correlated with the QRS duration, LV end-diastolic diameter (LVESd), LV end-diastolic volume (LVEDV) and LV end-systolic volume (LVESV) (P<0.01), but positively with the LVEF (P<0.01). Additionally, PED, IVMD, LOWD and RSPWD were positively correlated with the QRS duration, LVESd, LVEDV and LVESV (P<0.01), but negatively with the LVEF (P<0.01). The CHF group was divided into three subgroups according to the varying degrees of LVEF. FT/RR decreased successively from the LVEF-1 group to the LVEF-2 group to the LVEF-3 group, while the PED, IVMD, LOWD and RSPWD successively increased in the same order (P<0.01). The CHF group was divided into three subgroups according to the varying degrees of QRS duration, and FT/RR decreased successively in a sequence from the QRS-1 group to the QRS-2 group to the QRS-3 group, while the PED, IVMD, LOWD and RSPWD successively increased in the same order (P<0.01). Speckle tracking radial dyssynchrony ≥130 ms was predictive of an EF response in patients in QRS-1 group (78% sensitivity, 83% specificity), those in QRS-2 group (83% sensitivity, 77% specificity) and in QRS-3 group (89% sensitivity, 79% specificity). In conclusion, echocardiography is a convenient and sensitive method for evaluating cardiac dyssynchrony in patients with CHF.

Cardiac Resynchronization Therapy Plus Coupled Pacing Improves Acutely Myocardial Function in Heart Failure Patients

Coupled pacing (CP), which consists of an additional beat delivered after ventricular refractory period, has been proposed to reduce ventricular rate and increase ventricular contractility. We hypothesized that CP may be added to cardiac resynchronization therapy (CRT) to improve CRT effect in heart failure (HF) patients. The study included 20 consecutive HF patients in sinus rhythm referred for CRT-defibrillator (CRT-D) implantation (baseline left ventricular ejection fraction [LVEF] 27 ± 6%, baseline QRS duration 149 ± 33 ms, age = 63 ± 11 years). CP associated with CRT (CRT + CP) was delivered during CRT-D implantation from the right and left ventricular leads simultaneously. Echocardiography data were collected at baseline, during CRT and CRT + CP to assess changes in LVEF, cardiac output (CO), longitudinal global strain assessed by speckle tracking, and LV dyssynchrony (opposing wall delay using tissue Doppler imaging). Compared to the conventional CRT, heart rate (HR) markedly decreased during CRT + CP (79 ± 20 beats/min vs 51 ± 8 beats/min, P < 0.0001) and was associated with a significant increase in LVEF (30 ± 8% vs 35 ± 8%, P = 0.0002) and peak of longitudinal global strain (-6 ± 2% vs -8 ± 2%, P < 0.0001). Importantly, during CRT + CP, CO increased (3.8 ± 1.0 L/min vs 4.4 ± 1.4 L/min, P = 0.004) and cardiac synchronicity remained unchanged (38 ± 24 ms for CRT alone vs 27 ± 18 ms for CRT + CP, P = 0.1). In sinus rhythm HF patients, acute CP application in addition to CRT decreases HR and contributes to myocardial contractility and CO improvement without deleterious impact on ventricular synchronicity.

Outcome of pulmonary vein isolation ablation for paroxysmal atrial fibrillation: predictive role of left atrial mechanical dyssynchrony by speckle tracking echocardiography

Although few clinical variables have been associated with recurrence of atrial fibrillation (AF) after pulmonary vein isolation (PVI) the role of left atrial (LA) mechanical function in the outcome of catheter ablation of AF is not adequately defined. The aim of our study was to determine whether LA mechanical dyssynchrony as evaluated by speckle tracking echocardiography can predict outcome of PVI ablation procedure in patients with paroxysmal AF. Twenty-five patients (age 58 ± 11 years, [mean ± standard deviation], 17 males) with paroxysmal AF who met specific enrollment criteria pertaining to clinical presentation and follow-up, assessment of LA mechanical dyssynchrony, and strategy of catheter ablation procedure were enrolled. For LA mechanical dyssynchrony assessment, the time to peak longitudinal strain (TPk) in opposing walls in the midportion of the LA walls at peak atrial contraction in standard two- and four-chamber echocardiographic views by vector velocity imaging (VVI) was measured. Outcome of PVI procedure, whether no recurrence (NR) or AF recurrence (AFR) after 3 months of post-procedural blanking period, was evaluated based on AF-related symptoms and documentation of AF by electrocardiogram, continuous 24-h Holter, and intermittent event monitor recordings. During a follow-up period of 20.3 ± 8.6 months, 18 out of 25 (72 %) patients had no recurrence (NR group), and 7 out of 25 (28 %) patients had recurrence of AF (AFR group). Significant gender difference was observed in terms of outcome such that all AFR patients were men and no woman had recurrence of AF. Between the NR and AFR groups, neither the left atrial diameter, 4.0 ± 0.3 and 4.2 ± 0.2 cm, respectively (p = 0.2), nor the left atrial volume indexes, 45 ± 15 and 48 ± 20 ml/m(2), respectively (p = 0.56), were statistically significantly different. For LA mechanical function, compared to the patients in NR group who had maximum opposing wall TPk delay of 39.9 ± 12.0 ms, those in the AFR group demonstrated significantly more LA mechanical dyssynchrony with maximum opposing wall TPk delay of 64.4 ± 17.0 ms prior to ablation (p = 0.007). Using receiver operative characteristic analyses of the data that had an area under the curve of 0.865, we identified a maximum opposing wall delay cutoff value of 51 ms which predicted AF recurrence with sensitivity and specificity values of 89 and 72 %, respectively (p = 0.005). Speckle tracking strain analysis echocardiography can evaluate the LA mechanical dyssynchrony quantitatively. The severity of LA mechanical dyssynchrony by VVI can predict the outcome of PVI catheter ablation for paroxysmal AF.

Distribution of Dyssynchrony in Subjects with No Known Cardiac Disease and Comparison of Velocity Vector Imaging to Color‐Coded Tissue Doppler Imaging

Data on the distribution of dyssynchrony in subjects with normal ejection fraction (EF) and normal QRS are scarce. We studied 100 subjects with no known cardiac disease (52% male, mean age 60 ± 17 years) using velocity vector imaging (VVI). Seventeen percent had septal to lateral (S-L) wall longitudinal delay >75 msec, 63% of subjects had S-L wall radial delay >75 msec, and 25% had a circumferential opposing wall delay >100 msec. Those with circumferential opposing wall delay of >100 msec had a lower EF (57 ± 5% vs. 62 ± 5%, P < 0.05). In an additional group of 33 patients, we compared the longitudinal dyssynchrony parameters as assessed by VVI and tissue Doppler imaging (TDI) and found them to be comparable. In conclusion, we find significant variation in time to peak velocities in subjects with no known cardiac disease, who had a normal left ventricular ejection fraction and QRS duration. VVI is comparable to TDI.

Relationship between fragmented QRS and response to cardiac resynchronization therapy

Cardiac resynchronization therapy (CRT) is an effective treatment for heart failure (HF) with a wide QRS. Fragmented QRS (fQRS) on a 12-lead electrocardiography (ECG) has been shown to predict cardiac events in several patient populations. We aimed to investigate the relationship between fragmented wide QRS (f-wQRS) and left ventricular dyssynchrony and response to CRT. Fifty-three patients with HF undergoing CRT were studied. The presence of fQRS was assessed using standardized criteria. Dyssynchrony was defined as interventricular mechanical delay (IVMD) ≥40 ms and tissue Doppler velocity opposing-wall delay ≥65 ms. Echocardiographic response to CRT was defined by a ≥15 % reduction in left ventricular end-systolic volume at 6 months follow-up. Fragmented wide QRS was present in 17 (32 %) patients. Interventricular and intraventricular dyssynchrony were highly prevalent in both patient groups with f-wQRS and nonf-wQRS (64.7 % vs 75 %, p = 0.44; 70.6 % vs 72.2 %, p = 0.25). Ischemic HF was significantly higher in patients with f-wQRS than patients with nonf-wQRS (64 % vs 33 %, p = 0.03). Reverse remodeling was developed in 32 (89 %) and 6 (35 %) of patients with nonf-wQRS and f-wQRS, respectively (p = 0.001). In multivariate analysis, significant associates of response to CRT were evaluated adjusting for etiology of cardiomyopathy, QRS width, IVMD, intraventricular delay, and f-wQRS. Lack of f-wQRS was the only predictor of response to CRT (OR 1.556, 95 % CI, 0.016-0.806, p = 0.028). Presence of dyssynchrony is necessary but not sufficient to select appropriate candidates for CRT. Presence of f-wQRS on baseline ECG may play a role in identifying patients who may not respond to CRT.

Mechanical dyssynchrony evaluated by tissue Doppler cross-correlation analysis is associated with long-term survival in patients after cardiac resynchronization therapy

Pre-implant assessment of longitudinal mechanical dyssynchrony using cross-correlation analysis (XCA) was tested for association with long-term survival and compared with other tissue Doppler imaging (TDI)-derived indices. In 131 patients referred for cardiac resynchronization therapy (CRT) from two international centres, mechanical dyssynchrony was assessed from TDI velocity curves using time-to-peak opposing wall delay (OWD) ≥80 ms, Yu index ≥32 ms, and the maximal activation delay (AD-max) >35 ms. AD-max was calculated by XCA of the TDI-derived myocardial acceleration curves. Outcome was a composite of all-cause mortality, cardiac transplantation, or implantation of a ventricular assist device (left ventricular assist device) and modelled using the Cox proportional hazards regression. Follow-up was truncated at 1460 days. Dyssynchrony by AD-max was independently associated with improved survival when adjusted for QRS > 150 ms and aetiology {hazard ratio (HR) 0.35 [95% confidence interval (CI) 0.16-0.77], P = 0.01}. Maximal activation delay performed significantly better than Yu index, OWD, and the presence of left bundle branch block (P < 0.05, all, for difference between parameters). In subgroup analysis, patients without dyssynchrony and QRS between 120 and 150 ms showed a particularly poor survival [HR 4.3 (95% CI 1.46-12.59), P < 0.01, compared with the group with dyssynchrony and QRS between 120 and 150 ms]. Mechanical dyssynchrony assessed by AD-max was associated with long-term survival after CRT and was significantly better associated compared with other TDI-derived indices. Patients without dyssynchrony and QRS between 120 and 150 ms had a particularly poor prognosis. These results indicate a valuable role for XCA in selection of CRT candidates.

Intra‐ and Interobserver Reproducibility of Left Ventricular Mechanical Dyssynchrony Assessment by Real Time Three‐Dimensional Echocardiography

Real time three-dimensional (3D) echocardiography allows the assessment of left ventricular (LV) mechanical dyssynchrony and may be useful in predicting response to cardiac resynchronization therapy. However, reproducibility of 3D dyssynchrony in past reports varied widely. We evaluated intra- and interobserver reproducibility of parameters of LV mechanical dyssynchrony by 3D echocardiography and explored the impact of image quality as a possible source of variability. LV volumes and ejection fraction (LV EF) were measured by 3D echocardiography in 90 subjects. LV mechanical dyssynchrony was calculated as the standard deviation of the time-to-minimum segmental volume (Tmsv) over 16 (SDI16) and 12 (SDI12) segments and as the maximum time-difference in Tmsv over 16 (Dif16), 12 (Dif12), and 2 (DifS-L) segments. Opposing wall delay in peak myocardial systolic velocity (S-L delay) by tissue Doppler imaging (TDI) was also evaluated. Feasibility of 3D measurements was 88.9%. Intra- and interobserver intraclass correlation coefficients were excellent for LV volumes, LV EF, and S-L delay (all ≥ 0.90), very good for SDI16 (0.83 and 0.85), moderate to good for SDI12, Dif16, Dif12, and DifS-L (0.51-0.81). No systematic bias was present between readings for 3D dyssynchrony, but limits of agreement resulted fairly large for most parameters with the exception of SDI16, which showed reproducibility slightly lower than TDI. Suboptimal image quality was a significant source of variability in 3D-dyssynchrony assessment. The 3D assessment of LV volumes and dyssynchrony was feasible in our community-based cohort. SDI16 was the most reproducible among 3D-dyssynchrony parameters and the least affected by image quality.

Abstract 9973: Mitral Regurgitation with Mechanical Dyssynchrony as a Substrate Associated with Long-Term Survival After Cardiac Resynchronization Therapy

Background: Mechanisms for mitral regurgitation (MR) in patients with left ventricular (LV) dysfunction are complex. Cardiac resynchronization therapy (CRT) may improve MR. However, effects are variable and the influence of mechanical dyssynchrony on MR and its association with long-term outcome is unclear. Methods: We prospectively studied 138 consecutive CRT patients with NYHA class III/IV heart failure, QRS width ≥120ms, and ejection fraction (EF) ≤35%. Quantitative echocardiography was performed before CRT and 1.5±2 months after CRT. Baseline dyssynchrony was assessed as interventricular mechanical delay (IVMD) &gt; 40ms, tissue Doppler opposing wall delay (OWD) &gt; 65ms, Yu Index &gt; 32ms, and speckle tracking radial strain delay &gt;130ms. MR was quantified by vena contracta width and jet area, and severity expressed as a grade from 1 to 4. Long-term outcome events were pre-specified as death, transplant or left ventricular assist device over 4 years. Results: Of 138 CRT patients aged 66±12 yrs with EF 24±7%, 74 patients (54%) had no significant baseline MR (≤grade 1+), and 64 patients (46%) had significant baseline MR: n=35 grade 2+, n=20 grade 3+, and n=9 grade 4+. At baseline, There are significant differences in EF (p&lt;0.01) and MR severity (&lt;0.0001) between patients with and without significant MR. Dyssynchrony at baseline by all indices were statistically associated with MR reduction (all p&lt;0.03). Among patients with significant MR at baseline, speckle-tracking radial dyssynchrony was significantly associated with long-term event free survival. Conclusion: The co-existence of baseline dyssynchrony by radial strain in patients with significant MR was associated with a more favorable long term survival after CRT. Patients with significant MR who lacked dyssynchrony had the least favorable outcome. These observations have mechanistic and clinical implications.

Left Ventricular Mechanical Dyssynchrony in Acute Onset Cardiomyopathy: Association of Its Resolution With Improvements in Ventricular Function

The purpose of this study was to evaluate mechanical dyssynchrony in patients with acute onset cardiomyopathy with narrow QRS interval, and its association with improvements in left ventricular (LV) function. LV dyssynchrony has been usually studied in patients with chronic heart failure and wide QRS in the context of cardiac resynchronization therapy. We studied 201 patients enrolled in the IMAC-2 (Inflammatory Mediators in Acute Cardiomyopathy) trial with recent onset nonischemic cardiomyopathy and ejection fraction <40%. Dyssynchrony was assessed using speckle-tracking velocity vector imaging. Diastolic function was assessed by mitral inflow E and mitral E' annular velocities (E/E'). A normal control group of 15 normal volunteers was studied for comparison. Although mean QRS was narrow (98 ± 21 ms), 108 (54%) acute cardiomyopathy patients had significant LV dyssynchrony at presentation: opposing wall delay 89 ± 51 ms, versus 35 ± 11 ms in controls, and 12-site standard deviation 43 ± 23, versus 24 ± 8 ms in controls (p < 0.001). Patients with dyssynchrony had greater degrees of diastolic dysfunction: E/E' 15 ± 8 versus 12 ± 6 (p < 0.05). At 6 months, group mean ejection fraction improved from 23 ± 8% to 40 ± 12% and E/E' improved from 14 ± 7 to 9 ± 5 (both p < 0.001). Dyssynchrony improved from 89 ± 51 ms to 52 ± 35 ms in maximum opposing wall delay, and 43 ± 23 ms to 32 ± 19 ms in 12-site standard deviation, and the prevalence of dyssynchrony decreased to 12% after 6 months (p < 0.001 vs. baseline). Mechanical dyssynchrony was observed in a significant number of patients with acute onset cardiomyopathy, despite having a narrow QRS interval. Resolution of dyssynchrony associated with improvements in LV function occurred in the large majority of these patients.

A practical approach to imaging dyssynchrony for cardiac resynchronization therapy

Cardiac resynchronization therapy (CRT) is believed to benefit patients by primarily correcting heterogeneity in regional ventricular mechanical contraction, known as dyssynchrony. Although many symptomatic heart failure patients with depressed left ventricular ejection fraction and widened electrocardiographic QRS complexes have clinical improvement from CRT, a significant subset of approximately one-third do not seem to respond. Because the degree of mechanical dyssynchrony may be widely variable, interest has remained high to attempt to improve patient selection for CRT using cardiac imaging as a means to quantify dyssynchrony. This article will review the principal echocardiographic methods of dyssynchrony analysis by tissue Doppler imaging, (opposing wall delay, 12-site standard deviation or Yu index, and longitudinal strain), routine pulsed-Doppler (interventricular mechanical delay, pre-ejection delay and filling time ratio), and speckle tracking (including radial, circumferential, and longitudinal strain). In addition, dyssynchrony analysis by cardiac magnetic resonance imaging is introduced as a potential alternative technique. The technical features, strengths and limitations, and clinical evidence for these methods are discussed, including a practical clinical approach.

Association of intraventricular mechanical dyssynchrony with response to cardiac resynchronization therapy in heart failure patients with a narrow QRS complex

AimsCurrent criteria for cardiac resynchronization therapy (CRT) are restricted to patients with a wide QRS complex (>120 ms). Overall, only 30% of heart failure patients demonstrate a wide QRS complex, leaving the majority of heart failure patients without this treatment option. However, patients with a narrow QRS complex exhibit left ventricular (LV) mechanical dyssynchrony, as assessed with echocardiography. To further elucidate the possible beneficial effect of CRT in heart failure patients with a narrow QRS complex, this two-centre, non-randomized observational study focused on different echocardiographic parameters of LV mechanical dyssynchrony reflecting atrioventricular, interventricular and intraventricular dyssynchrony, and the response to CRT in these patients.Methods and resultsA total of 123 consecutive heart failure patients with a narrow QRS complex (<120 ms) undergoing CRT was included at two centres. Several widely accepted measures of mechanical dyssynchrony were evaluated: LV filling ratio (LVFT/RR), LV pre-ejection time (LPEI), interventricular mechanical dyssynchrony (IVMD), opposing wall delay (OWD), and anteroseptal posterior wall delay with speckle tracking (ASPWD). Response to CRT was defined as a reduction ≥15% in left ventricular end-systolic volume at 6 months follow-up. Measures of dyssynchrony can frequently be observed in patients with a narrow QRS complex. Nonetheless, for LVFT/RR, LPEI, and IVMD, presence of predefined significant dyssynchrony is <20%. Significant intraventricular dyssynchrony is more widely observed in these patients. With receiver operator characteristic curve analyses, both OWD and ASPWD demonstrated usefulness in predicting response to CRT in narrow QRS patients with a cut-off value of 75 and 107 ms, respectively.ConclusionMechanical dyssynchrony can be widely observed in heart failure patients with a narrow QRS complex. In particular, intraventricular measures of mechanical dyssynchrony may be useful in predicting LV reverse remodelling at 6 months follow-up in heart failure patients with a narrow QRS complex, but with more stringent cut-off values than currently used in ‘wide’ QRS patients.

Dyssynchrony by speckle-tracking echocardiography and response to cardiac resynchronization therapy: results of the Speckle Tracking and Resynchronization (STAR) study

AimsThe Speckle Tracking and Resynchronization (STAR) study used a prospective multi-centre design to test the hypothesis that speckle-tracking echocardiography can predict response to cardiac resynchronization therapy (CRT).Methods and resultsWe studied 132 consecutive CRT patients with class III and IV heart failure, ejection fraction (EF) ≤35%, and QRS ≥120 ms from three international centres. Baseline dyssynchrony was evaluated by four speckle tracking strain methods; radial, circumferential, transverse, and longitudinal (≥130 ms opposing wall delay for each). Pre-specified outcome variables were EF response and three serious long-term events: death, transplant, or left ventricular assist device. Of 120 patients (91%) with baseline dyssynchrony data, both short-axis radial strain and transverse strain from apical views were associated with favourable EF response 7 ± 4 months and long-term outcome over 3.5 years (P < 0.01). Radial strain had the highest sensitivity at 86% for predicting EF response with a specificity of 67%. Serious long-term unfavourable events occurred in 20 patients after CRT, and happened three times more frequently in those who lacked baseline radial or transverse dyssynchrony than in patients with dyssynchrony (P < 0.01). Patients who lacked both radial and transverse dyssynchrony had unfavourable clinical events occur in 53%, in contrast to events occurring in 12% if baseline dyssynchrony was present (P < 0.01). Circumferential and longitudinal strains predicted response when dyssynchrony was detected, but failed to identify dyssynchrony in one-third of patients who responded to CRT.ConclusionDyssynchrony by speckle-tracking echocardiography using radial and transverse strains is associated with EF response and long-term outcome following CRT.