Effects of left bundle branch block on echocardiographic coronary flow assessment: A systematic review.

This systematic review investigates the diagnostic and prognostic utility of coronary flow reserve (CFR) assessment through echocardiography in patients with left bundle branch block (LBBB), a condition known to complicate the clinical evaluation of coronary artery disease (CAD). The literature search was performed on PubMed, EMBASE, Web of Science, Scopus, and Google Scholar, was guided by PRISMA standards up to March 2024, and yielded six observational studies that met inclusion criteria. These studies involved a diverse population of patients with LBBB, employing echocardiographic protocols to clarify the impact of LBBB on coronary flow dynamics. The findings emphasize the importance of CFR in stratifying cardiovascular risk and guiding clinical decision-making in patients with LBBB. Pooled results reveal that patients with LBBB and significant left anterior descending (LAD) artery stenosis exhibited a marked decrease in stress-peak diastolic velocity (MD = -19.03 [-23.58; -14.48] cm/s; p < .0001) and CFR (MD = -.60 [-.71; -.50]; p < .0001), compared to those without significant LAD lesions, suggesting the efficacy of stress echocardiography CFR assessment in the identification of clinically significant CAD among the LBBB population. This review highlights the clinical relevance of echocardiography CFR assessment as a noninvasive tool for evaluating CAD and stratifying risk in the presence of LBBB and underscores the need for standardized protocols in CFR measurement.

Assessment of myocardial strain patterns in patients with left bundle branch block using cardiac magnetic resonance.

Recently, a classification with four types of septal longitudinal strain patterns was described using echocardiography, suggesting a pathophysiological continuum of left bundle branch block (LBBB)-induced left ventricle (LV) remodeling. The aim of this study was to assess the feasibility of classifying these strain patterns using cardiovascular magnetic resonance (CMR), and to evaluate their association with LV remodeling and myocardial scar. Single center registry included LBBB patients with septal flash (SF) referred to CMR to assess the cause of LV systolic dysfunction. Semi-automated feature-tracking cardiac resonance (FT-CMR) was used to quantify myocardial strain and detect the four strain patterns. A total of 115 patients were studied (age 66 ± 11 years, 57% men, 28% with ischemic heart disease). In longitudinal strain analysis, 23 patients (20%) were classified in stage LBBB-1, 37 (32.1%) in LBBB-2, 25 (21.7%) in LBBB-3, and 30 (26%) in LBBB-4. Patients at higher stages had more prominent septal flash, higher LV volumes, lower LV ejection fraction, and lower absolute strain values (p < 0.05 for all). Late gadolinium enhancement (LGE) was found in 55% of the patients (n = 63). No differences were found between the strain patterns regarding the presence, distribution or location of LGE. Among patients with LBBB, there was a good association between strain patterns assessed by FT-CMR analysis and the degree of LV remodeling and LV dysfunction. This association seems to be independent from the presence and distribution of LGE.

Seismocardiography as a tool for assessment of bi-ventricular pacing.

Objective.Conduction-induced heart failure in patients with left bundle branch block (LBBB) can benefit from cardiac resynchronization therapy (CRT). However, some patients are non-responders to the therapy with one contributing factor being poor optimization of the atrioventricular (AV) pacing delay. In this study, we have investigated the pacing-induced changes in the seismocardiogram (SCG).Approach.14 patients with heart failure, LBBB, and CRT were included. SCG was recorded with pacing turned on and off. Based on a mean SCG heartbeat from each patient, fiducial points were annotated, and cardiac timing intervals (CTI) and amplitudes were derived. These were compared between the CRT group and a group of healthy normal subjects (n= 14). Echocardiography was also used to derive CTI. Intervals derived from the SCG and echocardiogram were correlated.Main results.The isovolumetric contraction time (IVCT) derived from SCG was significantly shorter in the CRT group when the pacemaker was turned on (63.2-52.6 ms,p= 0.027). The first peak-to-peak amplitude in the systolic complex was significantly larger with the pacemaker turned on (p= 0.002), as well as the ∣max-min∣ amplitude in the systolic complex (p= 0.003). Isovolumetric relaxation time and left ventricular ejection time (LVET) were not significantly different between pacemaker settings. Compared to normal subjects, IVCT was significantly prolonged with the pacemaker turned off. All amplitudes were significantly larger in the healthy subject group. IVCT and LVET derived from SCG were significantly correlated to the echocardiogram.Significance.IVCT shortened and SCG amplitudes increased in response to CRT, indicating a more efficient ventricular contraction. This demonstrates the possibility to detect cardio-mechanic changes in response to treatment with the SCG. However, for the patients the systolic part of the SCG was abnormal and difficult to characterize, raising concerns about the correct interpretation of the SCG.

Epicardial fat thickness assessment by multi-slice computed tomography for predicting cardiac outcomes in patients undergoing transcatheter aortic valve implantation.

INTRODUCTION: Chronic inflammation promotes aortic valve calcification. It is known that epicardial fat is a source of inflammation. The aim of this study was to investigate the relationship between epicardial fat thickness, cardiac conduction disorders and outcomes in patients undergoing transcatheter aortic valve implantation (TAVI). METHODS: During a three-year period, 45 patients with severe aortic stenosis who underwent TAVI were recruited to the study. Data were collected retrospectively. Epicardial fat was defined as the adipose tissue between the epicardium and the visceral pericardium. Mean epicardial fat thickness was determined by multi-slice computed tomography, which was performed before the procedure. RESULTS: The average thickness of epicardial fat was 13.06 ± 3.29 mm. This study failed to reveal a significant correlation between epicardial fat thickness and post-procedural left bundle branch block, right bundle branch block, paravalvular aortic regurgitation and pacemaker implantation rates (p > 0.05). CONCLUSIONS: The results of this study failed to show a significant relationship between epicardial fat thickness, cardiac conduction disorders and outcomes, however further studies with larger sample numbers are required to explore the relationship.

Effect of isolated left bundle-branch block on biventricular volumes and ejection fraction: a cardiovascular magnetic resonance assessment.

BACKGROUND: Left bundle branch block (LBBB) is associated with abnormal left ventricular (LV) contraction, and is frequently associated with co-morbid cardiovascular disease, but the effect of an isolated (i.e. in the absence of cardiovascular dissease) LBBB on biventricular volumes and ejection fraction (EF) is not well characterized. The objective of this study was to compare LV and right ventricular (RV) volumes and EF in adults with an isolated LBBB to matched healthy controls and to population-derived normative values, using cardiovascular magnetic resonance (CMR) imaging. METHODS: We reviewed our clinical echocardiography database and the Framingham Heart Study Offspring cohort CMR database to identify adults with an isolated LBBB. Age-, sex-, hypertension-status, and body-surface area (BSA)-matched controls were identified from the Offspring cohort. All study subjects were scanned using the same CMR hardware and imaging sequence. Isolated-LBBB cases were compared with matched controls using Wilcoxon paired signed-rank test, and to normative reference values via Z-score. RESULTS: Isolated-LBBB subjects (n = 18, 10F) ranged in age from 37 to 82 years. An isolated LBBB was associated with larger LV end-diastolic and end-systolic volumes (both p < 0.01) and lower LVEF (56+/- 7% vs. 68+/- 6%; p <0.001) with similar myocardial contraction fraction. LVEF in isolated LBBB was nearly two standard deviations (Z = - 1.95) below mean sex and age-matched group values. LV stroke volume, cardiac output, and mass, and all RV parameters were similar (p = NS) between the groups. CONCLUSIONS: Adults with an isolated LBBB have greater LV volumes and markedly reduced LVEF, despite the absence of overt cardiovascular disease. These data may be useful toward the clinical interpretation of imaging studies performed on patients with an isolated LBBB.

Exercise-induced left bundle branch block - A case report with stress-echocardiographic assessment.

We report the case of a 51-year-old male who presented with exertional chest discomfort and dyspnea concurring with an exercise-induced left bundle branch block (EI-LBBB). Possible underlying causes and treatment options are presented and discussed. The case represents the first stress-echocardiographic assessment of a case with EI-LBBB, performed in order to document a possible left ventricular dyssynchrony during the EI-LBBB and thereby the possible treatment option of biventricular pacemaker implantation.

Evaluation of the ECG based Selvester scoring method to estimate myocardial scar burden and predict clinical outcome in patients with left bundle branch block, with comparison to late gadolinium enhancement CMR imaging.

BACKGROUND: Myocardial scar burden quantification is an emerging clinical parameter for risk stratification of sudden cardiac death and prediction of ventricular arrhythmias in patients with left ventricular dysfunction. We investigated the relationships among semiautomated Selvester score burden and late gadolinium enhancement-cardiovascular magnetic resonance (LGE-CMR) assessed scar burden and clinical outcome in patients with underlying heart failure, left bundle branch block (LBBB) and implantable cardioverter-defibrillator (ICD) treatment. METHODS: Selvester QRS scoring was performed on all subjects with ischemic and nonischemic dilated cardiomyopathy at Skåne University Hospital Lund (2002-2013) who had undergone LGE-CMR and 12-lead ECG with strict LBBB pre-ICD implantation. RESULTS: Sixty patients were included; 57% nonischemic dilated cardiomyopathy and 43% ischemic cardiomyopathy with mean left ventricular ejection fraction of 27.6% ± 11.7. All patients had scar by Selvester scoring. Sixty-two percent had scar by LGE-CMR (n = 37). The Spearman correlation coefficient for LGE-CMR and Selvester score derived scar was r = .35 (p = .007). In scar negative LGE-CMR, there was evidence of scar by Selvester scoring in all patients (range 3%-33%, median 15%). Fourteen patients (23%) had an event during the follow-up period; 11 (18%) deaths and six adequate therapies (10%). There was a moderate trend indicating that presence of scar increased the risk of clinical endpoints in the LGE-CMR analysis (p = .045). CONCLUSION: There is a modest correlation between LGE-CMR and Selvester scoring verified myocardial scar. CMR based scar burden is correlated to clinical outcome, but Selvester scoring is not. The Selvester scoring algorithm needs to be further refined in order to be clinically relevant and reliable for detailed scar evaluation in patients with LBBB.

The Impact of Infarct Location and Extent on LV Motion Patterns: Implications for Dyssynchrony Assessment.

OBJECTIVES: This study sought to investigate the influence of scar extent and location on the motion pattern of the left ventricle (LV) and its interaction with LV conduction delays. BACKGROUND: Different echocardiographic parameters have been proposed to identify responders to cardiac resynchronization therapy based on the detection of LV mechanical dyssynchrony. However, the impact of infarct scar on the diagnostic performance of these parameters remains unknown. METHODS: We included 11 healthy volunteers and 122 patients with normal and severely reduced function, wide and narrow QRS, as well as with and without infarct scar. Location and extent of infarct scar was defined by contrast-enhanced cardiac magnetic resonance. Influence of infarct scar on the motion pattern of the LV was examined by measuring direction and amplitude of apical rocking. The influence of scar on different echocardiographic dyssynchrony parameters was investigated. RESULTS: Scar in the absence of conduction delay caused most apical rocking in the presence of 3 to 4 infarct segments. Pure apical infarction caused no rocking. In wide QRS patients without infarct scar, apical rocking was mainly dominated by the conduction delay, whereas in wide QRS patients with ischemic cardiomyopathy, this pattern was modulated by the scar. Apical rocking was inversely related to scar extent (r = -0.54, p < 0.05). Apical rocking was better associated with cardiac resynchronization therapy response than conventional dyssynchrony measurements. CONCLUSIONS: LV motion patterns are mainly dominated by conduction delays, but they are also modulated by infarct scar. Higher scar burden resulted in less pronounced apical rocking. Apical rocking is more strongly associated with cardiac resynchronization therapy response than with conventional echocardiographic parameters and may therefore be used as a screening parameter.

Assessment of left ventricular mechanical dyssynchrony in left bundle branch block canine model: Comparison between cine and tagged MRI.

PURPOSE: To compare cine and tagged magnetic resonance imaging (MRI) for left ventricular dyssynchrony assessment in left bundle branch block (LBBB), using the time-to-peak contraction timing, and a novel approach based on cross-correlation. MATERIALS AND METHODS: We evaluated a canine model dataset (n = 10) before (pre-LBBB) and after induction of isolated LBBB (post-LBBB). Multislice short-axis tagged and cine MRI images were acquired using a 1.5 T scanner. We computed contraction time maps by cross-correlation, based on the timing of radial wall motion and of circumferential strain. Finally, we estimated dyssynchrony as the standard deviation of the contraction time over the different regions of the myocardium. RESULTS: Induction of LBBB resulted in a significant increase in dyssynchrony (cine: 13.0 ± 3.9 msec for pre-LBBB, and 26.4 ± 5.0 msec for post-LBBB, P = 0.005; tagged: 17.1 ± 5.0 msec at for pre-LBBB, and 27.9 ± 9.8 msec for post-LBBB, P = 0.007). Dyssynchrony assessed by cine and tagged MRI were in agreement (r = 0.73, P = 0.0003); differences were in the order of time difference between successive frames of 20 msec (bias: -2.9 msec; limit of agreement: 10.1 msec). Contraction time maps were derived; agreement was found in the contraction patterns derived from cine and tagged MRI (mean difference in contraction time per segment: 3.6 ± 13.7 msec). CONCLUSION: This study shows that the proposed method is able to quantify dyssynchrony after induced LBBB in an animal model. Cine-assessed dyssynchrony agreed with tagged-derived dyssynchrony, in terms of magnitude and spatial direction. J. MAGN. RESON. IMAGING 2016;44:956-963.

Myocardial blood flow assessment with 82rubidium-PET imaging in patients with left bundle branch block.

OBJECTIVES: Perfusion abnormalities are frequently seen in Single Photon Emission Computed Tomography (SPECT) when a left bundle branch block is present. A few studies have shown decreased coronary flow reserve in the left anterior descending territory, regardless of the presence of coronary artery disease. OBJECTIVE: We sought to investigate rubidium-82 (82Rb) positron emission tomography imaging in the assessment of myocardial blood flow and coronary flow reserve in patients with left bundle branch block. METHODS: Thirty-eight patients with left bundle branch block (GI), median age 63.5 years, 22 (58%) female, 12 with coronary artery disease (≥70%; GI-A) and 26 with no evidence of significant coronary artery disease (GI-B), underwent rest-dipyridamole stress 82Rb-positron emission tomography with absolute quantitative flow measurements using Cedars-Sinai software (mL/min/g). The relative myocardial perfusion and left ventricular ejection fraction were assessed in 17 segments. These parameters were compared with those obtained from 30 patients with normal 82Rb-positron emission tomography studies and without left bundle branch block (GII). RESULTS: Stress myocardial blood flow and coronary flow reserve were significantly lower in GI than in GII (p<0.05). The comparison of coronary flow reserve between GI-A and GI-B showed that it was different from the global coronary flow reserve (p<0.05) and the stress flow was significantly lower in the anterior than in the septal wall for both groups. Perfusion abnormalities were more prevalent in GI-A (p=0.06) and the left ventricular ejection fraction was not different between GI-A and GI-B, whereas it was lower in GI than in GII (p<0.001). CONCLUSION: The data confirm that patients with left bundle branch block had decreased myocardial blood flow and coronary flow reserve and coronary flow reserve assessed by 82Rb-positron emission tomography imaging may be useful in identifying coronary artery disease in patients with left bundle branch block.

Assessment of mechanical dyssynchrony in cardiac resynchronization therapy.

BACKGROUND: Cardiac resynchronization therapy (CRT) significantly reduces morbidity and mortality in patients with symptomatic severe heart failure and evidence of interventricular conduction delay by ECG. Unfortunately, one third of patients do not respond to CRT and selection criteria may need to be improved. Assessment of mechanical dyssynchrony by echocardiography has been suggested to add value in selection of CRT candidates. However, current methods for dyssynchrony analysis may not accurately reflect an activation delay amenable to CRT and controversy remains for the role of mechanical dyssynchrony. HYPOTHESIS: This thesis was based on the assumption that benefit from treatment with CRT requires a significant activation delay of the left ventricle (LV). It was hypothesized that echocardiographic methods for evaluation of mechanical dyssynchrony, reflecting this fundamental pathophysiologic change, could predict response to CRT. In addition, it was hypothesized that this approach would provide improved diagnostic value with regards to dyssynchrony analysis compared to conventional time-to-peak measurements. METHODS: Three studies were performed and consisted of: 1) A prospective study in 67 consecutive patients who fulfilled standard criteria for CRT and had left bundle branch block (LBBB) by ECG. Patients underwent 2D-strain echocardiography (speckle tracking analysis) one day prior to CRT, at day one and six months after implantation and the mechanics behind CRT-response was studied. Strain patterns thought to reflect a complete LBBB were characterized and the predictive ability of this approach was tested with regards to echocardiographic response at six months (> 15% reduction in LVESV) and compared to current time-to-peak indices. 2) A retrospective study in 131 consecutive patients from two centers. Patients all had a Tissue Doppler Imaging (TDI)-dyssynchrony study prior to implantation. Baseline mechanical dyssynchrony was determined by cross-correlation analysis (XCA), a more quantitative method for comparison of contraction patterns, and the association with long-term outcome (survival free from LVAD or heart transplantation after four years) was determined and compared to current time-to-peak indices. In addition, subgroup analysis of the relation to QRS-duration was performed. 3) A prospective study of 33 consecutive CRT-recipients. Patients were VV-optimized at day one after implantation. At six months, TDI and 2D-strain analysis were performed at six different interventricular pacing intervals in steps of 20 ms to investigate the performance of different indices of mechanical dyssynchrony (time-to-peak indices and XCA, respectively) and the relation between mechanical dyssynchrony and hemodynamic performance by LVOT VTI. RESULTS: 1) An LBBB-related strain pattern was highly predictive of LV re-modeling response to CRT at six months and significantly added to other known predictors of outcome (etiology and QRS > 150 ms). A reversal in strain-ratio between the early and late-activated myocardial regions was observed at day 1 only among responders suggestive of an important role in promotion of remodeling. 2) Mechanical dyssynchrony at baseline measured by XCA was independently associated with improved long-term outcome in CRT-recipients. Patients with lack of mechanical dyssynchrony and QRS between 120-150 ms showed particularly poor outcome. 3) VV-optimization after six months of CRT was beneficial in both responders and non-responders. Improvements in mechanical synchrony by any method translated into improved hemodynamics. XCA showed the best feasibility, reproducibility and correlation to hemodynamic performance. In all three studies, new methods for dyssynchrony assessment performed better compared to conventional indices. CONCLUSIONS: This thesis confirms the importance of mechanical dyssynchrony for outcome to CRT and demonstrates the value of dyssynchrony assessment for prediction of response to CRT as well as in optimization of device programming. New methods, which better reflect a significant LV activation delay, provides an improved tool for dyssynchrony analysis compared to conventional techniques.

Correlation of echocardiographic left atrial abnormality with myocardial ischemia during myocardial perfusion assessment in patients with left bundle branch block.

Left atrial (LA) abnormality, an easily quantifiable parameter of left ventricular (LV) diastolic dysfunction, has been associated with cardiovascular risk. Because during myocardial perfusion study (MPS), the abnormal LV activation pattern in patients with left bundle branch block (LBBB) frequently induces perfusion defects, a clinical correlate of early myocardial ischemia such as LA enlargement could alleviate some of these inherent challenges. We prospectively studied 144 consecutive patients with LBBB who underwent MPS after screening for electrocardiographic and echocardiographic LA enlargement over a 6-month period. Of those, 114 had a positive MPS result. We found that LA size (p <0.0001) and P-wave duration (p = 0.001) were significantly increased in patients as the severity of the defects increased on MPS, whereas LV ejection fraction was decrementally reduced (p = 0.001). Importantly, LA size (≥43.5 mm; sensitivity 70%, specificity 89%) and P-wave duration (≥135 milliseconds; sensitivity 63%, specificity 90%) were greatest when the MPS defect was severe. In conclusion, the presence of LA enlargement appears significantly correlated with myocardial ischemia among patients with LBBB and could therefore assist during MPS interpretation among patients in whom MPS interpretation could be challenging.

Risk stratification and prognostic assessment by myocardial perfusion-gated SPECT in patients with left bundle-branch block and low-intermediate cardiac risk.

OBJECTIVE: In high-risk patients with left bundle-branch block (LBBB), functional but not perfusion parameters yield incremental prognostic information. The aim of our study was to evaluate the prognostic value of gated single photon emission computed tomography (SPECT) in low-intermediate risk LBBB patients. METHODS: One hundred seventy-six subjects underwent stress-rest dual-day protocol 99mTc sestamibi-gated SPECT and were dichotomized in two groups: without LBBB (Group 1, n = 86) and with LBBB (Group 2, n = 90). Patients were followed for 32 ± 18 months. Cox regression multivariate analysis was used to determine which variable was the best predictor of cardiac event. Event-free survival curves were computed by Kaplan-Meier method. RESULTS: Myocardial perfusion scintigraphy was abnormal in 32 and 60 patients for Groups 1 and 2, respectively (37 vs. 67 %, p < 0.001). In Groups 1 and 2, the mean summed stress score (SSS) was 3.7 ± 5.6 versus 6.7 ± 6.4, while the mean summed difference score (SDS) was 1.6 ± 2.5 versus 2.7 ± 3.3 (both p < 0.005); therefore 34 % of patients in Group 1 and 53 % of those in Group 2 presented myocardial ischemia. All functional parameters were significantly different between the two subsets (all p < 0.005). Follow-up was completed in 161 patients (92 %); 10 events occurred in Group 1 and 20 in Group 2 (14 vs. 25 %). The event-free survival was significantly higher in patients with normal than in those with abnormal scan (85 vs. 63 %, p < 0.005); moreover, the prognosis of patients with LBBB was significantly worse. At multivariate analysis, SDS was found to be the only independent predictor of cardiac events both in all patients and in LBBB population (HR 3.08, and HR 4.99, p < 0.05). CONCLUSIONS: This is the first study to assess the prognostic value of gated SPECT in patients with LBBB and low-intermediate cardiac risk. Both perfusion and functional data obtained by gated SPECT are different between patients with and without LBBB. However, SDS is the only predictor of events. Thus, the amount of reversible ischemia at gated SPECT has a discriminative power in stratifying the cardiac risk of LBBB population.

Assessment of left ventricular dyssynchrony in pacing-induced left bundle branch block compared with intrinsic left bundle branch block.

AIMS: Although electrocardiographic and echocardiographic findings with right ventricular (RV) pacing mimic intrinsic left bundle branch block (LBBB), left ventricular (LV) mechanical activation pattern may differ. We compared mechanical activation pattern of the LV in RV-pacing-induced LBBB with intrinsic LBBB in symptomatic chronic heart failure patients. METHODS AND RESULTS: We studied 37 patients with chronic RV-pacing and 37 patients with intrinsic LBBB who were referred for cardiac resynchronization therapy. Echocardiographic study including 2D speckle tracking longitudinal strain and M-mode were performed at baseline. Patients with intrinsic LBBB were younger, had higher prevalence of ischaemic heart disease, and had more severe depressed LV function. The basal-septal segments were the earliest activated sites in 11% of patients in RV-pacing-induced LBBB compared with 30% in intrinsic LBBB (P= 0.04). The mid- and basal-lateral segments were the latest activated sites in 57% of patients in RV-pacing-induced LBBB compared with 30% in intrinsic LBBB (P = 0.03). Left ventricular dyssynchrony, using longitudinal strain, time delay ≥ 130 ms between either mid-septal or apico-septal and either basal or mid-lateral segments was present in 71% of patients with RV-pacing-induced LBBB compared with 59% in intrinsic LBBB (P = 0.03). Using M-mode, LV dyssynchrony was present in 11% of patients with RV-pacing-induced LBBB compared with 59% in intrinsic LBBB (P = 0.02). CONCLUSION: Right ventricular-pacing results in less early basal activation and more often early mid-septal and late lateral wall activation in comparison with intrinsic LBBB. Imaging techniques that only visualize the basal- or mid-part of the LV may result in a serious underestimation of dyssynchrony in patients with pacing-induced LBBB.

Quantitative assessment of strain and strain rate by velocity vector imaging during dobutamine stress echocardiography to predict outcome in patients with left bundle branch block.

BACKGROUND: Abnormal septal motion in left bundle branch block (LBBB) may compromise the interpretation of regional wall motion. Velocity vector imaging (VVI) has been proposed as an objective method to quantify regional myocardial deformation. The aim of this study was to determine whether VVI during dobutamine stress echocardiography (DSE) has prognostic value in patients with LBBB. METHODS: In 84 patients with (mean age, 75 +/- 9 years) undergoing DSE, longitudinal peak systolic strain (epsilon(sys)) and strain rate (SR(sys)) were measured in 16 segments using VVI. Results were expressed as average SR(sys) and epsilon(sys) per patient. Follow-up was obtained for the combined endpoint of mortality, myocardial infarction, and coronary revascularization. Contributions of clinical, conventional dobutamine stress echocardiographic, and epsilon(sys) and SR(sys) variables to outcome were assessed using Cox models. RESULTS: During a mean follow-up period of 18.3 +/- 13.8 months, 23 patients had endpoints. Wall motion score index at rest was the only independent predictor in a model combining clinical and conventional dobutamine stress echocardiographic variables. However, when epsilon(sys) and SR(sys) variables were considered, average SR(sys) at peak stress (hazard ratio, 2.38 per 0.2/s increment; 95% confidence interval, 1.53-3.88; P < .0001) became the only independent predictor of outcome. Using average SR(sys) at peak of -0.5/s as the cut point maximized the model chi(2) value for the prediction of outcomes (model chi(2) = 18.71, P = .002). The annualized event-free survival in patients with average SR(sys) at peak stress lower and higher than -0.5/s were 89.9% and 45.9%, respectively (P < .0001). CONCLUSION: Average SR(sys) at peak stress during DSE offers prognostic information incremental to wall motion analysis in patients with LBBB.

Real-time 3-dimensional echocardiographic assessment of left ventricular dyssynchrony: pitfalls in patients with dilated cardiomyopathy.

OBJECTIVES: This study sought to establish normal values for real-time 3-dimensional echocardiography (RT3DE)-derived left ventricular (LV) dyssynchrony index (LVDI) and determine its age dependency, and to compare dyssynchrony in patients with normal LV function and patients with dilated cardiomyopathy (DCM), with and without left bundle branch block (LBBB). BACKGROUND: Cardiac resynchronization therapy is known to be ineffective in one-third of patients with heart failure, highlighting the need for alternative techniques to assess LV dyssynchrony. METHODS: Datasets from RT3DE were analyzed to calculate LVDI using 16- and 17-segment models. First, 135 normal subjects were studied to establish LVDI abnormality threshold (mean + 2 SD) and to study the relationship with age. Then, 3 groups of patients (N = 16 each: DCM with and without LBBB, normal LV function with LBBB) were compared with 50 age-matched normal control subjects. RESULTS: In normal subjects, the 16-segment model resulted in a lower LVDI abnormality threshold than the 17-segment model (4.0% vs. 4.5%). In patients with normal LV function, LVDI was significantly lower than in those with DCM, irrespective of LBBB. Although LBBB resulted in a nearly 2-fold increase in LVDI in patients with normal LV function, its effects were nonsignificant in DCM. All patients with DCM and ejection fraction <35% had abnormally high LVDI, likely as a result of low signal-to-noise ratio in low-amplitude regional volume curves hampering accurate determination of regional ejection time. CONCLUSIONS: Normal values established in this study resulted in indiscriminate diagnosis of abnormal dyssynchrony in all patients with reduced LV function. The value of RT3DE-derived LVDI in the evaluation of dyssynchrony in patients with reduced LV function needs to be critically reassessed because of the inability to accurately detect end-ejection in low-amplitude regional volume curves. Alternative indices of dyssynchrony need to be developed to address this limitation.

Usefulness of baseline electrocardiographic QRS complex pattern to predict response to cardiac resynchronization.

Cardiac resynchronization therapy (CRT) improves morbidity and mortality in patients with heart failure with QRS>120 ms, yet most patients studied in clinical trials manifested baseline left branch bundle block (LBBB). It is unclear whether benefits of CRT extend to patients with right branch bundle block (RBBB) or a paced QRS at baseline despite QRS>120 ms. Orthotopic heart transplantation- and ventricular assist device-free survival, symptomatic response, and echocardiographic response were evaluated in the 636 patients who underwent CRT at our institution from 2000 to 2007 in whom the baseline electrocardiogram showed LBBB (n=412; 65%), paced QRS (n=162; 26%), or RBBB (n=62; 10%). Mortality was assessed using the Social Security Death Index, and the medical record was analyzed for clinical data. A decrease in New York Heart Association class>or=0.5 after >or=6 months of CRT defined symptomatic response. Echocardiographic evidence of improved left ventricular function and reverse remodeling was evaluated after >or=6 months of CRT. Survival free from orthotopic heart transplantation and ventricular assist device placement was best in patients with LBBB and worst in those with RBBB, whereas patients with paced QRS had an intermediate prognosis (p=0.003). This finding remained significant after controlling for baseline differences among the 3 groups. Symptomatic response was observed most often in patients with LBBB (60%), occurred least often in patients with RBBB (14%), and was intermediate in patients with paced QRS (46%; p<0.001). Echocardiographic improvement showed a similar stepwise trend. In conclusion, patients with RBBB undergoing CRT had low rates of symptomatic and echocardiographic response, and their survival free from orthotopic heart transplantation or ventricular assist device placement was significantly worse than in patients with LBBB. Patients with conventionally paced QRS experienced an intermediate response.

Velocity and deformation imaging for the assessment of myocardial dysfunction.

Recent developments in echocardiographic imaging technology and processing enabled the quantification of myocardial motion and deformation in a clinical setting. Echocardiographic strain (-rate) imaging provides a relatively easy way to study myocardial deformation. However, although (local) deformation is clearly linked to cardiac (dys-) function, it is important to understand how this information can be used in clinical practice and how specific deformation patterns should be interpreted. This review paper first discusses which issues are important to address when assessing cardiac function and how (regional) deformation and myocardial contractility are related. The use and interpretation of deformation profiles is further illustrated for some typical cardiac pathologies. The observed deformation patterns are discussed in light of the changes in regional contractility (ischemia), timing of contractile force development (LBBB and heart failure), pressure/volume overload, and assessing diastolic function.

Tissue Doppler Imaging in the assessment of selection and response from cardiac resynchronization therapy.

Mechanistic studies, observational evaluations, and randomized trials have consistently demonstrated the beneficial effects of cardiac resynchronization therapy (CRT) in patients with moderate-to-severe chronic systolic heart failure and ventricular dyssynchrony who have failed optimal medical treatment. However, despite the promising results, in some patients undergoing CRT, the symptoms of heart failure do not improve or even worse. One of the most important reasons for this failure is probably the lack of distinct mechanical dyssynchrony before implantation. This review discusses the actual and potential role of Tissue Doppler Imaging in selection of patients and optimisation of CRT.

Assessment of cardiac function and synchronicity in subjects with isolated bundle branch block using Doppler imaging.

BACKGROUND: Using tissue Doppler imaging and conventional echocardiographic technique, we examined the cardiac function and synchronicity in individuals with isolated right bundle branch block (RBBB) or left bundle branch block (LBBB) and assessed the relationship between QRS duration and synchronicity. METHODS: Subjects with isolated RBBB (n = 20), LBBB (n = 10) and normal controls (n = 20) were studied with conventional echocardiography and tissue Doppler imaging. The difference between aortic and pulmonary preejection intervals was defined as interventricular delay. Parameters in septum and lateral wall were measured using tissue Doppler imaging, including peak sustained systolic velocity (S(M)), peak early (E(M)) and late (A(M)) diastolic velocities as well as time to peak velocities (T(S), T(E) and T(A)). RESULTS: Subjects with LBBB had lower S(M) and longer T(S) than did the RBBB and control groups (P < 0.05, P < 0.001 respectively). A significant difference was observed in E(M), being the lowest in the LBBB and the highest in the control group (P < 0.05). Moreover, T(E) was longer in the LBBB group compared with the other two groups (P < 0.001). Both A(M) and T(A) were similar among three groups (P > 0.05). In the bundle branch block groups, one ventricle lagged about 40 ms behind the other. A significant correlation was found between interventricular delay and QRS duration (r = 0.713, P < 0.001). CONCLUSIONS: Cardiac ventricles were not well synchronized with one ventricle lagging about 40 ms behind the other in subjects with LBBB or RBBB, even though only LBBB group showed barely perceptible, impaired cardiac function. In addition, QRS duration and cardiac asynchronicity were positively correlated.