scholarly journals Sequential left ventricular electro-mechanical changes in presence of left bundle branch block

2021 ◽  
Vol 42 (Supplement_1) ◽  
Author(s):  
J Duchenne ◽  
S Calle ◽  
A Puvrez ◽  
F Rega ◽  
F Timmermans ◽  
...  
Keyword(s):  
Animal Model ◽  
Wall Thickness ◽  
Lateral Wall ◽  
Mechanical Dyssynchrony ◽  
Left Ventricular ◽  
Conduction Delay ◽  
Bundle Branch Block ◽  
Septal Wall ◽  
Qrs Duration ◽  
Over Time

Abstract Introduction Recent cross-sectional studies suggest a relationship between persisting left bundle branch block (LBBB) and the extent of left ventricular (LV) electro-mechanical alterations over time. When patients are referred for cardiac resynchronization therapy (CRT), temporal data during the sub-clinical phase of disease is often missing. A longitudinal study using an animal model would provide a better understanding of the relationship between the onset of LBBB and the electro-mechanical changes. Purpose To investigate the sequential alterations in LV structure and function that develop over time in an animal model of LBBB. Methods Thirteen sheep were subjected to rapid DDD pacing (180 bpm; leads on right atrium and right ventricular free wall) in order to induce a LBBB-like conduction delay. All animals underwent an 8-week pacing protocol, whereas 4 of them were subjected to 16 weeks of pacing in total. Echocardiographic speckle tracking was used to assess circumferential strain of the septal and lateral wall. Septal and lateral wall thickness were measured at end-diastole. Cardiac magnetic resonance imaging was used to determine LV volumes and ejection fraction (LVEF). Examinations took place at baseline (before and after start of pacing), and after 8 and 16 weeks of pacing. All examinations were performed at a physiologic heart rate of 110 bpm. Results At baseline, DDD pacing induced an increase in QRS duration (+85%, p<0.0001) and LBBB-like mechanical dyssynchrony, with mild early-systolic notching and preserved systolic shortening of the septal wall. The lateral wall demonstrated early pre-stretch followed by increasing systolic shortening. No acute changes in LV end-diastolic volume, LVEF or septal or lateral wall thickness were observed (all p>0.05). After 8 weeks of DDD pacing, mechanical dyssynchrony worsened: septal notching increased, followed by reduced systolic shortening. After 16 weeks, the initial septal shortening was followed by profound stretching throughout systole. Lateral wall systolic shortening was reduced compared to baseline. QRS duration increased further by +12% (week 8) and +20% (week 16) (all p<0.001). End-diastolic volumes had increased by +39% (week 8) and +72% (week 16), whereas LVEF had decreased by −48% (week 8) and −56% (week 16) (all p<0.001). Septal wall thickness had reduced by −24% (week 8) and −33% (week 16), while lateral wall thickness had increased by +21% (week 8) and +30% (week 16) (all p<0.05). Conclusion A persisting LBBB-like conduction delay induces sequential changes in LV deformation patterns, and triggers morphological and electrical remodelling. These changes are similar to those observed in patients with LBBB and different degrees of LV dysfunction. Our data suggest a continuum due to the progression of LBBB-induced LV disease. In the clinic, patients with mild dysfunction should be closely monitored in order to treat dyssynchrony as soon as guideline indications are reached. FUNDunding Acknowledgement Type of funding sources: Other. Main funding source(s): This work was supported by a KU Leuven research grant

scholarly journals Elevated septal wall stress - a driver of left ventricular dysfunction in left bundle branch block?

2021 ◽  
Vol 22 (Supplement_1) ◽  
Author(s):  
OJ Sletten ◽  
JM Aalen ◽  
EW Remme ◽  
H Izci ◽  
J Duchenne ◽  
...  
Keyword(s):  
Heart Failure ◽  
Wall Thickness ◽  
Left Bundle Branch Block ◽  
Wall Stress ◽  
Lateral Wall ◽  
Left Ventricular ◽  
Public Institution ◽  
Wall Thickening ◽  
Bundle Branch Block ◽  
Septal Wall

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): The Norwegian Health Association Background Septal dysfunction is a main feature of left bundle branch block (LBBB), and increasing wall stress is a proposed mechanism of heart failure development in LBBB patients. To try to reveal the pathophysiologic pathway from dyssynchrony to heart failure, we investigated the relationship between septal and left ventricular (LV) lateral wall stress in patients with LBBB. Hypothesis Increased septal wall stress causes septal dysfunction in LBBB. Methods We included 24 LBBB-patients (65 ± 11 years, 11 males) with LV ejection fraction (EF) ranging from 18 to 67%, and 8 healthy controls (58 ± 10 years, 4 males). Wall stress was calculated at peak LV pressure (LVP) according to the law of La Place ([LVP x radius]/[wall thickness]). Wall thickness was measured using M-mode, and regional curvature was measured in mid-ventricular shortaxis from 2D echocardiographic images. We used a previously validated non-invasive method to estimate LVP from brachial blood pressure and adjusted for valvular events. Myocardial scar was ruled out by late gadolinium enhancement cardiac magnetic resonance imaging. Results Wall stress was significantly higher in septum than LV lateral wall at peak LVP (48 ± 12 vs 37 ± 11 kPa, p < 0.01) in LBBB patients, while no difference was seen in the controls (Figure A). In patients, septal wall thickening showed a strong correlation with LVEF (r = 0.77, p < 0.01) (Figure B). Similar correlation was not significant for the LV lateral wall (r = 0.13, NS). Attenuation of septal wall thickening in LBBB-patients correlated well with increasing septal wall stress (r=-0.60, p < 0.01). Wall thickening and stress did not correlate in the LV lateral wall (r=-0.14, NS). Conclusion Increased septal wall stress is associated with reduced systolic thickening in patients with LBBB. Septal wall thickening, in contrast to LV lateral wall thickening, was correlated to global LV function. These findings suggest that septal remodeling which could have normalized septal wall stress, was not achieved and heart failure may develop. Abstract Figure.

Mechanism of prolonged electromechanical delay in late activated myocardium during left bundle branch block

2011 ◽  
Vol 301 (6) ◽  
pp. H2334-H2343 ◽  
Author(s):  
Kristoffer Russell ◽  
Otto A. Smiseth ◽  
Ola Gjesdal ◽  
Eirik Qvigstad ◽  
Per Andreas Norseng ◽  
...  
Keyword(s):  
Papillary Muscle ◽  
Left Bundle Branch Block ◽  
Biventricular Pacing ◽  
Lateral Wall ◽  
Mechanical Dyssynchrony ◽  
Left Ventricular ◽  
Electromechanical Delay ◽  
Bundle Branch Block ◽  
Experimental Findings

During left bundle branch block (LBBB), electromechanical delay (EMD), defined as time from regional electrical activation (REA) to onset shortening, is prolonged in the late-activated left ventricular lateral wall compared with the septum. This leads to greater mechanical relative to electrical dyssynchrony. The aim of this study was to determine the mechanism of the prolonged EMD. We investigated this phenomenon in an experimental LBBB dog model ( n = 7), in patients ( n = 9) with biventricular pacing devices, in an in vitro papillary muscle study ( n = 6), and a mathematical simulation model. Pressures, myocardial deformation, and REA were assessed. In the dogs, there was a greater mechanical than electrical delay (82 ± 12 vs. 54 ± 8 ms, P = 0.002) due to prolonged EMD in the lateral wall vs. septum (39 ± 8 vs.11 ± 9 ms, P = 0.002). The prolonged EMD in later activated myocardium could not be explained by increased excitation-contraction coupling time or increased pressure at the time of REA but was strongly related to dP/d t at the time of REA ( r = 0.88). Results in humans were consistent with experimental findings. The papillary muscle study and mathematical model showed that EMD was prolonged at higher dP/d t because it took longer for the segment to generate active force at a rate superior to the load rise, which is a requirement for shortening. We conclude that, during LBBB, prolonged EMD in late-activated myocardium is caused by a higher dP/d t at the time of activation, resulting in aggravated mechanical relative to electrical dyssynchrony. These findings suggest that LV contractility may modify mechanical dyssynchrony.

scholarly journals Bilateral Bundle Branch Area Pacing to Achieve Physiological Conduction System Activation

2020 ◽  
Vol 13 (8) ◽  
Author(s):  
Jinxuan Lin ◽  
Keping Chen ◽  
Yan Dai ◽  
Qi Sun ◽  
Yuqiu Li ◽  
...  
Keyword(s):  
Right Ventricular ◽  
Right Bundle Branch Block ◽  
Left Ventricular ◽  
Conduction System ◽  
Conduction Delay ◽  
Activation Time ◽  
Bundle Branch Block ◽  
Ventricular Activation ◽  
Qrs Duration ◽  
The Right

Background: Left bundle branch pacing (LBBP) is a technique for conduction system pacing, but it often results in right bundle branch block morphology on the ECG. This study was designed to assess simultaneous pacing of the left and right bundle branch areas to achieve more synchronous ventricular activation. Methods: In symptomatic bradycardia patients, the distal electrode of a bipolar pacing lead was placed at the left bundle branch area via a transventricular-septal approach. This was used to pace the left bundle branch area, while the ring electrode was used to pace the right bundle branch area. Bilateral bundle branch area pacing (BBBP) was achieved by stimulating the cathode and anode in various pacing configurations. QRS duration, delayed right ventricular activation time, left ventricular activation time, and interventricular conduction delay were measured. Pacing stability and short-term safety were assessed at 3-month follow-up. Results: BBBP was successfully performed in 22 of 36 patients. Compared with LBBP, BBBP resulted in greater shortening of QRS duration (109.3±7.1 versus 118.4±5.7 ms, P <0.001). LBBP resulted in a paced right bundle branch block configuration, with a delayed right ventricular activation time of 115.0±7.5 ms and interventricular conduction delay of 34.0±8.8 ms. BBBP fully resolved the right bundle branch block morphology in 18 patients. In the remaining 4 patients, BBBP partially corrected the right bundle branch block with delayed right ventricular activation time decreasing from 120.5±4.7 ms during LBBP to 106.1±4.2 ms during BBBP ( P =0.005). Conclusions: LBBP results in a relatively narrow QRS complex but with an interventricular activation delay. BBBP can diminish the delayed right ventricular activation, producing more physiological ventricular activation. Graphic Abstract: A graphic abstract is available for this article.

Abstract 14295: Increasing QRS Duration Over Time Is Associated With Mortality and Morbidity in an Outpatient Heart Failure Population

Circulation ◽  
2015 ◽  
Vol 132 (suppl_3) ◽  
Author(s):  
Hassan Alfraidi ◽  
William F McIntyre ◽  
Lindsay Torbiak ◽  
Shelley Zieroth ◽  
Colette M Seifer
Keyword(s):  
Heart Failure ◽  
Systolic Function ◽  
Nyha Class ◽  
Tertiary Care ◽  
Left Ventricular ◽  
Conduction Delay ◽  
Mortality And Morbidity ◽  
Qrs Duration ◽  
Lv Systolic Function ◽  
Over Time

Introduction: Heart failure is a leading cause of morbidity and mortality. Prolonged QRS duration (QRSd), a marker of intra-ventricular conduction delay, has been shown to be associated with worse left ventricular (LV) systolic function, LV dilation and mitral regurgitation as well as with mortality. There are minimal data in the literature on the progression of QRSd over time, and the association with clinical outcomes. Hypothesis: We hypothesized that the progression of QRSd over time would be associated with mortality and hospitalizations in an outpatient heart failure population. Methods: Retrospective study of consecutive new adult referrals to a tertiary heart failure clinic over a 1 year period (2012). All patients with a narrow QRSd (defined as <130 ms) were included. Data were collected on demographics, ejection fraction (EF), clinical course and major clinical events. Primary endpoint was mortality and secondary endpoint was heart failure hospitalization. Results: A total of 147 patients were included, 90 were males (61%). Mean age was 66 years (+/-15), mean EF was 33% (+/- 15) and mean NYHA class 2.2 (+/- 0.9) at baseline. An ischemic aetiology accounted for 50% of the patients. Mean QRSd was 100 ms (+/- 13) at baseline and 119 ms (+/- 25) at last follow-up, which was a mean of 2.5 years from baseline. Death occurred in 27 patients (18%) and there were 114 hospitalizations in 54 patients. Results of univariate regression analysis are presented in the table. Conclusion: An increase in QRSd over time is associated with increased heart failure hospitalizations and all cause mortality in a tertiary care outpatient heart failure population.

scholarly journals Obesity in the absence of comorbidities is not related to clinically meaningful left ventricular hypertrophy

2021 ◽  
Author(s):  
Andrew J. M. Lewis ◽  
Jennifer J. Rayner ◽  
Ines Abdesselam ◽  
Stefan Neubauer ◽  
Oliver J. Rider
Keyword(s):  
Wall Thickness ◽  
Ventricular Hypertrophy ◽  
Severe Obesity ◽  
Lateral Wall ◽  
Left Ventricular ◽  
Septal Wall ◽  
Diagnostic Uncertainty ◽  
Significant Difference ◽  
Septal Wall Thickness ◽  
Basal Septum

AbstractObesity is associated with the development of left ventricular (LV) hypertrophy. Whether obesity in in the absence of comorbidities can cause LV hypertrophy to an extent which could create diagnostic uncertainty with pathological states (such as hypertrophic cardiomyopathy) is unknown. We used cine cardiovascular magnetic resonance imaging to precisely measure LV wall thickness in the septum and lateral wall in 764 people with body mass indices ranging from 18.5 kg/m2 to 59.2 kg/m2 in the absence of major comorbidities. Obesity was related to LV wall thickness across the cohort (basal septum r 0.30, P < 0.001 and basal lateral wall r 0.18, P < 0.001). Although no participant had hypertension, these associations remained highly significant after controlling for systolic blood pressure (all P < 0.01). Each 10 kg/m2 increase in BMI was associated with an increase in basal septal wall thickness of 1.0 mm males and 0.8 mm in females, with no statistically significant difference between genders (P = 0.1). Even in class 3 obesity (BMI > 40 kg/m2), no LV wall thickness > 13.4 mm in males or > 12.7 mm in females was observed in this cohort. We confirm that obesity in the absence of comorbidities is associated with LV hypertrophy, and establish that the magnitude of this change is modest even in severe obesity. LV hypertrophy > 14 mm cannot safely be attributed to obesity alone and alternative diagnoses should be considered.

scholarly journals Changes in mechanics of septal and lateral walls in patients with left bundle-branch block are related to extent of systolic dysfunction

2021 ◽  
Vol 22 (Supplement_1) ◽  
Author(s):  
K Kupczynska ◽  
KA Nguyen ◽  
E Surkova ◽  
CH Palermo ◽  
F Sambugaro ◽  
...  
Keyword(s):  
Left Bundle Branch Block ◽  
Systolic Dysfunction ◽  
Lateral Wall ◽  
Left Ventricular ◽  
Public Institution ◽  
Healthy Controls ◽  
Bundle Branch Block ◽  
Funding Sources ◽  
Lv Dysfunction ◽  
Artery Disease

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): Karolina Kupczynska was supported by research grant awarded by the Club 30 of the Polish Cardiac Society Background Left bundle branch block (LBBB) affects left ventricular (LV) mechanics and promotes systolic dysfunction. Purpose To analyse myocardial work (MW) and myocardial work efficiency (MWE) of the septal and LV lateral wall in healthy controls and LBBB patients with various degrees of LV dysfunction using non-invasive method. Methods Our study involved 102 healthy controls (mean age 41.5 ± 15.7 years, 45% male) and 58 LBBB patients without coronary artery disease (mean age 65 ± 13 years, 60% male) divided into 3 groups based on their LVEF: preserved (n= 27), mid-range (n= 16) and reduced (n= 15). Myocardial work parameters were estimated in septal and lateral wall by LV pressure-strain loop obtained by echocardiography. Results There were no differences between septal and lateral MW and MWE in healthy controls (p = NS). We found lower septal MW in comparison to lateral MW (p &lt; 0.0001), but there were no differences in MWE (p = NS) in LBBB patients with preserved LVEF. Patients with LBBB and mid-range or reduced LVEF had lower MW (p &lt; 0.0001 in both subgroups) and lower MWE (p = 0.002 and p = 0.0001, respectively) in septum compared with lateral wall. There was a progressive decrease in septal MW and MWE with the occurring of LBBB and the worsening of LVEF (figure A). Interestingly in healthy controls there was significantly lower lateral MW but higher MWE in comparison to group with LBBB and preserved LVEF. We did not detect differences between LBBB groups with preserved and mid-range LVEF, but patients with reduced LVEF had significant reduction in terms of lateral MW and MWE (figure B). Conclusions Impairment in septal myocardial work escalated according to the appearance of LBBB and LVEF loss. Septal dysfunction was compensated by the effective myocardial work of the lateral wall in LBBB patients with preserved and mid-range LVEF. Mechanical dysfunction of the lateral wall was associated with severely reduced LVEF. Abstract Figure.

Abstract P64: Right Ventricular Outflow Septal Pacing as Cardiac Resynchronization Therapy in Patients with Right Bundle-Branch Block: Results in 62 Patients

2011 ◽  
Vol 4 (suppl_2) ◽  
Author(s):  
Phillip E Schrumpf ◽  
Michael Giudici ◽  
Deborah Paul ◽  
Roselyn Krupa ◽  
Cynthia Meirbachtol
Keyword(s):  
Cardiac Resynchronization Therapy ◽  
Right Ventricular ◽  
Right Bundle Branch Block ◽  
Left Ventricular ◽  
Cardiac Resynchronization ◽  
Qrs Complex ◽  
Resynchronization Therapy ◽  
Ventricular Performance ◽  
Bundle Branch Block ◽  
Qrs Duration

Background: Cardiac resynchronization therapy has been shown to improve left ventricular performance in patients with left ventricular dysfunction and a left-sided interventricular conduction delay. This is performed by placing a pacing lead on the lateral left ventricular wall to stimulate the area normally stimulated by the left bundle branch. In patients with right bundle branch block (RBBB), pacing the right bundle branch could also result in resynchronization. Previous studies have shown that right ventricular outflow septal (RVOS) pacing does, in fact, utilize the native conduction system. Methods: 62 consecutive patients, 46 male/16 female, aged 75 +/− 10.5 yr, with RBBB and indications for pacing, underwent RVOS lead placement using commercially available pacing systems. The patients subsequently underwent bedside A-V optimization to achieve the narrowest QRS duration and most “normal” QRS complex. Echocardiography was performed to evaluate changes in wall motion comparing baseline with optimal pacing. Results: Baseline mean QRS duration 146 +/− 20.9 ms Optimized mean QRS duration 111 +/− 20.5 ms Average decrease in QRS duration -35 +/− 21.5 ms p < 0.001 Echocardiography demonstrated improvement in septal contraction abnormalities. Conclusions: 1) RVOS pacing in RBBB patients can significantly narrow the QRS complex on ECG. 2) Septal contraction abnormalities due to RBBB can be improved with RVOS pacing and optimal A-V timing. 3) Further studies are warranted to evaluate this therapy in a heart failure population.

Abstract 13286: Non-Specific Intraventricular Conduction Delay and Risk of Sudden Death

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Audrey Uy-Evanado ◽  
Carmen Teodorescu ◽  
Kyndaron Reinier ◽  
Kumar Narayanan ◽  
Harpriya Chugh ◽  
...  
Keyword(s):  
Sudden Cardiac Death ◽  
General Population ◽  
Left Bundle Branch Block ◽  
Cardiac Death ◽  
Conduction Delay ◽  
Bundle Branch Block ◽  
Intraventricular Conduction ◽  
Qrs Morphology ◽  
Qrs Duration ◽  
Intraventricular Conduction Delay

Introduction: We and others have reported an independent association between prolonged QRS duration and risk of sudden cardiac death (SCD) in the general population. Left and right bundle branch block have been studied previously, but there is little information regarding non-specific intraventricular conduction delay and risk of SCD. Hypothesis: Completed conduction defects, including non-specific IVCD, are associated with increased SCD risk. Methods: Sudden cardiac death cases and controls from an ongoing large population based study in the Northwestern US (2002 to 2010) were included if age ≥ 35 years with a non-paced 12-lead ECG (recorded prior and unrelated to SCD in cases). QRS morphology was subcategorized as normal, intermediate [left anterior fascicular block (LAFB), left posterior fascicular block (LPFB), and incomplete right or left bundle branch block (IRBBB/ILBBB)] or completed conduction defects [left bundle branch block (LBBB), right bundle branch block (RBBB), or nonspecific intraventricular conduction delay (IVCD)]. Comparisons were conducted using chi-square tests for categorical variables and independent samples t-tests for continuous variables. Logistic regression was used to evaluate the association of QRS morphology with SCD. Results: We evaluated 761 SCD cases (64% male) and 539 controls (65% male). Cases were significantly older (69.7 vs 66.3 years, p<0.0001) with greater QRS duration (102 vs. 98 ms, p=0.001). For conduction categories, intermediate or completed conduction defects were significantly more common in cases whereas normal QRS morphology was more common among controls (p=0.01). And for specific morphology overall, QRS morphology patterns differed between cases and controls (p=0.03); abnormal QRS morphologies were more frequent in cases than controls except for LAFB. After adjustment for age and gender, however, only a finding of LBBB or non-specific IVCD remained a significant predictor of SCD [OR 1.34 (95% CI 1.03-1.75)]. Conclusions: LBBB and non-specific IVCD, but not RBBB, are significant predictors of SCD in the general population. These findings contribute to the utility of the 12-lead EKG for SCD risk stratification.

scholarly journals Imaging predictive factors and exercise training in CRT patients

2016 ◽  
Vol 86 (1-2) ◽  
Author(s):  
Ana Abreu ◽  
Helena Santa Clara
Keyword(s):  
Single Photon ◽  
Imaging Techniques ◽  
Photon Emission ◽  
Mechanical Dyssynchrony ◽  
Left Ventricular ◽  
Cardiac Resynchronization ◽  
Conduction Delay ◽  
Lv Function ◽  
Scar Burden ◽  
Intraventricular Conduction

<p>Cardiac resynchronization therapy (CRT) is an established treatment for patients with moderate-to-severe chronic heart failure (CHF) and intraventricular conduction delay, which is identified by a QRS interval of 120msec or more on a 12-lead electrocardiogram (ECG). CRT improved functional capacity, reduced hospitalizations for worsening CHF and increased survival. However, about 30-40% of patients who underwent CRT were non-responders with no clinical or echocardiographic improvement. Imaging parameters for prediction of CRT response have been reviewed. Cardiac magnetic resonance (CMR), recognized as the gold standard to assess viability, has shown to obtain good results regarding quantification of scar burden. CMR-derived measures of mechanical dyssynchrony appear to predict the outcome of CRT, however they have not been externally validated. Nuclear imaging techniques, namely single-photon emission cardiac tomography (SPECT) provide data on scar burden and location, left ventricular (LV) function, LV contraction and mechanical dyssynchrony from a single scan. The presence, location and burden of myocardial scar have been shown to affect response to CRT. However, compared to CMR, the low spatial resolution of scintigraphy might overestimate the scar extent. This problem can be overcome by positron emission tomography (PET). SPECT has also been used to quantify dyssynchrony, using phase analysis. Imaging investigation is ongoing, trying to better identifying CRT non-responders. The combination of ExT in CRT has not been well investigated; however some data show different aerobic exercise modes and intensities can further improve CRT benefits. Data available on the effects of ExT in patients with CRT have been reviewed.</p>

scholarly journals Relationship between left bundle branch block patterns and super-response to cardiac resynchronization therapy in patients with heart failure

2021 ◽  
Vol 26 (7) ◽  
pp. 4227
Author(s):  
N. E. Shirokov ◽  
V. A. Kuznetsov ◽  
V. V. Todosiychuk ◽  
A. M. Soldatova ◽  
D. V. Krinochkin
Keyword(s):  
Cardiac Resynchronization Therapy ◽  
Left Bundle Branch Block ◽  
Interventricular Septum ◽  
Left Ventricular ◽  
Doppler Imaging ◽  
Cardiac Resynchronization ◽  
Resynchronization Therapy ◽  
Bundle Branch Block ◽  
Septal Wall ◽  
Group I

Aim. To assess a relationship of left bundle branch block (LBBB) patterns defined by electrocardiography (ECG) and echocardiography with super-response (SR) to cardiac resynchronization therapy (CRT).Material and methods. Sixty patients (mean age, 54,5±10,4 years) were examined at baseline and during follow-up (10,6±3,6 months). Patients were divided into groups: group I (n=31) — decrease of left ventricular end-systolic volume (ESV) ≥30% (super-responders) and II group (n=29) — decrease of LV ESV <30% (non-super-responders). Three strain-markers of LBBB assessed by tissue Doppler imaging (TDI) and speckle tracking echocardiography (STE) were used: early contraction of basal or midventricular segment in the septal wall and early stretching of basal or midventricular segment in the lateral wall (marker 1); early peak contraction of the septal wall occurred in the first 70% of the systolic ejection phase (marker 2, septal flash (SF)); early stretching wall that showed peak contraction after aortic valve closure (marker 3). The classical LBBB pattern was defined if all three strain-markers were present. The heterogeneous LBBB pattern was defined if two from three strain-markers were present.Results. At baseline, groups did not differ in main clinical characteristics, including QRS width and LBBB assessed by ECG. Mechanical abnormalities were found only in group I: SF (32,3% vs 0,0%; p=0,001) and apical rocking (19,4% vs 0,0%; p=0,024), as well as classic LBBB mechanical pattern (20,8% vs 0,0%; p=0,05). The complex of heterogeneous LBBB mechanical pattern (odds ratio (OR), 7,512; 95% CI, 1,434-39,632; р=0,025), interventricular mechanical delay (OR, 1,037; 95% CI, 1,005-1,071; р=0,017) and longitudinal strain of interventricular septum mid segment (OR, 0,726; 95% CI, 0,540-0,977; р=0,035) had an independent relationship with SR. According to the ROC analysis, the sensitivity and specificity of model in SR prediction were 77,3% and 91,3% (AUC=0,862; p<0,001).Conclusion. SR is associated with both LBBB mechanical patterns assessed by STE and TDI. LBBB defined by ECG did not have significant association with SR to CRT.

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