Likewise in the RAFT trial LBBB pts showed more benefit from CRT in terms of death or hospitalization for heart failure compared to pts with RBBB, non-specific intraventricular conduction disturbance (IVCD) or paced QRS at baseline. In CRT pts a baseline left bundle branch block (LBBB) has been demonstrated to be associated with a more favorable prognosis in terms of freedom from death or major cardiovascular events, and with a more left ventricular (LV) reverse remodeling compared to a baseline right bundle branch block (RBBB). Several parameters of electrical and mechanical dyssynchrony have been proposed to improve pt selection, even though QRS duration is currently the only recommended parameter. However clinical and/or echocardiographic response is present in only 50-70% of CRT pts, suggesting that the link between standard criteria for CRT and expected response is often weak. Pts with non-LBBB pattern show significantly less benefit from CRT than those with LBBB.Ĭardiac resynchronization therapy (CRT) reduces morbidity and mortality in patients (pts) with congestive heart failure improving clinical status and favoring ventricular reverse remodeling. Presence of a LBBB is a marker of a positive response to CRT in terms of biventricular improvement. At multivariate analysis, LBBB was the only predictor of LVEF response (OR, 7.45 95% CI 1.80-30.94 p = 0.006), but not QRS duration or extent of mechanical dyssynchrony. RVEF was significantly improved in LBBB (+5.0 ± 9.0%, p = 0.007), but not in non-specific IVCD and RBBB pts (+0.4 ± 5.8%, p = 0.76). 24% of non-specific IVCD pts (p = 0.006). Response (defined as ≥ 5% increase in LVEF) was observed in 68% of LBBB vs. LBBB pts had significantly greater improvement in LVEF compared to RBBB or non-specific IVCD pts (+9.6 ± 10.9% vs. We enrolled 56 pts, 32 with left bundle branch block (LBBB), 4 with right bundle branch block (RBBB) and 20 with non-specific intraventricular conduction disturbance (IVCD). Changes in left and right ventricular EF (LVEF and RVEF) were analyzed with regard to baseline QRS pattern. The relationship between baseline QRS pattern and mechanical dyssynchrony using phase analysis was evaluated. MethodsĬonsecutive patients (pts) undergoing CRT implantation underwent radionuclide angiography at baseline and at mid-term follow-up. We evaluated the role of baseline QRS pattern to predict response in terms of improvement in biventricular ejection fraction (EF). Ann Noninvasive Electrocardiol 2017 Jan 22.Predicting response to cardiac resynchronization therapy (CRT) remains a challenge. Left Bundle Branch Block and Complete Heart Block Complicating Inferior Myocardial Infarction. Gruber JS, Stair B, Aktas M, Bravo-Jaimes K.Electrocardiographic "Peri-Infarction Block" A Clinical and Pathologic Correlation. The R > S in V2 with upright T wave in V1 suggests posterior infarction as well. Therefore, intraventricular conduction defect (IVCD) has been used instead of infarction block. Though the changes in the QRS have been historically labeled as infarction block in patients with myocardial infarction, they are not specific and have been described in patients with non-ischemic cardiomyopathy, myocardial fibrosis, and chronic lung disease with emphysema, and in patients without lung or heart disease. This is indicative of infarction block of the inferior wall. The QRS forces point leftward and superiorly producing Q waves in leads II, III, and aVF with slow terminal forces directed 180 degrees opposite the inferior Q's, producing an S wave in lead aVL and lead I, which is not seen well in this ECG. The QRS is usually wide (> or equal to100 milliseconds: "it is approximately 130 milliseconds in our patient"). Intraventricular conduction defect (IVCD) following myocardial infarction is common. The initial and terminal forces are approximately 180 degrees, which represents infarction block or intraventricular conduction defect (IVCD). Beats 3 and 7 are premature atrial beats, which are conducted with normal atrioventricular conduction and QRS demonstrating inferior infarction of undetermined age with prolonged QRS duration. The ECG shows appropriate demand atrioventricular pacing.
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