SUMMARY Rate-dependent intermittent incomplete and complete left bundle-branch block (LBBB) is described in a patient without other evidence of heart disease. Continuous electrocardiographic tracings revealed QRS complexes intermediate in configuration between normal conduction and complete LBBB during the transitional phase from normal to abnormal conduction. This provided an opportunity to st...

OBJECTIVES We sought to separate the effects of associated left bundle branch block (LBBB) and coronary artery disease (CAD) on peak cardiac output (CO) during dobutamine stress in patients with dilated cardiomyopathy (DCM). BACKGROUND The mechanisms limiting CO during stress in patients with DCM are unclear. Both LBBB and CAD may do so by prolonging the total isovolumic time (t-IVT). METHO...

BACKGROUND Exercise-induced left bundle branch block (EI-LBBB) is an infrequent finding. Its prevalence and prognostic significance are not clear. OBJECTIVE To evaluate, in a longitudinal study, the prevalence and prognostic significance of EI-LBBB in American war veterans. METHODS We evaluated 9,623 patients submitted to an exercise test (ET) in treadmill between 1987 and 2007. The outcome...

BACKGROUND Left bundle branch block (LBBB) is associated with atrial fibrillation (AF) and systolic heart failure, which can be treated with cardiac resynchronization therapy (CRT) that includes an implantable cardiac device (ICD). However, in some patients, LBBB may vary with heart rate, and during episodes of AF in LBBB, aberrant ventricular conduction, or wide QRS complex tachycardia (Ashman...

BACKGROUND This study aimed to determine whether QRS morphology identifies patients who benefit from cardiac resynchronization therapy with a defibrillator (CRT-D) and whether it influences the risk of primary and secondary end points in patients enrolled in the Multicenter Automatic Defibrillator Implantation Trial-Cardiac Resynchronization Therapy (MADIT-CRT) trial. METHODS AND RESULTS Base...

AIMS Cardiac conduction disturbances, including a left bundle branch block (LBBB), occur frequently following transcatheter aortic valve replacement (TAVR) and may be associated with adverse clinical events. This analysis examines the incidence and implications of new onset, persistent LBBB in patients undergoing TAVR with a balloon-expandable valve. METHODS AND RESULTS Patients undergoing TA...

Examination of ECGs in patients with intermittent left bundle branch block (LBBB) may provide insight into mechanisms and cause of LBBB. In this study, we obtained ECG files of patients with intermittent LBBB by mail solicitation of cardiologists. The group suitable for analysis included 275 patients in whom both LBBB was documented and at least one 12-lead ECG was available which demonstrated ...

Total body surface maps from 15 subjects with left bundle branch block and normal axis (LBBB-NA) and 10 subjects with left bundle branch block and left axis (LBBB-LA) were analyzed and compared with maps from normal subjects. In 19 of the 25 subjects with LBBB, the timing of early upper sternal positivity was similar to that of normal subjects, indicative of timely but oppositely directed septa...

Up to 40% of healthy children have premature ventricular complexes or contractions (PVCs) detected with 24-hour Holter monitoring. We aimed to investigate the morphological characteristics and origins of idiopathic PVCs under a 12-lead electrocardiogram in children with structurally normal hearts. All asymptomatic monomorphic PVC patients with structurally normal hearts under 18 years of age we...

AIMS The current guidelines recommend reperfusion therapy in acute myocardial infarction (AMI) with ST-segment elevation or left bundle branch block (LBBB). Surprisingly, the right bundle branch block (RBBB) is not listed as an indication for reperfusion therapy. This study analysed patients with AMI presenting with RBBB [with or without left anterior hemiblock (LAH) or left posterior hemiblock...