Left posterior fascicular block, state-of-the-art review: A 2018 update

Abstract

We conducted a review of the literature regarding epidemiology, clinical, electrocardiographic and vectorcardiographic aspects, classification, and differential diagnosis of left posterior fascicular block.Isolated left posterior fascicular block (LPFB) is an extremely rare finding both in the general population and in specific patient groups. In isolated LPFB 20% of the vectorcardiographic (VCG) QRS loop is located in the right inferior quadrant and when associated with right bundle branch block (RBBB) ≥40%.The diagnosis of LPFB should always consider the clinical aspects, because a definite diagnosis cannot be made in the presence of right ventricular hypertrophy (RVH) (chronic obstructive pulmonary disease (COPD)/emphysema), extensive lateral myocardial infarction (MI) or extremely vertical heart.Intermittent LPFBs are never complete blocks (transient or second degree LPFB) and even in the permanent ones, one cannot be sure that they are complete. When LPFB is associated with RBBB and acute inferior MI, PR interval prolongation is very frequent.

Syncope in the setting of trifascicular block and retrograde concealed conduction: A case report

“…Bearing in mind that the patient in the present study had trifascicular block with LPH, the latter being associated with structural heart disease and/or significant pathology in the conduction system ( 3 ), it is possible that the dropped sinus beats may have been falsely attributed to atrioventricular block. However, these non-conducted sinus beats occurred only after the PVCs.…”

Relation of intraventricular conduction delay to risk of new-onset heart failure and structural heart disease in the general population

“…Study data on the relation between LPFB and HF is scarce, as LPFB is an extremely rare finding both in the general population and in specific patient groups. As an entity, LPFB may occur in infiltrative cardiomyopathies [38] , and LPFB with or without RBBB may be found in cases with Chagas disease [39] , which is an important cause of cardiomyopathy in Latin America. No increased risk of HF or SHD was found in subjects with LPFB in this study but the low number of subjects prohibit any definitive conclusions to be drawn.…”

Long‐term outcome of intraventricular conduction delays in the general population

“…Left anterior fascicular block (LAFB) is usually regarded as a conduction disorder without clinical significance if encountered in asymptomatic individuals (Elizari, Acunzo, and Ferreiro, 2007). Isolated left posterior fascicular block (LPFB) is a rare conduction disorder with no clear consensus on prognostic significance without CV disease (Pérez‐Riera et al., 2018). Previous scientific literature does not provide much information about the prevalence or prognostic significance of incomplete bundle branch blocks in individuals apparently free of CV disease.…”