Episodic Left Bundle Branch Block-A Comprehensive Review of the Literature

Abstract

Episodic (transient/ intermittent) left bundle branch block (LBBB) has been associated with different conditions such as bradycardia, tachycardia, anesthesia, acute pulmonary embolism, changes in intrathoracic pressure, chest trauma, cardiac interventional procedures, mad honey poisoning, and in other clinical settings. Of note, exclusion of an acute coronary syndrome in the setting of episodic LBBB is of great importance. Moreover, episodic LBBB is sometimes symptomatic and may be associated with left ventricular systolic and/or diastolic dysfunction or conduction disturbances leading to syncope. This review article provides a comprehensive overview of the conditions associated with episodic LBBB and discusses the clinical impact of this phenomenon.

Keywords: Intermittent; cardiac memory; left bundle branch block; rate-dependent; transient.

Figure 1

(A). ECG strips from a patient showing transient LBBB. (B) ECG strips from the same patient a few hours later showing normal QRS.

Figure 2

Rate‐related LBBB with premature atrial contractions and supernormal conduction. ECG strip downloaded from: http://ecgguru.com/blog/jasons-blog-ecg-challenge-week-march-3rd-10th. Free license: http://creativecommons.org/licenses/by-nd-nc/1.0/.