Left Bundle Branch Block Chest Pain Conundrum.

Left bundle branch block is a pattern of altered ventricular depolarization and subsequently affects repolarization. These obscure patterns can affect the traditional ST segment shift criteria for the electrocardiographic detection of coronary insufficiency syndromes. Previously, patients with coronary ischemic pain and LBBB judged to be "new" (not previously documented) were considered to have ST elevation myocardial infarction (STEMI) warranting acute thrombolytic therapy. Current STEMI management favors emergent invasive angiography; however, recent data suggests the prevalence of coronary obstructive pathology may be as low as 50%. The application of more specific, less-sensitive Sgarbossa electrocardiographic criteria may reduce angiographic assessment in an otherwise high-risk population unlikely to tolerate further myocardial injury. We present a case that may facilitate a more nuanced EKG-based approach to distinguish those who may benefit from acute invasive angiography while reducing the frequency of unnecessary angiographic evaluation.