Transient left septal fascicular block in the scenario of ST-segment elevation myocardial infarction

Özet

Although the conduction abnormalities of the left anterior and posterior fascicles, left anterior fascicular block (LAFB), and left posterior fascicular block (LPFB) are commonly diagnosed and well-known to physicians, the abnormalities of the left septal fascicle (LSF) and left septal fascicular block (LSFB), are easily overlooked because most physicians are not aware of the existence of the LSF. LSFB exclusively affects precordial leads without modifying the ECG in the frontal plane, causing prominent anterior QRS forces. LSF is irrigated exclusively by the left anterior descending (LAD) coronary artery, and therefore, LAD occlusion can result in LSFB. We report a case with transient LSFB in the scenario of ST-segment elevation myocardial infarction (STEMI) because of acute occlusion of LAD.