Left Septal Fascicular Block without and with ST-Segment Elevation

We present a case where left septal fascicular block precedes anterior STEMI. Our case calls the attention to severe ischaemia-related left septal fascicular block could be an early red flag sign for proximal left anterior descending coronary artery critical stenosis. In our case the causative mechanism of prominent anterior forces in the setting of an acute anterior ST-elevation is left septal fascicular block.