A 50 year old man presents with central chest pain. He collapsed while his ECG was being recorded. What is the cause of this ECG?
High-Yield Explanation
ECG shows ST segment changes in lead II, III indicating inferior wall MI (BLUE ARROW) Ventricular extra-systole after the first beat (RED MARK) In the fouh beat, ventricular Extra-systole (YELLOW) is occurring at time of T wave triggering a polymorphic Ventricular tachycardia. The "R-on-T phenomenon" is the superimposition of an ectopic beat on the T wave of a preceding beat which triggers Polymorphic VT.