Ticagrelor-Induced Complete Heart Block

A young male in his mid-30s presented with acute onset of severe, retrosternal chest pain of 12 hours' duration. 12-lead electrocardiogram showed ST-segment elevation in chest leads V1-V6, confirming a diagnosis of anterior wall myocardial infarction (AWMI). He was taken up for urgent coronary angiography, which revealed a proximal left anterior descending (LAD) thrombotic lesion (other coronaries being completely normal). Primary percutaneous coronary intervention (PCI) was performed, deploying a 3.5×33 mm stent from the LAD artery ostium, with TIMI 3 flow. The patient was initiated on dual antiplatelet therapy with aspirin and ticagrelor. On day two, the patient experienced multiple episodes of syncope and was found to have complete heart block (CHB) with a heart rate dropping to 30 beats per minute. A temporary transvenous pacemaker was inserted, and after ruling out all possible reversible etiologies, a check angiogram was done. It revealed a patent stent with TIMI 3 flow in the LAD, and all other vessels were normal. Ticagrelor was suspected as a plausible cause of CHB and was substituted with clopidogrel. This was followed by an intermittent return to sinus rhythm within 24 hours and complete resolution of CHB by 40 hours with no further episodes of CHB occurring after 48hours of discontinuation of ticagrelor. This case highlights the potential for ticagrelor-induced CHB even in young individuals without any preexisting conduction system disease and the importance of early recognition and prompt management, which can prove to be lifesaving.