R-on-T Phenomenon Causing Cardiac Arrest in a Post-coronary Artery Bypass Graft (CABG) Patient

Cardiac arrhythmias are common in post-coronary artery bypass graft (CABG) settings. It is a common practice to use temporary epicardial pacing wires at the end of cardiac surgery to prevent fatal arrhythmias (e.g., bradycardia,atrioventricular (AV) block, and asystole). It may also be used for sequential atrio-ventricular pacing for improved cardiac output in patients with poor ejection fraction. Epicardial wires are usually implanted around the right atrium and ventricle. Not every patient requires temporary epicardial pacing. However, certain risk factors may predispose patients to life-threatening AV blocks and ventricular tachyarrhythmias. These risk factors include advancing age, valvular surgery, poor left ventricular function, structural heart disease, diabetes mellitus, preoperative beta-blocker or digoxin use, and pre-existing history of arrhythmias. Only a handful of cases have been described in the literature where this seemingly lifesaving measure can trigger life-threatening events. Here, we describe a case where epicardial pacing wires trigger ventricular arrhythmias due to improper sensing.