Post-CABG R-on-T phenomenon progressed to Torsades de Pointes and ventricular fibrillation in a 75-year-old woman, which was successfully terminated with defibrillation and medical therapy.
Case Report (n=1)
This case highlights the critical importance of continuous telemetry monitoring and aggressive electrolyte management to prevent and treat potentially fatal R-on-T phenomenon and Torsades de Pointes in the immediate post-CABG period.
Abstract Introduction Up to 40% of the patients undergoing coronary artery bypass grafting (CABG) develop post-operative atrial fibrillation, where as R on T phenomenon is rare (0.4 - 1.4%) and occurs when a premature ventricular complex falls on the preceding T wave. This phenomenon in turn can lead to development of Torsades de Pointed (TdP) which can be fatal if not managed in a timely manner. We present such a case where pure R on T phenomenon progressed to Torsades within few hours post CABG. Case Report A 75 year old woman with Diabetes, Hypertension and hyperlipidemia underwent elective CABG for a three vessel CAD. Preoperative ejection fraction (EF) was noted to be 55 - 60%. A few hours postoperatively and while intubated, telemetry revealed loss of R wave progression in V2 - V4 and progressive QTc prolongation. Electrolytes were repleted but shortly after, telemetry captured a PVC landing on the preceding T wave (R on T) which developed into Torsades and ventricular fibrillation which required defibrillation along with magnesium, lidocaine and aggressive potassium repletion. She was started on Amiodarone to prevent further arrhythmias. Post operative echo showed preserved EF. She did not have any further episodes of arrhythmias and was extubated on day 5 and discharged on day 9. Discussion and importance of the case Post operative myocardium is prone to altered conduction pathways, reperfusion injury, increased automaticity, electrolyte abnormalities due to intra operative losses and stunning. R on T phenomenon occurs when T wave encounters a PVC during the relative refractory period due to variable repolarization and slowed conduction caused by post operative myocardial edema. Catecholamine therapy which is a main stay of treatment during the post operative period can also lead to increased automaticity and shorten the refractory period to cause R on T phenomenon. This case highlights the importance of continuous telemetry monitoring, maintaining of high normal potassium and magnesium. Temporary pacing wires placement immediately in the post operative period also can help terminate Torsades and prevent deterioration. Early recognition enables timely management of R on T phenomenon to prevent progression to Torsades which can be very fatal leading to sudden cardiac death. This abstract is funded by: Self
Madine et al. (Fri,) conducted a case report in Post-CABG R-on-T phenomenon and Torsades de Pointes (n=1). Defibrillation, magnesium, lidocaine, potassium repletion, and amiodarone was evaluated. Post-CABG R-on-T phenomenon progressed to Torsades de Pointes and ventricular fibrillation in a 75-year-old woman, which was successfully terminated with defibrillation and medical therapy.