The patient is an 81-year-old woman with a history of hypertension, obesity, obstructive sleep apnea, and atrial fibrillation ablation five years ago. She has noted acute increase in fatigue and exercise intolerance and presented to the emergency room. The following ECG is performed:
The ECG shows which of the following?
The correct answer is: A. Atrial flutter.
The ECG shows a regular narrow complex tachycardia with a heart rate of 125/minute. The QRS axis is normal. The R wave progression is blunted but within normal limits. An atrial depolarization is seen on the descending limb of the T wave. The P wave is upright in lead II and prominently upright in V1. Inspection of the terminal QRS shows a second atrial depolarization, giving a pseudo-R wave in V1 and a J wave in leads II, III and aVF. The rhythm is showing atrial flutter with 2:1 AV block. This atrial flutter is atypical and most likely located in the left atrium. In a retrospective study of 607 patients who underwent atrial fibrillation ablation, multivariable analysis showed that persistent atrial fibrillation, linear ablation lesions, and left atrial volume index were highly associated with high incidence of atypical atrial flutter.1
Ipek EG, Marine J, Yang E, et al. Predictors and incidence of atrial flutter after catheter ablation of atrial fibrillation. Am J Cardiol 2019;124:1690-6.