EKG Trivia

A 58-year-old woman with a history of atrial flutter and atrial fibrillation presented with presyncope. Her initial EKG revealed a heart rate in the 170s but after treatment with beta blockers and amiodarone, her heart rate improved to 97 with the EKG below.

What is the EKG finding?
Sinus tachycardia
Atrial tachycardia
Atrial fibrillation
Ventricular tachycardia
Atrial tachycardia
Notice the downgoing P-waves in lead I, which suggest that the source of the P-waves cannot be the sinus node. The rhythm is regular, which means this cannot be atrial fibrillation. The narrow QRS complexes suggest that the rhythm is supraventricular. This patient had atrial tachycardia with a 2:1 AV block, with a ventricular rate of 97 and atrial rate of 194.

Cardiology was consulted. Because the patient had recently undergone ablation, the patient was not felt to be a candidate for further ablation, as atrial tachyarrhythmias happen relatively commonly within the first 8 weeks after an atrial ablation.

With continuation of the amiodarone drip, the patient converted to normal sinus rhythm within 24 hours. She was discharged on oral amiodarone with cardiology follow-up.