Bursts Beneath the Surface: Using the Electrocardiogram as a Blueprint to Arrhythmogenesis

The surface electrocardiogram (ECG) can provide many clues to a patient’s underlying medical condition or tendency for arrhythmogenesis. An 80-year-old man with severe aortic stenosis and a prior an implantable cardioverter-defibrillator (ICD) for advanced heart block presented with burping, chest discomfort and intermittent pounding sensations. His ECG showed atrial fibrillation with intermittent ventricular pacing at 60 bpm characterized by irregularly irregular rhythm, absent P waves, narrow intrinsic QRS complexes alternating with wide-paced beats (left bundle branch block [LBBB] morphology, superior axis) and visible pacing spikes. Device interrogation revealed ventricular tachycardia (VT) storm with multiple appropriate ICD shocks explaining his pounding sensations. This case report highlights two key teaching points: recognizing atrial fibrillation during ventricular pacing—a frequently missed diagnosis affecting nearly half of pacemaker patients with pacemakers—and managing VT storm to reduce shock burden. After device reprogramming and antiarrhythmic adjustment, the patient became asymptomatic. Keywords Electrocardiogram, arrhythmia, atrial fibrillation, aortic stenosis, cardiac pacing