Elusive cardiac dysrhythmia in high-risk syncope.

Emergency department presentations of syncope can vary from benign to life-threatening etiologies. Older patients are at increased risk of cardiac causes of syncope. Ventricular standstill is a rare phenomenon that can manifest as syncope and must be correctly identified and promptly treated to prevent sudden cardiac arrest. We report the case of a 70-year old man with dizziness and convulsive syncope whose initial ECG showed a right bundle branch block, but then developed ventricular standstill and intermittent high-grade AV block while still in the ED. He was transferred to the ICU and underwent pacemaker implantation. A high index of suspicion for dysrhythmias should be maintained for any patient presenting to the ED with high-risk syncope.