The Subtle Pattern of Sinoatrial Wenckebach.

INTRODUCTION

Second-degree sinoatrial (SA) exit block type I, or SA Wenckebach, is a rare arrhythmia marked by progressively shortening P-P intervals followed by a dropped P wave and a noncompensatory pause, producing a grouped beating pattern on electrocardiogram (ECG).

CASE PRESENTATION: A 64-year-old male with multiple comorbidities presented after a mechanical fall with bradycardia. ECG revealed a new SA exit block type I. Echocardiography showed preserved ejection fraction and grade II diastolic dysfunction.

DISCUSSION: Nodal blockers were discontinued, and pacemaker implantation was deemed unnecessary. Recognizing SA exit block is important, as it can mimic atrioventricular block or sinus arrhythmia on ECG.