Diagnostic superiority of continuous-loop electrocardiographic recording over other testing in a patient with...

Dysrhythmic causes of syncope may elude diagnosis in postinfarction patients despite elaborate testing, including electrophysiologic study. For a correct diagnosis, capture of cardiac rhythm during patient's typical symptoms is crucial. This report describes a patient with coronary artery disease and decreased left ventricular ejection fraction who experienced recurrent syncopal episodes without obvious precipitating factors. The 12-lead electrocardiogram showed left bundle-branch block indicating a possible conduction abnormality as the underlying cause of syncope. Twenty-four-h Holter monitoring exhibited no sinus rhythm or conduction disturbances but revealed a nonsustained run of ventricular tachycardia. Findings at electrophysiologic testing led to a presumptive diagnosis of tachyarrhythmic cause of syncope; however, the correct diagnosis was only made with use of a loop monitor which documented a 15-s sinus pause during a syncopal episode.