Patients:
Consecutive patients attending in sinus rhythm for evaluative diagnostic electrophysiologic studies for supraventricular tachycardia (SVT) were recruited. Exclusion criteria were absence of documented sinus rhythm, presence of permanent pacemaker or implantable cardioverter-defibrillator (ICD), lack of coronary sinus catheter utilization for any reason, a documented history of atrial fibrillation, lack of electroanatomic mapping system, or continued use of antiarrhythmic drugs within 5 half-lives before the procedure.
The patient cohort was divided into those with a history of documented AFL and controls. AFL patients were defined as subjects with a documented history of typical atrial flutter on 12-lead ECG. Control patients were defined as subjects with a history of SVT, the intended clinical target of the present ablation, but without history of documented AFL. The study protocol was reviewed and approved by Queen’s University Health Sciences and affiliated teaching hospital’s research ethics board.