Long-term outcomes in patients with ablation of clockwise and counterclockwise forms of typical atrial flutter

Background The atrial flutter of common type, with more frequent typical counterclockwise form, may occasionally present with clockwise form. The latter might be induced by clockwise functional block within cavotricuspid isthmus (CTI) of a premature atrial complex originating from the right atrium. Purpose As physiopathology might differ, we sought to compare long-term outcomes in patients who underwent CTI radiofrequency ablation for atrial flutter according to the electrical activation (clockwise or counterclockwise) at baseline. Methods All patients who underwent CTI radiofrequency ablation between 2000 and 2010 in the cardiology department of a four-hospital institution were included for analysis. Association with atrial fibrillation (supposed to be more frequently seen in case of left atrial origin of the arrhythmia), all-cause mortality, thromboembolic events, and atrial fibrillation occurrence were compared between patients with clockwise (group A) and counterclockwise (group B) CTI-dependant flutter. Results There was no significant difference at baseline (age, sex, heart failure, medication, hypertension, diabetes and stroke) between patients in group A ( n  = 41) and B ( n  = 831). Concomitant atrial fibrillation (AF) was present in 43% of patients in group A and 37% of patients in group B ( P  = 0.39). Deaths ( n  = 38), stroke/thromboembolic events ( n  = 30) and evolution to permanent AF ( n  = 53) were recorded after a follow-up of 826 ± 1024 days. There was no significant difference between both groups for occurrence of death of any cause (hazard ratio 1.31, 95%CI 0.53–3.23 in group A compared to group B, P  = 0.55), stroke and thromboembolic events (hazard ratio 2.17, 95%CI 0.65–7.14, P  = 0.20) and evolution to permanent AF (hazard ratio 2.27, 95%CI 0.78–6.25, P  = 0.13). Conclusion Despite very different prevalence rates, clockwise and counterclockwise forms of CTI dependent atrial flutter occur in similar populations and seem associated with relatively similar outcomes.