1:1 atrial-flutter. Prevalence and clinical characteristics.

UNLABELLED: Little is known about the epidemiology of 1:1 atrial flutter (AFL). Our objectives were to determine its prevalence and predisposing conditions.

METHODS: 1037 patients aged 16 to 93 years (mean 64±12) were consecutively referred for AFL ablation. 791 had heart disease (HD). Patients admitted with 1/1 AFL were collected. Patients were followed 3±3 years.

RESULTS: 1:1 AFL-related tachycardiomyopathy was found in 85 patients, 59 men (69%) with a mean age of 59±12 years. The prevalence was 8%. They were compared to 952 patients, 741 men (78%, 0.04), with a mean age of 65±12 years (0.002) without 1:1 AFL. Factors favoring 1:1 AFL was the absence of HD (35 vs 23%, 0.006), the history of AF (42 vs 30.5%)(0.025) and the use of class I antiarrhythmic drugs (34 vs 13%)(p<0.0001), while use of amiodarone or beta blockers was less frequent in patients with 1:1 AFL (5, 3.5%) than in patients without 1:1 AFL (25, 15%) (p<0.0001, 0.03). The failure of ablation (9.4 vs 11%), ablation-related complications (2.3 vs 1.4%), risk of subsequent atrial fibrillation (AF) (20 vs 24%), risk of AFL recurrences (19 vs 13%) and risk of cardiac death (5 vs 6%) were similar in patients with and without 1:1 AFL.

CONCLUSIONS: The prevalence of 1:1 AFL in patients admitted for AFL ablation was 8%. These patients were younger, had less frequent HD, had more frequent history of AF and received more frequently class I antiarrhythmic drugs than patients without 1:1 AFL. Their prognosis was similar to patients without 1:1 AFL.