THROMBOEMBOLISM IN CHRONIC ATRIAL-FLUTTER - IS THE RISK UNDERESTIMATED

Objectives. We sought to evaluate the risk of thromboembolic events in the presence of chronic atrial Butter and to determine the impact of anticoagulation therapy, if any, on this risk. Background. Thromboembo lic events are thought to be rare after cardioversion of atrial Butter . Methods. This study was a retrospective analysis of 110 consecutive patients referred to the electrophysiology laboratory for cardioversio n of chronic atrial Butter from 1986 to 1996. Atrial flutter,vas prese nt for at least 6 months. Of the 110 patients reviewed, 100 had adequa te information available regarding the effectiveness of anticoagulatio n (mean age 64 years, range 27 to 86; 75 men, 25 women; mean left vent ricular ejection fraction 42%), Results. Thirteen patients (13%) had a thromboembolic event, Of these, seven were attributable to causes oth er than atrial flutter. In the remaining six patients (6%), thromboemb olic events occurred during a rhythm of atrial Butter or after cardiov ersion to sinus rhythm, Other causes of thromboembolism were excluded. Effective anticoagulation was associated with a decreased risk of thr omboembolism (p = 0.026). Conclusions. Patients with chronic atrial Bu tter are at an increased risk of thromboembolic events. Effective anti coagulation may decrease this risk. (C) 1997 by the American College o f Cardiology.