But an accompanying editorial warns that the findings are not definitive and should not be used to guide clinical practice.
Atrial fibrillation is a well known risk factor for thromboembolism, and patients with this arrhythmia are usually treated with oral anticoagulants. While catheter ablation is “a promising cure” for atrial fibrillation, whether it could also free patients from the need for anticoagulation has not been definitively established, according to the report in the February 23rd Journal of the American College of Cardiology.
In a retrospective study, Dr. Antonio Raviele, from Dell’Angelo Hospital, Mestre-Venezia, Italy and colleagues in the U.S. and France analyzed data on 2692 patients who stopped oral anticoagulation 3 to 6 months after ablation and 663 who continued to take the drugs.
Each patient’s risk of thromboembolism was calculated using the CHADS2 scoring system, in which patients are assigned one point for each of the following: congestive heart failure, hypertension, age 75 or older, diabetes, and history of stroke or transient ischemic attack. Scores of 0, 1, and 2 or higher indicated low, moderate, and high risk for thromboembolism, respectively.
In the off-anticoagulation group, 1622 had a CHADS2 score of 0, 723 had a score of 1, and 347 had a score of 2 or higher. The corresponding numbers in the on-anticoagulation group were 155, 261, and 247.
At a mean follow-up of roughly 26 months, 2 (0.07%) patients in the off-anticoagulation group and 3 (0.45%) in the on-anticoagulation group had strokes (p = 0.06). No high-risk patient in the off-anticoagulation group had a stroke.
No other thromboembolic events occurred in either group, the report indicates.
Subjects who continued anticoagulation were more likely to have a major hemorrhage than those who stopped: 2% vs. 0.04% (p < 0.0001).
“This was not a randomized prospective study, but rather a summary of a 5-center experience,” the researchers write. “To date, however, it is the observational study with the largest set of case records.”
To confirm their findings, they add, randomized trials will need to include more than 3,000 patients at high risk for thromboembolism.
In an accompanying editorial, Dr. Ivan Cakulev and Dr. Albert L. Waldo, from University Hospitals Case Medical Center, Cleveland, emphasize the need for randomized trial data.
“Until we have prospective, randomized clinical trials that can help guide us in providing anticoagulation therapy for our patients,” warfarin should not be stopped, they write.
J Am Coll Cardiol 2010;55:735-746.