0370: Effect of smoking on comparative efficacy of antithrombotic therapy in patients with atrial fibrillation. A community based cohort study

Smoking is incorporated in a simple score (SAMe-TT2R2) that can predict poor INR control in patients with atrial fibrillation (AF) treated with vitamin K antagonists (VKA). Moreover, the clinical benefit of clopidogrel in reducing myocardial infarction and stroke in randomized clinical trials of antiplatelet drugs (APD) was seen primarily in smokers, with little benefit in nonsmokers. We made the hypothesis that active smoking may differently influence 1) the risk of stroke and 2) the risk of bleeding in AF patients treated with VKA or with APD. Methods We examined the clinical course of 7.948 consecutive patients with AF and/or atrial flutter seen between 2000-2010. The outcomes in patients with active smoking were compared with those in other patients. Results Among 7.948 patients with AF (age 71±15 years), 1034 (13%) had active smoking. APD was prescribed on an individual basis for 2761 patients (35%) and VKA for 4534 (57%). During a follow-up of 929±1082 days, 631 strokes/thromboembolic events, 707 severe bleedings and 248 major BARC bleedings were recorded. Smoking was not independently associated with a higher risk of stroke in these AF patients (relative risk=0.94, 95% CI 0.75-1.18, p=0.62). By contrast, after adjustment on age, CHADS2 score, HASBLED bleeding risk score, VKA use and APD use, smoking was independently associated with a worse prognosis for the risk of severe bleeding (relative risk=1.23, 95% CI 1,02- 1,50, p=0.03) and for the risk of major BARC bleeding (relative risk=1.40, 95% CI 1.03-1.91, p=0.03). Smoking was independently associated with a higher risk of bleeding in patients treated with VKA (relative risk= 1.32, 95% CI 1.04-1.66. p=0.02) whilst this association did not reach significance in patients treated with APD (relative risk=1.31, 95% CI 0.97-1.76. p=0.07). Conclusion In AF, there was a higher risk of bleeding in smokers, mainly in those treated with VKA