Ischemic Complications in Nonvalvular Atrial Fibrillation Patients Despite Warfarin Therapy

Abstract number: P1026

Poli D, Antonucci E, Cecchi E, Mannini L, Sestini I, Sticchi E, Falciani M, Abbate R, Gensini GF, Prisco D

Oral anticoagulant treatment (OAT) is the cornerstone for stroke prevention in patients with atrial fibrillation (AF). The aims of our study were: (1) to evaluate the efficacy of OAT in the prevention of cardiovascular complications in AF patients; and (2) to evaluate if comorbidity and cardiovascular risk factors may play a role in unsuccessful OAT. We studied 303 AF patients on OAT (186M, 117F, mean age 72.9 ± 8.2, follow-up 571 patient-years). During follow-up, 20 patients (12M, 8F) had thrombotic complications (rate 3.5/100 patient-years): 7 TIA, 8 stroke, 4 peripheral embolisms, 1 myocardial infarction. Time spent within, above and below the intended therapeutic range was 71%, 13% and 16% in AF patients without thrombotic events and 64%, 14% and 22% in AF patients with thrombotic events. The mean INR related to the thrombotic event was 1.9 ± 0.5. Univariate analysis showed no correlation between the occurrence of thrombotic event despite OAT and sex, the presence of either hypertension, coronary artery disease, diabetes, hypercholesterolemia, peripheral artery disease, or hearth failure respectively. Hyperhomocysteinemia was more frequent, in patients with thrombotic events than in those without, but this difference was not statistically significant (P= 0.07). On the contrary, a significant correlation was found between a positive history of a previous thrombotic event and the recurrence of thrombotic event and [OR 8 (2.3–28.0), P= 0.001]. A multivariate analysis adjusted for the other above-mentioned variables, confirmed the history for a previous thrombotic event as a strong risk factor for unsuccessful OAT [OR 6.8 (1.8–24.6), P= 0.003]. Moreover, these patients showed a worse OAT control, with longer time spent below the intended INR. In conclusion, OAT is highly efficacious for the prevention of cardiovascular events. Special efforts are needed to maintain INR within the therapeutic range, specially in patients with previous thrombotic complications for whom closer INR controls may be indicated.