Prognosis and guideline-adherent antithrombotic treatment in patients with atrial fibrillation and atrial flutter: implications of undertreatment and overtreatment in real-life clinical practice; the Loire Valley Atrial Fibrillation Project.

BACKGROUND: In patients with atrial fibrillation (AF), adherence to guidelines for antithrombotic treatment is poorly followed, and undertreatment (or nonadherence with guidelines) is associated with a worse prognosis. The study objective was to evaluate whether this was also the case in a large contemporary series of unselected patients with AF in real-world clinical practice.

METHODS: All patients with AF or atrial flutter seen in our institution between 2000 and 2007 were identified in a database and followed up for mortality and stroke. Antithrombotic guideline adherence was assessed according to the 2006 American College of Cardiology/American Heart Association/European Society of Cardiology guidelines.

RESULTS: We reviewed outcomes in 3,646 consecutive patients with AF or atrial flutter (aged 71 ± 14 years; mean CHADS(2) [congestive heart failure, hypertension, aged ≥ 75 years, diabetes mellitus, prior stroke or transient ischemic attack] score, 1.5 ± 1.1). Antithrombotic treatment was in agreement with the guidelines in 53% of patients, whereas 31% were classified as undertreated and 16% as overtreated. Among other parameters, nonpermanent AF and atrial flutter were independently associated with an increased risk of undertreatment. After a follow-up of 953 ± 767 days (median, 771 days; interquartile range, 1,286 days), guideline adherence was associated with a lower risk of adverse events (death from all causes or stroke) compared with undertreatment (relative risk, 0.47; 95% CI, 0.40-0.55; P < .0001). Overtreatment was associated with a lower risk of adverse events compared with the guideline-adherent population (relative risk, 0.40; 95% CI, 0.28-0.58; P < .0001). Factors independently associated with increased risk of mortality or stroke were antithrombotic undertreatment, older age, heart failure, renal failure, diabetes, male sex, and previous history of stroke.

CONCLUSIONS: Guideline nonadherence and undertreatment with antithrombotic agents in unselected real-world patients with AF or atrial flutter are independently associated with a high risk of stroke and mortality.