Risk of Ischemic Stroke in High Risk Atrial Fibrillation Patients during Periods of Warfarin Discontinuation for Surgical Procedures.

IMPORTANCE

The risk of ischemic stroke during periods of warfarin discontinuation for surgical procedures is recognized but not well characterized.

OBJECTIVE

The study aimed to quantitate the risk of ischemic stroke associated with high risk atrial fibrillation during periods of warfarin discontinuation.

DESIGN, SETTING AND

PARTICIPANTS

A cohort of 4,060 patients (mean follow-up period of 3.5 ± 1.3 years) were randomized into the Atrial Fibrillation Follow-Up Investigation of Rhythm Management study. Patients enrolled in the study had atrial fibrillation plus at least one other risk factor for stroke or death: age ≥65 years', systemic hypertension, diabetes mellitus, congestive heart failure, transient ischemic attack, prior stroke, left atrium >50 mm, left ventricular fractional shortening <25% or left ventricular ejection fraction <40%.

EXPOSURE: Warfarin discontinuation for procedure.

MAIN OUTCOME AND MEASURES: The association of warfarin discontinuation with the incidence of ischemic stroke using pooled repeated measures and Cox proportional hazards analyses during follow-up after adjusting for age, gender, obesity, diabetes mellitus, hypercholesterolemia, cigarette smoking and study period.

RESULTS

Warfarin discontinuation for procedure occurred in 265 (0.4%) of the 71,355 person observations. Compared with those without warfarin discontinuation, the rate of ischemic stroke was higher among participants with surgery-related warfarin discontinuation (1.1% of 265 person observations vs. 0.2% of 71,090 person observations, p = 0.001). Warfarin discontinuation was associated with an increased risk for ischemic stroke (relative risk 5.8; 95% CI 1.8-18.4) after adjusting for potential confounders. The population-attributable risk associated with surgery-related warfarin discontinuation was estimated to be 23.1% (95% CI 15.2-30.9%) for ischemic stroke.

CONCLUSIONS AND RELEVANCE: The 6-fold higher risk of ischemic stroke associated with discontinuation of warfarin for surgical procedures must be recognized in high risk atrial fibrillation patients and considered in the risk-benefit analysis of any procedure.