P3474Relationship between international normalized ratio variability, quality of anticoagulation control and outcomes in patients with atrial fibrillation: an AFFIRM post-hoc analysis

Abstract

Abstract Introduction Quality of anticoagulation control is essential to ensure better clinical outcomes in patients with atrial fibrillation (AF). Time in therapeutic range (TTR) is recommended as a measure of the quality of anticoagulation control. The International normalized ratio (INR) variability has been suggested as an alternative index, even though large independent validations for this index are still lacking. Purpose To provide validation of clinical usefulness of INR variability as a measure of the quality of anticoagulation control in a large cohort of AF patients. Methods Data from the Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) trial were analysed. INR variability was defined as the standard deviation (SD) of mean INR values [INR-SD] recorded throughout the follow-up observation for each patient. All patients with available INR values were included in the analysis. Stroke, major bleeding, cardiovascular (CV) death and all-cause death were study outcomes. Results Among the original 4060 patients, a total of 3185 (78.4%) were available for analysis. Mean (SD) INR-SD was 0.58 (0.25). According to INR-SD patients were categorized into four quartiles. Mean (SD) CHA2DS2-VASc score was increased (p=0.040), with no difference in proportions of CHA2DS2-VASc ≥2 (p=0.582) between the subgroups. A significant inverse correlation was found between INR-SD and TTR (Spearman's Rho: −0.536, p<0.001). Continuous INR-SD, after multiple adjustments, was inversely associated with TTR (standardized beta: −0.451, p<0.001) and directly associated with SAMe-TT2R2score (standardized beta: 0.084, p<0.001). A fully adjusted Cox multivariate regression analysis found that INR-SD was directly associated with increased risk of stroke, major bleeding and all-cause death (Table). An INR-SD ≥0.85 was directly associated with all the study outcomes, on multivariate analysis (Table). Cox Regression Analysis INR-SD INR-SD ≥0.85 HR (95% CI) HR (95%) Stroke 2.52 (1.34–4.67) 1.62 (1.00–2.63) Major Bleeding 2.43 (1.49–3.96) 1.61 (1.10–2.36) CV Death 1.50 (0.87–2.59) 1.54 (1.07–2.24) All-Cause Death 1.79 (1.21–2.66) 1.55 (1.17–2.05) CI = Confidence Interval; CV = Cardiovascular; HR = Hazard Ratio; INR-SD = International Normalized Ratio Standard Deviation. Conclusions INR variability, expressed as INR-SD, was significantly correlated and associated with TTR. Both continuous INR-SD and INR-SD ≥0.85 were significantly associated with a higher risk of all study adverse outcomes. Acknowledgement/Funding None