Christopher C. Nessel

BACKGROUND: The use of warfarin reduces the rate of ischemic stroke in patients with atrial fibrillation but requires frequent monitoring and dose adjustment. Rivaroxaban, an oral factor Xa inhibitor, may provide more consistent and predictable anticoagulation than warfarin. METHODS: In a double-blind trial, we randomly assigned 14,264 patients with nonvalvular atrial fibrillation who were at increased risk for stroke to receive either rivaroxaban (at a daily dose of 20 mg) or dose-adjusted warfarin. The per-protocol, as-treated primary analysis was designed to determine whether rivaroxaban was noninferior to warfarin for the primary end point of stroke or systemic embolism. RESULTS: In the primary analysis, the primary end point occurred in 188 patients in the rivaroxaban group (1.7% per year) and in 241 in the warfarin group (2.2% per year) (hazard ratio in the rivaroxaban group, 0.79; 95% confidence interval [CI], 0.66 to 0.96; P<0.001 for noninferiority). In the intention-to-treat analysis, the primary end point occurred in 269 patients in the rivaroxaban group (2.1% per year) and in 306 patients in the warfarin group (2.4% per year) (hazard ratio, 0.88; 95% CI, 0.74 to 1.03; P<0.001 for noninferiority; P=0.12 for superiority). Major and nonmajor clinically relevant bleeding occurred in 1475 patients in the rivaroxaban group (14.9% per year) and in 1449 in the warfarin group (14.5% per year) (hazard ratio, 1.03; 95% CI, 0.96 to 1.11; P=0.44), with significant reductions in intracranial hemorrhage (0.5% vs. 0.7%, P=0.02) and fatal bleeding (0.2% vs. 0.5%, P=0.003) in the rivaroxaban group. CONCLUSIONS: In patients with atrial fibrillation, rivaroxaban was noninferior to warfarin for the prevention of stroke or systemic embolism. There was no significant between-group difference in the risk of major bleeding, although intracranial and fatal bleeding occurred less frequently in the rivaroxaban group. (Funded by Johnson & Johnson and Bayer; ROCKET AF ClinicalTrials.gov number, NCT00403767.).

AIMS: Patients with non-valvular atrial fibrillation (AF) and renal insufficiency are at increased risk for ischaemic stroke and bleeding during anticoagulation. Rivaroxaban, an oral, direct factor Xa inhibitor metabolized predominantly by the liver, preserves the benefit of warfarin for stroke prevention while causing fewer intracranial and fatal haemorrhages. METHODS AND RESULTS: We randomized 14 264 patients with AF in a double-blind trial to rivaroxaban 20 mg/day [15 mg/day if creatinine clearance (CrCl) 30-49 mL/min] or dose-adjusted warfarin (target international normalized ratio 2.0-3.0). Compared with patients with CrCl >50 mL/min (mean age 73 years), the 2950 (20.7%) patients with CrCl 30-49 mL/min were older (79 years) and had higher event rates irrespective of study treatment. Among those with CrCl 30-49 mL/min, the primary endpoint of stroke or systemic embolism occurred in 2.32 per 100 patient-years with rivaroxaban 15 mg/day vs. 2.77 per 100 patient-years with warfarin [hazard ratio (HR) 0.84; 95% confidence interval (CI) 0.57-1.23] in the per-protocol population. Intention-to-treat analysis yielded similar results (HR 0.86; 95% CI 0.63-1.17) to the per-protocol results. Rates of the principal safety endpoint (major and clinically relevant non-major bleeding: 17.82 vs. 18.28 per 100 patient-years; P = 0.76) and intracranial bleeding (0.71 vs. 0.88 per 100 patient-years; P = 0.54) were similar with rivaroxaban or warfarin. Fatal bleeding (0.28 vs. 0.74% per 100 patient-years; P = 0.047) occurred less often with rivaroxaban. CONCLUSION: Patients with AF and moderate renal insufficiency have higher rates of stroke and bleeding than those with normal renal function. There was no evidence of heterogeneity in treatment effect across dosing groups. Dose adjustment in ROCKET-AF yielded results consistent with the overall trial in comparison with dose-adjusted warfarin.

BACKGROUND: We sought to define the factors associated with the occurrence of stroke and systemic embolism in a large, international atrial fibrillation (AF) trial. METHODS AND RESULTS: In ROCKET AF (Rivaroxaban Once-daily, oral, direct factor Xa inhibition Compared with vitamin K antagonism for prevention of stroke and Embolism Trial in Atrial Fibrillation), 14 264 patients with nonvalvular AF and creatinine clearance ≥30 mL/min were randomized to rivaroxaban or dose-adjusted warfarin. Cox proportional hazards modeling was used to identify factors at randomization independently associated with the occurrence of stroke or non-central nervous system embolism based on intention-to-treat analysis. A risk score was developed in ROCKET AF and validated in ATRIA (AnTicoagulation and Risk factors In Atrial fibrillation), an independent AF patient cohort. Over a median follow-up of 1.94 years, 575 patients (4.0%) experienced primary end-point events. Reduced creatinine clearance was a strong, independent predictor of stroke and systemic embolism, second only to prior stroke or transient ischemic attack. Additional factors associated with stroke and systemic embolism included elevated diastolic blood pressure and heart rate, as well as vascular disease of the heart and limbs (C-index 0.635). A model that included creatinine clearance (R(2)CHADS(2)) improved net reclassification index by 6.2% compared with CHA(2)DS(2)VASc (C statistic=0.578) and by 8.2% compared with CHADS(2) (C statistic=0.575). The inclusion of creatinine clearance <60 mL/min and prior stroke or transient ischemic attack in a model with no other covariates led to a C statistic of 0.590.Validation of R(2)CHADS(2) in an external, separate population improved net reclassification index by 17.4% (95% confidence interval, 12.1%-22.5%) relative to CHADS(2). CONCLUSIONS: In patients with nonvalvular AF at moderate to high risk of stroke, impaired renal function is a potent predictor of stroke and systemic embolism. Stroke risk stratification in patients with AF should include renal function. CLINICAL TRIAL REGISTRATION: URL: http://www.ClinicalTrials.gov. Unique identifier: NCT00403767.

BACKGROUND: Nonvalvular atrial fibrillation is common in elderly patients, who face an elevated risk of stroke but difficulty sustaining warfarin treatment. The oral factor Xa inhibitor rivaroxaban was noninferior to warfarin in the Rivaroxaban Once Daily, Oral, Direct Factor Xa Inhibition Compared With Vitamin K Antagonism for Prevention of Stroke and Embolism Trial in Atrial Fibrillation (ROCKET AF). This prespecified secondary analysis compares outcomes in older and younger patients. METHODS AND RESULTS: There were 6229 patients (44%) aged ≥75 years with atrial fibrillation and ≥2 stroke risk factors randomized to warfarin (target international normalized ratio=2.0-3.0) or rivaroxaban (20 mg daily; 15 mg if creatinine clearance <50 mL/min), double blind. The primary end point was stroke and systemic embolism by intention to treat. Over 10 866 patient-years, older participants had more primary events (2.57% versus 2.05%/100 patient-years; P=0.0068) and major bleeding (4.63% versus 2.74%/100 patient-years; P<0.0001). Stroke/systemic embolism rates were consistent among older (2.29% rivaroxaban versus 2.85% warfarin per 100 patient-years; hazard ratio=0.80; 95% confidence interval, 0.63-1.02) and younger patients (2.00% versus 2.10%/100 patient-years; hazard ratio=0.95; 95% confidence interval, 0.76-1.19; interaction P=0.313), as were major bleeding rates (≥75 years: 4.86% rivaroxaban versus 4.40% warfarin per 100 patient-years; hazard ratio=1.11; 95% confidence interval, 0.92-1.34; <75 years: 2.69% versus 2.79%/100 patient-years; hazard ratio=0.96; 95% confidence interval, 0.78-1.19; interaction P=0.336). Hemorrhagic stroke rates were similar in both age groups; there was no interaction between age and rivaroxaban response. CONCLUSIONS: Elderly patients had higher stroke and major bleeding rates than younger patients, but the efficacy and safety of rivaroxaban relative to warfarin did not differ with age, supporting rivaroxaban as an alternative for the elderly.

AIM: Anticoagulation prophylaxis for stroke is recommended for at-risk patients with either persistent or paroxysmal atrial fibrillation (AF). We compared outcomes in patients with persistent vs. paroxysmal AF receiving oral anticoagulation. METHODS AND RESULTS: Patients randomized in the Rivaroxaban Once Daily Oral Direct Factor Xa Inhibition Compared With Vitamin K Antagonism for Prevention of Stroke and Embolism Trial in Atrial Fibrillation (ROCKET-AF) trial (n = 14 264) were grouped by baseline AF category: paroxysmal or persistent. Multivariable adjustment was performed to compare thrombo-embolic events, bleeding, and death between groups, in high-risk subgroups, and across treatment assignment (rivaroxaban or warfarin). Of 14 062 patients, 11 548 (82%) had persistent AF and 2514 (18%) had paroxysmal AF. Patients with persistent AF were marginally older (73 vs. 72, P = 0.03), less likely female (39 vs. 45%, P < 0.0001), and more likely to have previously used vitamin K antagonists (64 vs. 56%, P < 0.0001) compared with patients with paroxysmal AF. In patients randomized to warfarin, time in therapeutic range was similar (58 vs. 57%, P = 0.94). Patients with persistent AF had higher adjusted rates of stroke or systemic embolism (2.18 vs. 1.73 events per 100-patient-years, P = 0.048) and all-cause mortality (4.78 vs. 3.52, P = 0.006). Rates of major bleeding were similar (3.55 vs. 3.31, P = 0.77). Rates of stroke or systemic embolism in both types of AF did not differ by treatment assignment (rivaroxaban vs. warfarin, Pinteraction = 0.6). CONCLUSION: In patients with AF at moderate-to-high risk of stroke receiving anticoagulation, those with persistent AF have a higher risk of thrombo-embolic events and worse survival compared with paroxysmal AF.