ARISTOTLE: Blood Pressure Adversely Affects Stroke Risk in A-fib Patients

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Poorly controlled hypertension raises the risk of stroke or systemic embolism by 50% in patients with atrial fibrillation (A-fib) regardless of whether they receive warfarin or the new anticoagulant apixaban, according to a poster presented March 29, 2014, at the American College of Cardiology/i2 Scientific Session in Washington, DC.

Meena Rao, MD, MPH, of Duke University Medical Center (Durham, NC), and colleagues conducted a prespecified subanalysis of the ARISTOTLE trial, which randomized 18,201 patients with A-fib and at least 1 additional risk factor to either apixaban (5 mg twice daily or 2.5 mg twice daily) or dose-adjusted warfarin (target INR range of 2.0-3.0). Originally published in the New England Journal of Medicine in 2011, the study showed that apixaban reduced the relative risk of stroke/systemic embolism by 21%.

In all, 15,916 of trial participants (87.5%) had a history of hypertension requiring treatment.

Hypertension Matters at Baseline and During Antithrombotic Therapy

Unadjusted risk of stroke or systemic embolism and of hemorrhagic stroke in particular tended to be higher for patients with a history of hypertension as well as for those who at baseline had poorly controlled hypertension (systolic BP > 140 mm Hg and/or diastolic BP > 90 mm Hg), though the differences did not reach significance. Both groups had a significantly lower risk of death.

Half of patients had poorly controlled hypertension at some point during the trial. On Cox proportional analysis, this was associated with increased risks of stroke or systemic embolism, major or clinically relevant non-major bleeding, or any bleeding (table 1).

Table 1. Risk of Outcomes: Poorly Controlled vs No Hypertension

In addition, the ability of apixaban to better prevent stroke or systemic embolism compared with warfarin was consistent among patients with and without a history of hypertension (P for interaction = 0.27), blood pressure control at baseline (P for interaction = 0.43), and blood pressure control during the trial (P for interaction = 0.97).

“These data highlight the critical importance of blood pressure control in addition to anticoagulation in helping to lower the risk of stroke in patients with atrial fibrillation,” Dr. Rao commented in a press release.

Study Details:

Patients with a history of hypertension had higher CHA₂DS₂-VASc scores but similar HAS-BLED scores compared with those without prior hypertension. There also were numerous differences in baseline characteristics with the hypertension group more likely to have diabetes and CAD yet less likely to have impaired renal function or heart failure.

Source:Rao M, Halvorsen S, Wojdyla D, et al. Poorly controlled blood pressure is independently associated with a 50% higher risk of stroke or systemic embolism in patients with atrial fibrillation: results from the ARISTOTLE trial. Presented at: American College of Cardiology/i2 Scientific Session; March 29, 2014; Washington, DC.

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