Irbesartan in Patients With Atrial Fibrillation
What are the effects of irbesartan on the risk of cardiovascular events and maintenance of sinus rhythm in patients with atrial fibrillation?
The investigators randomly assigned patients with a history of risk factors for stroke and a systolic blood pressure of at least 110 mm Hg to receive either irbesartan at a target dose of 300 mg once daily or double-blind placebo. These patients were already enrolled in one of two trials (of clopidogrel plus aspirin vs. aspirin alone or vs. oral anticoagulants). The first coprimary outcome was stroke, myocardial infarction, or death from vascular causes; the second was the composite outcome plus hospitalization for heart failure. The time to outcomes such as cardioversion or hospitalization for atrial fibrillation was assessed with the use of the Kaplan-Meier method, and differences between the study groups were compared with the use of the log-rank test.
A total of 9,016 patients were enrolled and followed for a mean of 4.1 years. The mean reduction in systolic blood pressure was 2.9 mm Hg greater in the irbesartan group than in the placebo group, and the mean reduction in diastolic blood pressure was 1.9 mm Hg greater. The first coprimary outcome occurred at a rate of 5.4% per 100 person-years in both groups (hazard ratio [HR] with irbesartan, 0.99; 95% confidence interval [CI], 0.91-1.08; p = 0.85). The second coprimary outcome occurred at a rate of 7.3% per 100 person-years among patients receiving irbesartan and 7.7% per 100 person-years among patients receiving placebo (HR, 0.94; 95% CI, 0.87-1.02; p = 0.12). The rates of first hospitalization for heart failure (a prespecified secondary outcome) were 2.7% per 100 person-years among patients receiving irbesartan and 3.2% per 100 person-years among patients receiving placebo (HR, 0.86; 95% CI, 0.76-0.98). Among patients who were in sinus rhythm at baseline, there was no benefit of irbesartan in preventing hospitalization for atrial fibrillation or atrial fibrillation recorded on 12-lead electrocardiography, nor was there a benefit in a subgroup that underwent transtelephonic monitoring. More patients in the irbesartan group than in the placebo group had symptomatic hypotension (127 vs. 64) and renal dysfunction (43 vs. 24).
The authors concluded that irbesartan did not reduce cardiovascular events in patients with atrial fibrillation.
The study suggests that among patients with atrial fibrillation, irbesartan does not reduce the risk of death from cardiovascular causes, stroke, or myocardial infarction or this composite outcome plus hospitalization for heart failure. Furthermore, among patients in sinus rhythm at randomization, there appears to be no effect on recurrence of atrial fibrillation. Based on this, angiotensin-receptor blockers such as irbesartan should not be routinely prescribed to patients with atrial fibrillation and well-controlled hypertension.
Keywords: Biphenyl Compounds, Myocardial Infarction, Risk Factors, Electrocardiography, Tetrazoles, Hospitalization
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