Clinical trials

In the past 2 years, a number of landmark clinical trials have been published which further our understanding and clinical management of patients with atrial fibrillation (AF). Two of the major goals in the treatment of this condition include reducing progression or recurrence of the arrhythmia and decreasing the risk of cardiovascular events, thereby improving quality of life and decreasing morbidity. Following on from a large body of evidence from preclinical studies, small clinical trials and meta-analyses suggesting that blockade of the renin–angiotensin system has beneficial effects on the pathophysiology of AF,1 two large multicentre, placebo-controlled, randomised trials were conducted to determine the effects of angiotensin II receptor blockers (ARBs) on AF.

The first of these trials, published in 2009, tested the hypothesis that the ARB valsartan could reduce the recurrence of AF in patients with underlying cardiovascular disease, diabetes or left atrial enlargement and a history of documented AF, in addition to established treatments.2 A total of 1442 patients were enrolled into the study—722 assigned to the valsartan group (target dose 320 mg) and 720 to the placebo group. The investigators found that treatment with valsartan had no significant effect on AF recurrence (AF recurrence 51.4% in the valsartan group and 52.1% in the placebo group, p=0.73) over a relatively short follow-up period of 1 year.

The second large ARB randomised controlled trial (RCT) published this year evaluated whether irbesartan would reduce the risk of cardiovascular events in patients with AF.3 Patients with a history of risk factors for stroke and a systolic blood pressure of at least 110 mm Hg were randomly assigned to receive either irbesartan (target dose of 300 mg once daily) or placebo. Patients for this study were already enrolled in one of two other AF trials looking at clopidogrel plus aspirin versus aspirin alone or versus oral …