Introduction: P-wave dispersion (PWD) has been shown to be a non-invasive electrocardiographic predictor for development of atrial fibrillation (AF). Thus, it may be possible to attenuate AF risk through improvement of PWD. In this study, we compared the effects of an angiotensin-converting enzyme (ACE) inhibitor, quinapril, and an angiotensin receptor blocker (ARB), irbesartan, on PWD. 

Methods: A total of 38 newly diagnosed hypertensive patients were enrolled in the study. The patients were randomly assigned to receive treatment with either irbesartan (150-300 mg) or quinapril (20-40 mg). P-wave durations and PWD were measured at baseline and after 6 and 12 months of treatment. Echocardiographic examinations were performed at baseline and after 12 months of treatment. 

Results: Both drugs significantly reduced blood pressure to a similar degree (P < 0.001). Deceleration time (both P < 0.001) and isovolumetric relaxation time (both P=0.007) were also significantly reduced, whereas there was no significant change in the early diastolic flow/atrial contraction signal ratio. Both irbesartan and quinapril significantly decreased maximum P-wave duration (Pmax) (P < 0.001 and P=0.002, respectively) and PWD (from 68.0 +/- 22.1 to 41.0 +/- 25.1 msec for irbesartan, and from 70.5 +/- 20.4 to 46.6 +/- 13.3 msec for quinapril; both P < 0.001). Baseline and follow-up blood pressure, heart rate, echocardiographic findings, and P-wave values were not significantly different between the irbesartan and quinapril groups. No patient developed AF during follow-up. There was no significant correlation between PWD and blood pressure or diastolic function parameters. 

Conclusion: Antihypertensive treatment with either irbesartan or quinapril is associated with significant reductions in Pmax and PWD.