Effect of atenolol on symptomatic ventricular arrhythmia without structural heart disease: a randomized placebo-controlled study.

Background: Ventricular arrhythmia (VA) from the right ventricular outflow tract (RVOT) is a common problem. Symptomatic patients are usually treated with beta-blockers. There is little data on the systematic evaluation of the efficacy of beta-blocker. We determine the efficacy of atenolol in the treatment of symtomatic VA from RVOT compared with placebo.

Methods And Results: This was a randomized, double-blinded, placebo-controlled study. We prospectively studied 52 consecutive patients with symptomatic VA. Severity of symptoms, 24-hour ambulatory monitoring (AECG) and quality of life (QOL) were assessed at baseline and 1 month after atenolol. Exercise testing was performed at baseline. Average premature ventricular complex (PVC) count at baseline was 21,407 +/- 1740 beats per 24 hours, and 19% had ventricular tachycardia as measured by AECG. Results of this study showed that atenolol significantly decreased symptom frequency (P =.03), PVC count (P =.001) and average heart rate (P <.001) measured by AECG, whereas placebo significantly decreased symptom frequency (P =.002) but had no effect on PVC count (P =.78) or average heart rate (P =.44). Neither atenolol nor placebo had an effect on QOL.

Conclusions: Atenolol improves symptoms and decreases PVC count from ambulatory monitoring. Placebo improved symptoms to the same extent as atenolol but had no effect on severity of VA. This might be the so-called placebo effect, which is a concern when treating patients or doing research on the effects of a drug.