Effects of n-3 fatty acids from fish on premature ventricular complexes and heart rate in patients.

A large body of evidence suggests that n-3 fatty acids from fish prevent fatal heart disease. They may be an effective and safe alternative to drug treatment for reducing the risk of arrhythmia and sudden cardiac death. In this study, we investigated the effect of n-3 fatty acids on heart rate and premature ventricular complexes, a common form of arrhythmia that may trigger life-threatening arrhythmia. Patients (n = 84) with at least 1440 premature ventricular mcomplexes per 24 hours in a previous Holter recording were randomized to receive either 1.5 g/day n-3 fatty acids or placebo. Two 24-hour Holter recordings were made at baseline and two after the intervention period of ~14 weeks. Treatment did not significantly affect the incidence of premature ventricular complexes. It decreased on average by 867 per 24 hours in the fish oil group compared with the placebo group (95% confidence interval, -3187 to 1453). However, heart rate decreased significantly by on average 2.1 beats/min in the fish oil group compared with the placebo group (95% CI, -3.9 to -0.3). In conclusion, supplementation with 1.5 g/day of n-3 fatty acids from fish does not substantially suppress the number of premature ventricular complexes in a patient population with frequent premature ventricular complexes. This makes it less likely that n-3 fatty acids from fish reduce the risk of sudden cardiac death through preventing triggers of arrhythmia. However, n-3 fatty acids significantly decreased heart rate by 2.1 beats/min, which predicts a 6% lower risk of sudden death.