Omega-3 fatty acids and the prevention of AF following coronary artery bypass surgery

It has been well documented that populations that have a high fish intake have a low incidence of coronary heart disease and death.1 Omega-3 oils have been demonstrated to reduce sudden death from ventricular fibrillation, presumably by stabilising the electrical activity at the cell membrane. Experimental in vitro and animal studies suggest that fish oil has direct cardiac electrophysiological effects.2 In animal experiments infused fish oils slow heart rate (HR) and alter the QT interval, both HR and abnormal QT interval predict arrhythmic events in humans.3 Mozaffarian et al4 have previously shown that fish oil lowers HR. More recently the associations between usual consumption of fish and marine omega-3 fish oil and electrocardiograph (ECG) measures among 5096 women and men aged 65 years and over enrolled in the Cardiovascular Health Study (CHS) have been investigated.5 The aim of the study was to investigate if fish consumption could reduce the incidence of sudden death and atrial fibrillation possible related to antiarrhythmic effects. A cross sectional cohort analysis among participants in the CHS (who were randomly selected) was performed, evaluating usual dietary fish intake and ECG measures of heart rate, atrioventricular conduction (PR interval), ventricular repolarisation (QT interval) and ventricular conduction (QRS interval). Multi-variant models were adjusted for age, gender, race, education, smoking, body mass index, diabetes, coronary heart disease, physical activity and intakes of beef or pork, fried fish, fruits, vegetables, alcohol and total calories. Consumption of fish (comparing the highest to the lower intake) was associated with lower heart rate (–3.2 bpm, 95% CI: –1.3–5.1, p<0.001), slower atrioventricular conduction (PR interval plus 7.2 ms, 95% CI: 1.4–12.9, p=0.03) and subsequently lower likelihood of prolonged QT (RR: 0.50, 95% CI: 0.27–0.25, p=0.03). Fish intake was not associated with ventricular conduction (p=0.60). The findings were similar to estimated intake of omega-3 fatty acids: a 1 g/day intake was associated with 2.3 bpm lower heart rate (95% CI: 0.9–3.7), 7.6 ms longer PR interval (95% CI: 3.3–11.9) and 46% lower likelihood of prolonged QT (RR: 0.54, 95% CI: 0.33–0.88). This large population based study suggested that dietary intake was associated with cardiac electrophysiology in humans, including heart rate, atrioventricular conduction, and ventricular repolarisation, with potential implications for arrhythmic risk.5