Effect of EPA + DHA supplementation on ECG measures (Table 
SECONDARY
Effect of EPA/DHA treatment on ECG measures.Treatment effect model adjusted for age, gender, race, BMI, mean blood pressure, and active treatment.QTc interval 1 represents QTc calculated with the Framingham formula, QTc interval 2 with the Fredericia formula.Table In secondary stratified analyses, results were similar for all ECG variables among those who reported fish intake above or below the median (1.5 per week). In analyses stratified by baseline EPA + DHA levels, there was nominal evidence for effect modification of the treatment effect on the PR interval. Among those with baseline levels below the median (< 2.7%), the difference in the net change in the PR interval was 4.87 ms (95% CI: 1.97–7.77) in the active versus the placebo group. In comparison, the difference in the net change was only 0.89 ms (95% CI: − 1.52–3.31) in those with EPA + DHA levels > 2.7% (