A new, large, retrospective observational cohort study (1) conducted in five Italian health units assessed the progress of 11,269 patients 12 months after being discharged from hospital following a myocardial infarction. Some 2,425 of the patients (21.5%) had received treatment including a daily dose of marine omega-3 fatty acids ethyl esters (ca. 850 mg 2:1 DHA:EPA) originally used in the famous GISSI study (2, 3) in 1999. Despite an adherence rate of slightly less than 80%, the patients treated with marine omega-3 fatty acids had a greatly reduced risk of sudden cardiac death (HR 0.76; 95% CI 0.59 to 0.97) and recurrent acute myocardial infarction (HR 0.65; 95% CI 0.49 to 0.87). This dramatic result is similar to that seen in the original GISSI studies (2, 3) and demonstrates that the effect still exists despite the widespread use of dual antiplatelet therapy and primary and early percutaneous coronary interventions (PCIs) in the years after the original GISSI trial was conducted.
A clue as to the mechanism behind this improvement may be gleaned from a recent intervention study that used 4 g of marine omega-3 fatty acids in patients one month after their initial heart attack (4). Here, measurement of cardiac magnetic resonance demonstrated that the intervention achieved significant reductions in the left ventricular end-systolic volume index and myocardial extracellular volume fraction.
Several studies have shown the additional benefit of marine omega-3 supplementation to patients who have experienced an acute myocardial infarctions and are already being treated with statins (5,6). The new Italian study (1) is able to corroborate these findings.
While several recent meta-analyses have cast doubt on the value of marine omega-3 fatty acids in the treatment of patients who have suffered a heart attack, this new large study from Italy (1) carried out in a “real-world” situation provides strong evidence that the current advice regarding treatment with marine omega-3 fatty acids needs to be reappraised.