Predictors of omega-3 index in patients with acute myocardial infarction

OBJECTIVE: To identify the patient and dietary characteristics associated with low omega-3 levels in patients with acute myocardial infarction (AMI) and determine whether these characteristics are useful to identify patients who may benefit from omega-3 testing and treatment.PATIENTS AND METHODS: Dietary habits of 1487 patients in the 24-center Translational Research Investigating Underlying disparities in acute Myocardial infarction Patients'' Health status (TRIUMPH) registry between April 11, 2005, and September 28, 2007, were assessed by asking about the frequency of fast food and nonfried fish consumption. All patients had erythrocyte omega-3 index measured at the time of hospital admission for AMI. We used multivariable linear regression to identify independent correlates of the omega-3 index and modified Poisson regression to predict risk of a low omega-3 index (<4%).RESULTS: The proportion of patients with a low omega-3 index increased with more frequent fast food intake (18.9% for <1 time monthly, 28.6% for 1-3 times monthly, 28.8% for 1-2 times weekly, and 37.6% for ≥3 times weekly; P<.001). In contrast, a low omega-3 index was less common among patients with more frequent fish intake (35.1% for <1 time monthly, 24.9% for 1-3 times monthly, 16.1% for 1-2 times weekly, and 21.1% for ≥3 times weekly; P<.001). Fish intake, older age, race other than white, and omega-3 supplementation were independently associated with a higher omega-3 index, whereas frequent fast food intake, smoking, and diabetes mellitus were associated with a lower omega-3 index.CONCLUSION: Potentially modifiable factors, such as patient-reported fast food intake, fish intake, and smoking, are independently associated with the omega-3 index in patients with AMI. These characteristics may be useful to identify patients who would benefit most from omega-3 supplementation and lifestyle modification.AMI = acute myocardial infarction; DHA = docosahexaenoic acid; EPA = eicosapentaenoic acid; RBC = red blood cell; TRIUMPH = Translational Research Investigating Underlying disparities in acute Myocardial infarction Patients'' Health statusA low red blood cell (RBC) omega-3 index (the sum of eicosapentaenoic acid [EPA] and docosahexaenoic acid [DHA]) is associated with greater long-term mortality in patients with coronary artery disease.^1,2 Because omega-3 supplementation reduces mortality in patients with cardiovascular disease,^3-5 it is possible that augmenting omega-3 levels in those with the lowest omega-3 indices would yield the greatest treatment benefit. Accordingly, routine assessment of patients'' omega-3 index could identify the highest-risk patients who are ideal targets for dietary modification and aggressive omega-3 supplementation. Despite these potential benefits and the availability of well-tolerated, affordable omega-3 supplements, routine testing of omega-3 fatty acid levels has been limited in acute myocardial infarction (AMI) populations because of its cost and limited availability at the point of care. Therefore, simple and inexpensive screening mechanisms are needed to identify patients who are likely to have a low omega-3 index and who may experience greater benefit from omega-3 index testing and treatment than those with a higher omega-3 index.Studies in asymptomatic patients, many of whom had no coronary artery disease, identified several patient characteristics associated with omega-3 levels. Specifically, omega-3 supplements, age, body mass index, diabetes, and smoking were independently associated with the omega-3 index.^6,7 To our knowledge, the patient characteristics and dietary behaviors associated with the omega-3 index have not been described in patients with incident AMI, a particularly high-risk population. Moreover, although poor dietary habits, such as frequent consumption of fast food, may influence omega-3 levels, no studies have examined the association between fast food intake and the omega-3 index. Therefore, we studied patients enrolled in a contemporary registry of AMI treatment and outcomes, the Translational Research Investigating Underlying disparities in acute Myocardial infarction Patients'' Health status (TRIUMPH) study, to describe the association between patient characteristics and omega-3 levels at the time of AMI. Our goal was to identify the independent predictors of omega-3 levels so that patients likely to have low levels of omega-3 could be recognized and considered for further testing and treatment.