The role of omega-3 fatty acids and aspirin in primary prevention

Almost every heart attack is due to coronary heart disease. That makes prevention all the more important, especially in at-risk patients. Alongside giving up nicotine, a healthy lifestyle with enough exercise, a balanced diet and little stress certainly plays a major part in primary prevention. In addition, all guidelines recommend a fish-rich diet and 1 g of fish oil capsules, as Prof. Dr. med. Franz Eberli of Zurich explained. This was based on study results from the 1980s [1–6], in which omega-3 fatty acid supplementation was associated with a reduction in cardiovascular mortality.

However, this hypothesis could not be confirmed in follow-up studies. Only in open-label studies was a trend towards an effect apparent. In 2018 a Cochrane review [7] analysed the results of 79 randomised clinical trials. It found little or no effect of omega-3 fatty acids on all-cause mortality, cardiovascular mortality, cardiovascular events, stroke and arrhythmias. A recently published study [8] of 25,871 patients without cardiovascular disease confirmed the new findings. There was no difference in cardiovascular events between 1 g of fish oil and placebo.

Aspirin brings no benefit

Several studies in different patient groups that examined the benefit of aspirin in primary prevention reached similar results. A multicentre study [9] randomised 12,546 patients 1:1 to take 100 mg/day of ASA or placebo. The primary endpoint was a combination of cardiovascular death, heart attack, unstable angina or stroke/transient ischaemic attack. One of these events occurred in 269 patients (4.29%) in the verum group and 281 patients (4.48%) in the placebo group. So there was no clear advantage.

A second study [10] examined the protection ASA offers against cardiovascular events in 15,480 people with diabetes (average age 63). Here too, one group was given 100 mg/day of ASA or placebo. The primary efficacy endpoint was a serious vascular event. Over a follow-up period of 7.4 years, the risk of a vascular event was indeed moderately reduced, by 12%. However, a high number of severe haemorrhagic complications (up 29%) cancelled out this benefit. 'Good treatment of hypertension and lowering cholesterol therefore remain the most important primary preventive measures in high-risk patients,' Prof. Eberli concluded.

Source: 85th Medical Congress Davos, 7–9 February 2019

References:

1. NEJM 1985; 312: 1205–1209.
2. NEJM 1985; 313: 820–824.
3. Circulation 202; 106: 2747.
4. Lancet 189; 334:757–761.
5. Lancet 1999; 354: 474–455.
6. Circulation 2017; 135: 867–884.
7. Cochrane Database Syst Rev 2018; 7: CD03177.
8. NEJM 2019; 380: 23–32.
9. Lancet 10152; 392: 1036–1046.
10. Am Heart J 2018; 198: 135–144.

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Leoni Burggraf