During the last decade, it has become evident that altered myocardial metabolism is a hallmark of heart failure (HF) [1–4]. In the foetal heart, glucose is the main energy source. However, free fatty acids (FFAs) are the main myocardial substrate (∼70%) postnatally (for review, see ref. ). Although FFAs provide the highest ATP yield, FFA metabolism requires more oxygen than glucose metabolism and is thus less energy efficient. Hence, high plasma FFA concentrations may be detrimental to the heart, increasing oxygen consumption for any given workload, and circulating FFA levels may be an important regulator of myocardial substrate metabolism in HF, potentially contributing to myocardial ischaemia and dysfunction.
Membrane phospholipids and their constituent fatty acids (FAs) are active components of biological membranes and play an important role in signal transduction and cellular metabolism. The composition of FAs may also be of importance for myocardial function [5, 6]. Hence, it has been reported that greater levels of saturated FAs may increase the risk of HF in apparently healthy individuals and, in the same population, arachidonic acid and n-3 polyunsaturated FAs (PUFAs) were found to decrease the risk of HF in women . Also, in a large community-based cohort of Japanese men and women, there was an inverse association between fish and n-3 PUFA dietary intakes and cardiovascular death, especially from HF . Moreover, n-3 PUFA supplementation was recently shown to decrease mortality and admission to hospital for cardiovascular reasons in patients with HF, further supporting a beneficial effect of these FAs on myocardial function . However, whereas several studies have investigated the role of n-3 PUFAs in HF, few have examined the composition of other FAs in patients with HF in relation to disease severity.
To further elucidate the role of FAs and their composition in HF, we investigated whether the total spectrum of FA composition in plasma is altered in clinical HF and whether any alterations in these parameters are correlated with the severity of disease.