Fatty acid turnover in the ischaemic compared to the non-ischaemic human heart

Cardiac extraction, oxidation and release of plasma free fatty acids (FFA) was measured by coronary sinus catheterization, utilizing infusions of 3H palmitate and 14C oleate, in patients with ischaemic heart disease (IHD) at rest and during pacing induced angina pectoris and, for comparison, in healthy men of similar and younger age and men with hypertriglyceridaemia (HTG). At rest IHD patients differed from healthy men only by greater cardiac fatty acid release, which correlated with a significant glycerol release. In IHD patients, unlike in healthy men, myocardial extraction of both palmitate and oleate decreased while fractional oxidation of oleate increased during pacing. Fatty acid release was unaltered. Men with HTG had at rest higher myocardial FFA extraction than IHD patients, which did not decrease during pacing, but like in the patients oleate fractional oxidation increased on pacing. It is concluded that, in the moderately ischaemic human heart, the restricted blood flow may contribute to limit the fatty acid flux into the myocardium. The augmented cardiac fatty acid release in IHD patients is not related to ischaemia per se but may derive from an increased amount of cardiac interstitial fat.