Chylomicron metabolism in patients submitted to cardiac transplantation

Background. Development of coronary graft disease is the most important cau se of late heart graft failure. Alterations in plasma lipid profile are fre quent in heart transplant (HT) patients, hut they seem not to be prominent. Currently, the metabolism of chylomicrons, the lipoproteins that carry die tary lipids absorbed by the intestine, was evaluated because chylomicron re mnants are considered atherogenic, Methods. An emulsion labeled with H-3-triolein and C-14-cholesteryl oleate and known to mimic the metabolic behavior of chylomicrons was injected intr avenously after a 12-hr fast into 34 HT patients, 24 patients with end-stag e heart failure (ESHF), and 30 healthy normolipidemic subjects. The plasma disappearance curves Of the radioisotopes were determined from blood sample s collected over 1 hr, In some of the patients and in controls, in vitro po stheparin lipolytic activity was measured and an oral fat load test with po stprandial measurement of triglyceridemia was performed. Results. Fractional clearance rate (in m(-1), median [25%; 75%]) of both em ulsion H-3-triolein and C-14-cholesteryl oleate was extremely diminished in HT patients (HT: 0.0114 [0.0114; 0.0179] and 0.2x10(-8) [0.2x10(-8); 0.004 1, respectively]; ESHF: 0.0226 [0.0223; 0.0568] and 0.0160 [0.0055; 0.0189] ; control subjects: 0.0270 [0.0226; 0.0392] and 0.0090 [0.0042; 0.0180], re spectively, P<0.05), HT patients also had reduced postheparin lipolysis and marked elevation of postprandial triglyceridemia compared with the control s. Conclusions. HT patients develop accumulation in the plasma of chylomicrons and their remnants. The observed alterations were so intense that they may suggest an important involvement of atherogenic chylomicron remnants in co ronary graft disease.