Plasma kinetics of a cholesterol-rich microemulsion in patients submitted to heart transplantation.

BACKGROUND: Development of coronary graft disease is currently the main cause of late heart-transplantation (HT) failure. HT patients frequently show hypercholesterolemia as well as alterations in chylomicron metabolism. These postHT changes may be important in coronary graft disease development. To clarify whether hypercholesterolemia is caused by decreased low-density lipoprotein (LDL) removal from the plasma, we studied the plasma kinetics of a cholesterol-rich emulsion that binds to LDL receptor.
METHODS: We studied 13 HT patients and 13 healthy normolipidemic subjects paired for sex, age, and body mass index. An emulsion labeled with C-cholesteryl oleate was injected intravenously, and blood samples were collected in predetermined intervals (5 minutes, 1, 2, 4, 6, and 8 hours) to determine the radioactivity decay curves and to calculate the fractional clearance rates (FCR).
RESULTS: The plasma level of total cholesterol, LDL cholesterol, high-density lipoprotein cholesterol, and apo B were greater in HT group than in the control group (P<0.005). FCR C-cholesteryl oleate was smaller in HT patients when compared with the control group (P=0.02).
CONCLUSION: The results showed that HT patients have a deficiency in the mechanisms of LDL removal from the plasma, as tested by the cholesterol-rich emulsion, and this may be important in the development of coronary graft disease.