Explained and unexplained ischemic heart disease risk after renal transplantation

Abstract

Whether the high incidence of ischemic heart disease (IHD) among renal transplant patients can be attributed to the same risk factors that have been identified in the general population is unclear. The risk for major IHD events occurring >1 yr after transplantation among 1124 transplant recipients was estimated by using the risk calculated from the Framingham Heart Study (FHS). The FHS risk predicted IHD (relative risk, 1.28; 95% confidence interval, 1.20 to 1.40; P: < 0.001); however, the FHS risk tended to underestimate the risk of IHD for renal transplant recipients. This was largely attributable to increased risks associated with diabetes mellitus and, to a lesser extent, age and cigarette smoking for renal transplant recipients. For men, the relative risks for diabetes mellitus were 2.78 (1.73 to 4.49) and 1.53 for the transplant recipient and FHS populations, respectively; the relative risks for age (in years) were 1.06 (1.04 to 1.08) and 1.05, respectively, and those for smoking were 1.95 (1.20 to 3.19) and 1.69, respectively. For women, the relative risks for diabetes mellitus were 5.40 (2.73 to 10.66) and 1.82, respectively. There was a tendency for the risk associated with cholesterol levels to be higher for transplant recipients, compared with the FHS population, but the risks associated with high-density lipoprotein cholesterol levels and BP appeared to be comparable. Independent of these and other risk factors, the adjusted risk of IHD for the transplant recipient population has decreased. Compared with the era before 1986, transplantation between 1986 and 1992 was associated with a lower relative risk of 0.60 (0.39 to 0.92); transplantation after 1992 was associated with an even lower relative risk of 0.27 (0.11 to 0.63) for IHD. Of concern was the fact that dihydropyridine calcium channel antagonists were associated with an increased risk for IHD (relative risk, 2.26; 95% confidence interval, 1.24 to 4.12; P: = 0. 008), and this association was independent of other antihypertensive agents and risk factors. Therefore, although the FHS risk predicts IHD after renal transplantation, it tends to underestimate the risks, especially the risk associated with diabetes mellitus. The unexpected finding that dihydropyridine calcium channel antagonists were associated with an increased IHD risk merits further evaluation.