Incidence and clinical relevance of coronary calcification detected by electron beam computed tomography in heart transplant recipients.

BACKGROUND Patients treated by cardiac transplantation who survive beyond one year are at significant risk from fatal coronary artery disease. The development of coronary artery calcification in these patients is discussed and methods available to detect it are reviewed. OBJECTIVES To assess the clinical importance of coronary artery calcium in heart transplant recipients. METHODS In a cohort of 102 cardiac transplant recipients, electron beam computed tomography was used to measure calcium in the coronary arterial wall 63 days to 9.1 years (median 4.6 years) after transplantation. The results were compared with angiographic findings and with conventional coronary disease risk factors. The patients were followed for a mean of 2.12 years (1.2-4.02 years) to assess the relationship between these findings and future cardiac events. RESULTS Forty-one (40.2%) had a stenosis of > 24% in one or more major coronary artery at angiography. Forty-six (45%) had a coronary calcium score > 0. The absence of calcium had a negative predictive value with respect to angiographic disease in any vessels of 87.5%. Logistic regression revealed that dyslipidaemia, systemic hypertension and organ ischaemic time were significant predictors of calcification. At follow-up, both an abnormal coronary angiogram and coronary calcium were found to be the only significant predictors of late events. Multivariate analysis suggested that the detection of coronary calcium did not offer any additional predictive information over that provided by the angiogram itself. CONCLUSION Electron beam computed tomography is well suited to the assessment of calcium in the coronary arteries of heart transplant recipients, although the mechanisms of this calcification remain poorly understood. Calcium is detected more frequently than would be suggested by studies using intravascular ultrasound. It is associated with the presence of angiographic disease, and with some conventional risk factors for coronary disease. At follow-up the presence of coronary calcium was associated with an adverse clinical outcome, as it is in conventional ischaemic heart disease.