Electron beam computed tomography in the evaluation of cardiac calcifications in chronic dialysis patients

Abstract

The purpose of this study was to assess the value of electron beam computed tomography in the detection of cardiac calcifications in coronaries and valves of dialysis patients and to determine the rate at which calcification progresses. Forty-nine chronic hemodialysis patients aged 28 to 74 years were compared with 102 nondialysis patients aged 32 to 73 years with documented or suspected coronary artery disease, all of whom underwent coronary angiography. We used high-resolution electron beam computed tomography scanning to make 30 axial slices with a distance of 3 mm between each slice. The number of calcifications, the surface area, and the average and highest density values were measured. We calculated a quantitative coronary artery calcium score and assessed calcification of mitral and aortic valves. In dialysis patients, the measurements were repeated after 12 months. The coronary artery calcium score was from 2.5-fold to fivefold higher in the dialysis patients than in the nondialysis patients. Hypertensive dialysis patients had higher calcium scores than nonhypertensive dialysis patients (P <0.05). A stepwise, multiple regression analysis confirmed the importance of age and hypertension. No correlation between calcium, phosphate, or parathyroid hormone values and the coronary calcium score was identified; however, the calcium score was inversely correlated with bone mass in the dialysis patients (r = 0.47, P <0.05). The mitral valve was calcified in 59% of dialysis patients, while the aortic valve was calcified in 55%. The coronary artery calcium score was correlated with aortic valvular, but not mitral valvular calcification. A repeat examination of the dialysis patients at an interval of 1 year showed a disturbing tendency for progression. Our data underscore the frequency and severity of coronary and valvular calcifications in dialysis patients, and illustrate the rapid progression of this calcification. Finally, they draw attention to hypertension as an important risk factor in this process.