Background: Coronary artery calcification (CAC) correlates with the extent of coronary atherosclerosis and, consequently, with an increased risk for cardiovascular events. CAC is more frequent in uremic patients than in the general population. Nearly all data about CAC relate to patients on dialysis therapy. This study evaluates the prevalence and extent of CAC in patients with chronic renal failure (CRF) not yet on dialysis therapy.
Methods: Consecutive outpatients with CRF not on dialysis therapy were enrolled and compared with controls (ie, healthy volunteers and patients with essential hypertension with normal renal function). Patients and controls were asymptomatic and had no previous history of myocardial infarction, coronary bypass surgery, or angioplasty. Patients with diabetes were excluded. Clinical characteristics, biochemical test results (included homocysteinemia and C-reactive protein level), and serum concentrations of calcium, phosphorus, and intact parathyroid hormone (iPTH) were evaluated in patients and controls. CACs were searched for and scored by means of spiral computed tomography (CT). To assess the CAC progression rate, spiral CT was repeated in some patients.
Results: Eighty-five patients and 55 controls were studied. Patients were aged 52 +/- 13 years and had a CRF duration of 6.3 +/- 5.6 years, glomerular filtration rate of 33.0 +/- 16.0 mL/min (0.55 +/- 0.27 mL/s), serum calcium level of 9.5 +/- 0.5 mg/dL (2.37 +/- 0.12 mmol/L), serum phosphorus level of 4.1 +/- 0.9 mg/dL (1.32 +/- 0.29 mmol/L), and serum iPTH level of 143 +/- 121 pg/mL (ng/L). CAC was found in 40% of patients and 13% of controls; calcification scores were 422 +/- 634 in patients and 43.9 +/- 33 in controls. Only age ( P < 0.001) was a predictor of CAC. In patients with a repeated score performed (after a mean of 7.9 months), calcification scores increased (from 383 +/- 627 to 682 +/- 890) in 8 of 10 patients.
Conclusion: CAC is already present in the early phase of CRF; the prevalence is greater in patients with CRF than in controls, but less than that reported in dialysis patients. Serum concentrations of calcium, phosphorus, iPTH, and inflammation markers do not predict the appearance or progression of CAC.