FAST PROGRESSION OF CORONARY ARTERY CALCIFICATION IN PRE-DIALYSIS PATIENTS. SEARCH FOR NEW PATHOGENETIC FACTORS?

Coronary artery calcification (CAC) are frequent in dialysis patients and regarded as factor responsible for high cardiovascular morbidity and mortality. In contrast to general population progression of CAC is faster in dialysis where calcium load from bath, high oral calcium supplementation, hyper-PTH, alteration of phosphate and calcium metabolism play a crucial role. The prevalence and rate of CAC progression have never been evaluated in pre-dialysis stages. In the present study prevalence and rate of CAC progression were assessed in patients with different degree of chronic renal failure not yet on dialysis. Out-patients with stable CKI were enrolled. At calcium, phosphorus, urea, creatinine, glucose, total protein, albumin, serum electrolytes, cholesterol, triglycerides, total alkaline phosphatase, homocysteine, CPR, PTH were assayed. Biochemistry and CT scan were repeated in 15 patients 8 months after the baseline evaluation in order to verify the rate of CAC progression. CT scan was performed with multi-slice spiral scanner (GE Medical Systems). Parameters used for data acquisition were: 140 kVp, 360 mAs, slice width 2.5 mm, gantry rotation time 0.5 s, thick/speed 2.5 mm/4i. Data were reconstructed with a standard algorithm, prospective Gating, 512 X 512 matrix, SFOV 50 cm2, DFOV 25 cm2. The left main coronary artery (LMA), left anterior descending artery (LAD), circumflex artery (Cx), right coronary artery (RCA) were scored; total calcium score was reported as the sum of plaques found in all coronaries. Eighty-three (73 male, 10 female; mean age 51.313, range 18-70 years) patients with CKI (mean Ccr 32.516.6, range 10-70 ml/min) were evaluated. Clinical and biochemical characteristics were: BMI: 274, duration of CKI: 5.34.1 years, PTH: 140110 pg/ml, serum calcium: 9.50.5 mg/dL, serum P: 4.00.7 mg/dL, Ca x P product: 36.77.3 mg2dL2, total cholesterol: 19040 mg/dL, triglycerides 16090 mg/dL, HDL cholesterol: 468 mg/dL, PAS 13211 mmHg, PAD: 814.5 mmHg. Prevalence of CAC was 39,7% and 5%, respectively in patients with CKI and control group (age and sex matched subjects without CKI). Mean total calcium score was 400500 mm3. Calcified patients had higher age (598 vs.46±12; p<0.01). No changes were found in biochemical parameters of 15 patients at follow-up; in fact, PTH was 110±95 and 113±100 pg/ml, Creatinine clearance 31±11 and 31±14 ml/min, P 4.3±0,9 and 4.1±0.7 mg/dL, Ca 9.3±0.6 and 9.6±0.5 mg/dL, total cholesterol 190±52 and 220±68 mg/dL, triglycerides 178±110 and 182±107 mg/dL, respectively in baseline and after 8 months. In contrast total calcium score dramatically increased from 285±468 mm3 to 555±708 mm3 (p<0.05). All pre-existing plaques rose in volume while in one patient plaque appeared ex novo. The data of the present study clearly indicate that prevalence of CAC is many fold higher in pre dialysis patients than that of general population (39% vs. 5%) indicating an evident causal relationship with CKI. Therefore, the assessment of CAC in these patients is mandatory in order to prevent or reduce fatal and not fatal cardiovascular events. But the most important and very new finding is the impressive and fast progression of plaque volume in absence of evident alteration of common biochemical parameters suggesting the need for searching new pathogenetic factors. Keywords: imaging techniques; progression of renal disease; phosphates; renal failure: chronic Session: Poster Session II: Calcification