Serum phosphate is an independent predictor of the total aortic calcification volume in non-hemodialysis patients undergoing cardiovascular surgery

Background: A high serum phosphate level is a well-known risk factor for vascular calcification (VC) in patients on hemodialysis (HD). However, the association between the serum phosphate level and VC in non-HD patients is unclear. Our aim was to assess the impact of serum phosphate level on aortic calcification (AC) volume in non-HD patients undergoing cardiovascular surgery. Methods: A total of 117 patients who underwent thoracoabdominal computed tomography as a preoperative general evaluation before cardiovascular surgery were enrolled. The total AC volume was quantified using the volume-rendering method by extracting the area >= 130 HU within the entire aorta. The total AC volume index (AC-VI) was estimated as the total AC volume divided by the body surface area. Results: In the 117 patients (64.7 +/- 13.1 years, 39% women), the median total AC-VI was 1.23 mL/m(2). The mean estimated glomerular filtration rate (eGFR), adjusted serum calcium levels, and serum phosphate levels were 63.8 +/- 19.9 mi./min/1.73 m(2), 9.1 +/- 0.4 mg/dL, and 3.6 +/- 0.6 mgidL, respectively. When the patients were classified into four quartiles based on their total AC-VI value, the serum phosphate level showed a positive correlation with a probability of being in the highest AC-VI quartile (R-2 = 0.0146, p = 0.0383) whereas the adjusted serum calcium level did not show a significant correlation (R-2 = 0.0040, p = 0.2615). A similar relationship between the serum phosphate level, adjusted serum calcium level, and AC-VI was confirmed when the total AC-VI was divided into the thoracic AC-VI and abdominal AC-VI. Multivariate analysis indicated that the serum phosphate level was an independent positive predictor of higher total AC-VI quartiles (beta = 0.8013, p = 0.0160). Conclusions: An increase in serum phosphate level was associated with an increased AC burden in non HD patients undergoing cardiovascular surgery. (C) 2015 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.