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

BackgroundA 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.MethodsA 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.ResultsIn the 117 patients (64.7 ± 13.1 years, 39% women), the median total AC-VI was 1.23 mL/m2. The mean estimated glomerular filtration rate (eGFR), adjusted serum calcium levels, and serum phosphate levels were 63.8 ± 19.9 mL/min/1.73 m2, 9.1 ± 0.4 mg/dL, and 3.6 ± 0.6 mg/dL, 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 (R2 = 0.0146, p = 0.0383) whereas the adjusted serum calcium level did not show a significant correlation (R2 = 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 (β = 0.8013, p = 0.0160).ConclusionsAn increase in serum phosphate level was associated with an increased AC burden in non-HD patients undergoing cardiovascular surgery.