Key result
Scanning electron microscopy identified no calcium phosphate micro-crystals in the blood of patients with or without aortic stenosis, despite cases having significantly higher serum calcium phosphate levels (2.67 vs 2.47 mmol/L, p=0.005).
Why the study?
Does scanning electron microscopy detect calcium phosphate micro-crystals in the blood of patients with aortic stenosis compared to unaffected controls?
Case-Control (n=132)
Single-blind
No
Does scanning electron microscopy detect calcium phosphate micro-crystals in the blood of patients with aortic stenosis compared to unaffected controls?
Although serum calcium phosphate levels are higher in patients with aortic stenosis, calcium phosphate micro-crystals do not precipitate freely in the blood and cannot be detected by scanning electron microscopy.
No circulating micro-crystals detected despite higher serum levels; leaves open local valvular mechanisms in aortic stenosis.
BACKGROUND: Micro-crystals of calcium phosphate have been detected on the aortic valve of patients with aortic stenosis using scanning electron microscopy. It is not known whether crystalisation is specific to heart valve tissue or a general blood-derived process. METHODS: To this end we modified the method to determine whether calcium phosphate micro-crystals were present in the blood of patients with aortic stenosis. The method was first validated by adding synthetic calcium phosphate hydroxyapatite micro-crystals to healthy volunteer blood samples and determining the lower limit of detection. Then the method was used to examine the blood of 63 patients with echocardiographically confirmed aortic stenosis and 69 unaffected controls undergoing echocardiography for other reasons. Serum calcium and phosphate were measured and the calcium phosphate product compared in cases and controls. RESULTS: In the validation study, synthetic hydroxyapatite micro-crystals were identified down to a lower concentration limit of 0.008mg/mL. In the experimental study no particles were identified in any patient, with or without aortic stenosis, even though serum calcium phosphate was higher in cases compared with controls 2.6mmol/L (2.58-2.77) versus 2.47mmol/L (2.36-2.57), p = 0.005 for the difference. CONCLUSION: The results of our study confirm a positive association between serum calcium phosphate and aortic stenosis, but indicate that the calcium phosphate particles found in valve tissue do not precipitate freely in the blood.
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Wald et al. (2018) conducted a case-control in Aortic stenosis (n=132). Aortic stenosis vs. Unaffected controls was evaluated on Presence of calcium phosphate micro-crystals in blood. Scanning electron microscopy identified no calcium phosphate micro-crystals in the blood of patients with or without aortic stenosis, despite cases having significantly higher serum calcium phosphate levels (2.67 vs 2.47 mmol/L, p=0.005).
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