Calcium, Phosphate and the Risk of Cardiovascular Events and All-Cause Mortality in a Population With Stable Coronary Heart Disease

Study Questions:

Are high serum calcium and phosphate levels associated with increased risk of cardiovascular disease (CVD) among patients with pre-existing heart disease?

Methods:

A cohort of patients in the KOAROLA study initially enrolled (from January 1999 to May 2000) in a 3-week cardiac rehabilitation program was used for the present analysis. The cohort was followed over an 8-year period. All patients had experienced an acute CV event prior to enrollment, and were between the ages of 30 and 70 years. Follow-up for CV events was completed at 1, 3, 4, 5, 6, and 8 years post-enrollment. CV events included nonfatal myocardial infarction, or ischemic stroke, and CV events.

Results:

A total of 1,206 patients were included in the cohort. Calcium levels ranged from 8.7-13.11 mg/dl and from 2.17-12.70 mg/dl for phosphate. High calcium levels were strongly associated with risk of death (hazard ratio [HR], 2.39; 95% confidence interval [CI], 1.22-4.66) comparing the fourth quartile to the first quartile after adjustment for potential confounders, but was not associated with fatal and nonfatal cardiovascular event incidence. The calcium to albumin ratio was also associated with all-cause mortality (HR, 2.66; 95% CI, 1.35-5.22), and was mildly associated with CV event incidence (HR, 1.74; 95% CI, 1.00-3.05). Serum phosphate was not associated with all-cause mortality or CV events.

Conclusions:

The investigators concluded that serum calcium levels and the ratio of calcium to albumin were associated with all-cause mortality among patients with heart disease.

Perspective:

Although factors such as renal function were included in multivariate models, residual confounding from renal function may still be present. As the authors point out, additional research is required to fully understand the prognostic significance of these findings, and to determine if calcium supplementation would influence these findings.

Clinical Topics: Atherosclerotic Disease (CAD/PAD)

Keywords: Heart Diseases, Incidence, Prognosis, Coronary Artery Disease, Myocardial Infarction, Hypercalcemia, Follow-Up Studies, Cardiology, Cardiovascular Diseases, Risk Factors, Calcium, Phosphates


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