Low Serum Calcium Increases Risk of SCA

Sudden cardiac arrest (SCA) is fatal for over 90% of patients, and more than half of men and close to 70% of women who die of SCA have no clinical history of heart disease prior to this cardiac event. It is one of the leading causes of death in the USA and kills more people than any single cancer.

Many patients who suffer SCA would not be considered high risk under current guidelines. These sobering facts drive the search for simple and relatively inexpensive ways to identify individuals at higher risk for SCA. Individuals with lower levels of calcium in the blood, which is easily monitored, are more likely to experience SCA than those with higher calcium levels.

A team of scientists working with those at the Cedars-Sinai Heart Institute (Los Angeles, CA, USA) measured serum calcium levels during routine medical care of 267 SCA cases and 445 control subjects. All SCA cases had had serum calcium levels measured in the 90 days prior to their cardiac arrest. Each patient's total serum calcium was corrected by their serum albumin level to estimate a more physiologically relevant corrected calcium level. Patients were included if their age was 18 years or older with available creatinine clearance (CrCl) and serum electrolyte levels for analyses to enable adjustment for renal function.

The scientists found that SCA cases had a significantly higher percentage of African Americans and patients with diabetes mellitus, chronic obstructive pulmonary disease, and chronic kidney disease compared to the control group. Cases were also more likely than controls to be on hemodialysis. In addition, diuretics, especially loop diuretics, were prescribed more for cases than for controls with no differences in the rate of utilization of beta blockers. Blood calcium levels lower than 8.95 mg/dL were associated with a 2.3-fold increase in odds of SCA as compared with levels higher than 9.55 mg/dL (odds ratio, 2.33).

Hirad Yarmohammadi, MD, MPH, a postdoctoral fellow at Cedars-Sinai and lead author of the study, said, “Our study showed that lower serum calcium levels, even within the normal range of values, may increase risk for sudden cardiac death. Although our findings may not be ready for routine clinical use in patients at this time, they are a step towards the goal of improving patient care by better prediction of risk.” The study was published on September 21, 2017, in the journal Mayo Clinic Proceedings.

Related Links:
Cedars-Sinai Heart Institute