People with the lowest blood calcium levels are twice as likely to suffer a cardiac arrest as those with the highest levels, a study found. The condition is fatal in more than 90 per cent of cases.
Scientists in the US compared blood calcium levels measured in 267 patients who experienced a cardiac arrest up to 90 days later and 445 others who did not go on to suffer a cardiac arrest.
Lead investigator Dr Sumeet Chugh, from the Cedars-Sinai Heart Institute in Los Angeles, said: “Our study found that serum calcium levels were lower in individuals who had a sudden cardiac arrest than in a control group.
“Patients with serum calcium in the lowest quartile (bottom 25 per cen) had twice the odds of sudden cardiac arrest compared to those in the highest quartile (top 25 per cent), even after controlling for multiple patient characteristics including demographics, cardiovascular risk factors and comorbidities, and medication use.
“Overall, it seems that further study is required to elucidate the mechanisms underlying the adverse associations with lower calcium levels and to determine whether controlling calcium levels improves the prognosis in the general population or in high-risk patients.”
Patients in the higher risk group had blood calcium levels of less than 8.95 milligrams per decilitre, which is just within the normal range of 8.5-10.2mg.
Cardiac arrest patients were significantly more likely to be African Americans and to suffer from diabetes, chronic obstructive pulmonary disease and chronic kidney disease.
The research appears in the journal Mayo Clinic Proceedings.
Dr Hirad Yarmohammadi, another member of the Cedars-Sinai team, 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.”
In an accompanying editorial, Dr Hon-Chi Lee, from the Mayo Clinic in Rochester, US, wrote: “This is the first report to show that low serum calcium levels measured close in time to the index event are independently associated with an increased risk of SCA (sudden cardiac death) in the general population.”