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Low calcium levels linked to risk for sudden cardiac arrest
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Lower serum calcium levels were associated with a significant increased risk for sudden cardiac arrest, new data show.
“It is estimated that approximately 300,000 individuals die of sudden cardiac arrest annually in the United States,” Sumeet S. Chugh, MD, medical director of the Heart Rhythm Center at the Cedars-Sinai Heart Institute, and colleagues wrote. “However, more than half of men and close to 70% of women who die of [sudden cardiac arrest] have no clinical history of heart disease before their cardiac arrest. Hence, it is important to identify other risk factors and mediators for [sudden cardiac arrest] to improve risk stratification and preventive strategies in the general population.”
Chugh and colleagues used data from the Oregon Sudden Unexpected Death Study from 2002 to 2015 to study whether serum calcium levels were associated with cardiac arrest.
The data included 267 sudden cardiac arrest cases (66% men) and 445 controls (71% men), with all patients who had cardiac arrest having serum calcium levels measured within 90 days of their event.
Total serum calcium of all participants was corrected by their serum albumin level to estimate a more physiologically relevant calcium level.
Calcium and cardiac arrest
Those with sudden cardiac arrest were significantly more likely to be black (12% vs. 3%), have diabetes (46% vs. 28%) and have chronic kidney disease (38% vs. 16%). They were also more likely to be on hemodialysis (12% vs. 1%) and be prescribed diuretics (54% vs. 38%), especially loop diuretics (46% vs. 16%), compared with controls.
Participants with blood calcium levels less than 8.95 mg/dL were 2.3 times more likely to have sudden cardiac arrest compared with those with levels higher than 9.55 mg/dL (OR = 2.33; 95% CI, 1.17-4.61). For each 1-unit decrease in serum calcium, there was an increase in risk for sudden cardiac arrest (OR = 1.63; 95% CI, 1.6-2.51).
After evaluation of ECG, the researchers found that patients with sudden cardiac arrest had significantly prolonged corrected QT intervals (465 ms) compared with controls (425 ms).
“Lower serum [calcium] levels were independently associated with an increased risk of [sudden cardiac arrest] in the general population,” the researchers wrote. “These findings have potential implications for mechanisms as well as prevention of [sudden cardiac arrest] and warrant further evaluation.”
More study needed
In an accompanying editorial, Hon-Chi Lee, MD, PhD, of the department of cardiovascular medicine at the Mayo Clinic in Rochester, Minnesota, highlighted three main implications from the study:
Serum calcium levels should be examined and followed over time.
Lower calcium levels may be considered a risk factor for sudden cardiac death and should be considered in the presence of other risk factors.
More research is needed to determine whether individuals would benefit from more calcium intake or supplementation.
“Other studies did not show any significant association between calcium intake and cardiovascular events and mortality,” Lee wrote. “The correct approach in the management of such patients will await prudently designed clinical studies involving careful monitoring of serum calcium levels in vulnerable patients.” by Cassie Homer
Disclosures: The authors and Lee report no relevant financial disclosures.
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