Lower Levels of Testosterone in Blood Linked to Risk of Sudden Cardiac Arrest

Research suggests that low testosterone levels may indicate that men face a greater risk of sudden cardiac arrest.

A study team from Cedars-Sinai Heart Institute, which published its findings in Heart Rhythm, analyzed sex hormone levels in 149 patients who experienced sudden attacks and found unusually low testosterone levels among the men and unusually high estradiol levels among both the men and the women.

“Because [sudden cardiac arrest] is usually fatal, we are constantly looking for ways to predict which patients are susceptible so we can concentrate on prevention,” said study author Sumeet Chugh, MD, in a news release that accompanied publication of the results. “If we wait until someone has a [sudden cardiac arrest], it is usually too late for treatment.”

Chugh and his colleagues compared hormone levels from the cardiac-arrest victims with those from a group of demographically similar control subjects.

The median testosterone level for men who suffered cardiac arrest was 4.4 ng/mL. The median testosterone level for men from the control group was 5.4 ng/mL (P = .01). Testosterone levels did not differ significantly between women in the study and control groups.

Median estradiol levels, however, varied between victims and controls for both men (68 pg/mL vs. 52 pg/mL; P<.001) and women (54 pg/mL vs. 36 pg/mL; P<.001). Multivariate analysis indicated that higher testosterone levels were associated with a significantly lower risk of sudden cardiac arrest for men (odds ratio [OR] = 0.75; 95% CI, 0.58-0.96).

The association between high estradiol levels and increased risk was even more dramatic in both men (OR=2; 95% CI, 1.5-2.6) and women (OR=3.5; 95% CI, 1.9-6.4). High ratios of testosterone to estrogen were associated with greatly reduced risk in men (OR=0.5; 95% CI, 0.4-0.7) but not in women.

“This is the first time it has been reported that there is an association between sex hormone levels and [sudden cardiac arrest],” Chugh said. “While these findings need to be confirmed by other studies, they suggest that higher testosterone levels in men may offer protection from sudden cardiac arrest and lower levels of estrogen may protect both men and women.”

The new research appears to provide more evidence that testosterone protects the heart rather than hurting it, but different studies have come down on different sides of that issue.

The US Food and Drug Administration has been investigating the matter since the publication of two large studies that linked testosterone therapy with adverse events.

The first paper, which was published in JAMA, found significant positive correlation between testosterone replacement and the likelihood of stroke, myocardial infarction (MI) and death. The second study, which was published in PLoS ONE, correlated testosterone therapy with a dramatically higher risk of heart disease among older patients and younger men with a history of heart disease.

Since then, however, journals have published a number of studies that have correlated testosterone therapy (or higher testosterone levels) with cardiac health. The largest of those, an analysis of records from 25,000 patients found no overall correlation between testosterone therapy and MI but a significant negative correlation between treatment and MI among the 25% of men who faced the highest risk of MI.

Such results led staffers at the FDA to conclude earlier this month that there’s no convincing evidence of any significant association between testosterone therapy and adverse cardiovascular events. A pair of FDA advisory committees will meet later this month to consider the matter further.