Sex hormone levels in patients with sudden cardiac arrest.

Background: Sex hormones are known to have significant effects on the pathophysiology of cardiovascular disease.

Objective: The purpose of this study was to study the association between sex hormone levels and sudden cardiac arrest (SCA).

Methods: In the ongoing Oregon Sudden Unexpected Death Study (catchment population approximately 1 million), cases of SCA were compared with matched controls. Testosterone and estradiol levels were measured from blood samples drawn at the time of the SCA event in cases and during a routine visit in controls.

Results: Among cases (n = 149, age 64.1 ± 11.7 years, 73.2% male), compared to controls (n = 149, 64.2 ± 11.6 years, 72.5% male), median testosterone levels were significantly lower in males (4.4 vs 5.4 ng/mL, P = .01). Median estradiol levels were higher in male (68 vs 52 pg/mL, P <.001) and female cases (54 vs 36 pg/mL, P <.001). In multivariate analysis, higher testosterone levels were associated with lower SCA odds only in males (odds ratio [OR] 0.75, 95% confidence interval [CI] 0.58-0.96, P = .02). Higher estradiol levels were associated with higher SCA odds in both males (OR 2.0, 95% CI 1.5-2.6, P <.001) and females (OR 3.5, 95% CI 1.9-6.4, P <.001). A higher testosterone/estrogen ratio was associated with lower SCA odds in males only (OR 0.5, 95% CI 0.4-0.7, P <.001). In a canine model of SCA, plasma testosterone levels were not significantly altered by the cardiac arrest event.

Conclusion: We observed significant differences in sex hormone levels in patients who suffered SCA, with potential mechanistic implications. The role of sex hormones in the genesis of fatal ventricular arrhythmias warrants further exploration.