Gender difference in autonomic and hemodynamic reactions to abrupt coronary occlusion.

OBJECTIVES

We sought to determine whether there are gender-related differences in autonomic and hemodynamic responses to abrupt coronary occlusion.

BACKGROUND

The risk of sudden death before hospital admission is higher in men with an acute myocardial infarction. The reasons for this gender-related difference are not well understood. Cardiovascular autonomic regulation modifies the outcome of acute coronary events, and there are gender differences in the autonomic regulation of heart rate (HR) in normal physiologic circumstances.

METHODS

We analyzed the changes in HR, HR variability and blood pressure and the occurrence of ventricular ectopic beats during a 2-min coronary occlusion in 140 men and 65 women referred for single-vessel coronary angioplasty. The ranges of nonspecific responses were determined by analyzing a control group of 19 patients with no ischemia during a 2-min balloon inflation in a totally occluded coronary artery.

RESULTS

Women more often had ST segment changes (p < 0.01) and chest pain (p < 0.05) during the occlusion. Significant bradycardia or increase in HR variability as a sign of vagal activation occurred more often in women than in men (31% vs. 13%, p < 0.01 and 25% vs. 11%, p < 0.05, respectively). Coronary occlusion also more often caused (28% vs. 11%, p < 0.01) a decrease in blood pressure in women. The most pronounced female preponderance was in the incidence of Bezold-Jarisch-type reaction (i.e., simultaneous bradycardia and decrease in blood pressure [16% vs. 0.7%, p < 0.0001]). Logistic regression models developed to analyze the significance of gender while controlling for baseline variables and signs of ischemia identified female gender to be an independent predictor of bradycardic reactions (odds ratio [OR] 3.2, 95% confidence interval [CI] 1.4 to 7.7, p < 0.01), hypotensive reactions (OR 2.6, 95% CI 1.1 to 6.0, p < 0.05) and Bezold-Jarisch-type response (OR 22.2, 95% CI 2.5 to 200, p < 0.01). Significance of female gender as a protector against early coronary occlusion-induced ventricular ectopic beats emerged as having borderline significance (OR 0.4, CI 0.1 to 1.1, p = 0.07).

CONCLUSIONS

Vagal activation is more common in women than in men during abrupt coronary occlusion and may have beneficial antiarrhythmic effects, modifying the outcome of acute coronary events.