|
Laura
A. Murphy, Eric
J. Rashba, Stephen R. Shorofsky, Karen MacMurdy, Michael R. Gold, University
of Maryland, Baltimore, Maryland.
|
|
Background: Gender has important influences
on cardiovascular disease including arrhythmias. Women have a lower incidence
of sudden cardiac death (SCD), but the mechanisms underlying this observation
are poorly understood. T-wave alternans (TWA) is an important marker of
ventricular arrhythmia vulnerability. However, the effects of gender on this
measure have not been evaluated.
Methods: This was a prospective study of 251 patients with ischemic
heart disease and left ventricular dysfunction (ejection fractions <
40%). The patients underwent electrophysiology study (EPS) and measurement of
TWA as part of the evaluation of suspected ventricular arrhythmias in the
absence of antiarrhythmic drugs or beta blockers.
Results: The cohort was 19% female with a mean age of 65 + 10
years and a mean ejection fraction of 27 + 8%. Women had higher
ejection fractions (29 + 9 vs. 27 + 8, p=0.03), lower rates of
inducible arrhythmias (56% vs 69%, p= 0.09), were less likely to be receiving
beta blockers chronically (48% vs 67%, p= 0.02) and were less likely to have
positive TWA tests (42% vs 63%, p=0.02). Multivariate analysis of 10 clinical
factors using TWA as the dependent variable revealed that female gender (OR
0.4, 95% CI 0.2-0.8, p=0.007), age (OR 1.04 per year interval, 95% CI
1.01-1.07, p=0.007), and digoxin therapy (OR 2.5, 95% CI 1.3-4.7, p=0.006)
were independent predictors of TWA.
Conclusions: Women are less likely to have abnormal TWA. Since TWA may
be mechanistically related to the pathogenesis of SCD, this finding could
contribute to the lower incidence of SCD among women.
|