MAXIMAL ASCENDING AND DESCENDING SLOPES OF THE T-WAVE IN MEN AND WOMEN

To investigate possible sex differences in the dynamics of T wave gene ration, the maximum instantaneous slope of the ascending and descend i ng limbs of the T wave (max dV/dt and min dV/dt, respectively), were c alculated. These rate of repolarization parameters,, as well as more t raditional repolarization duration parameters (QT, JT, Q to T wave pea k [QTm] and J to T wave peak [JTm]), were measured by computer using d igitized electrocardiograms (ECGs) from the V-5 lead in 562 normal sub jects (443 men and 119 women; mean age 37 years), whose heart rates (H Rs) were confined to one of three narrow ranges, namely 60 +/- 1, 70 /- 1, or 80 +/- 1 beats/min. In both men and women, for each HR range absolute values of min dV/dt exceeded those of max dV/dt (P < .0001). However, absolute values of both max dV/dt and min dV/dt were consiste ntly greater in men than in women for each HR range (P < .0001 at HR 6 0 +/- 1; P < .02 at HR 70 +/- 1, or 80 +/- 1). By using correlation an alysis, max dV/dt and min dV/dt were shown to be independent of the re polarization duration variables (\r\ < .30). Thus, whereas in both men and women the descending limb of the T wave is steeper than the ascen ding limb, the maximum slope oi each limb of the T wave is steeper in men than in women. These findings add to a growing body of data indica ting fundamental sex differences in the physiology of cardiac repolari zation and propensity to torsade de pointes.