A higher proportion of men than of women fainted in the phase without nitroglycerin in tilt-induced vasovagal syncope

Abstract

Purpose Vasovagal syncope (VVS) affects more women than men. We determined whether this sex ratio affects tilt table test (TTT) results. Methods We retrospectively studied TTT outcomes in suspected VVS. TTT consisted of supine rest, a maximum 20 min of head-up tilt without and, if nitroglycerin was needed, a further maximum 20 min after nitroglycerin administration. TTT was terminated if VVS occurred. We used binary logistic regression for the entire TTT and for each phase, with VVS as outcome and age and sex as predictors. Results TTT provoked vasovagal (pre)syncope in 494 out of 766 tests (64%). The proportion of men and women who fainted during the entire TTT did not differ significantly between the sexes (p = 0.13, corrected for age). A lower proportion of women than men had VVS in the phase without nitroglycerin (odds ratio 0.54; 95% confidence interval 0.37-0.79; p = 0.002, corrected for age), whereas a higher proportion of women than men fainted after nitroglycerin (odds ratio 1.58; 95% confidence interval 1.13-2.21; p = 0.008, corrected for age). These sex differences remained significant after correction for a history of orthostatic versus emotional triggers. The effect of sex on TTT outcome was closely associated with differences of blood pressure change upon tilt-up (lower in men in both TTT phases: without nitroglycerin p = 0.003; with nitroglycerin p = 0.05), but not with heart rate changes. Conclusion Men were more susceptible to induction of VVS without nitroglycerin and women after it. The unexpected findings may be due to sex-specific pathophysiological differences.

Three decades of Clinical Autonomic Research and beyond

“…All COVID-19-related manuscripts are Open Access immediately upon publication. We also published a special issue on sex differences in cardiovascular autonomic control [ 1 , 3 , 4 , 8 , 9 , 11 ]. The reception of these series was exceptionally good.…”

Autonomic, endocrine, and psychological stress responses to different forms of blood draw: Results from a preregistered study

“…If these changes in HRV do reflect a vasovagal response, it would be a modest reaction, as no participant fainted or reported feelings consistent with pre-fainting (e.g., feeling lightheaded). And, it should be noted that women may be more susceptible to vasovagal reactions to venipuncture [57][58][59][60] (but see also [61]). As such, the findings presented here may reflect relatively larger changes in HRV to venipuncture than might be seen in a mixed sex/gender sample.…”

Autonomic, endocrine, and psychological stress responses to different forms of blood draw

“…If these changes in HRV do reflect a vasovagal response, it would be a modest reaction, as no participant fainted or reported feelings consistent with pre-fainting (e.g., feeling lightheaded). And, it should be noted that women may be more susceptible to vasovagal reactions to venipuncture [55][56][57][58] (but see also [59]). As such, the findings presented here may reflect relatively larger changes in HRV to venipuncture than might be seen in a mixed sex/gender sample.…”