Parasympathetic response in women with coronary vascular dysfunction during mental stress compared to those with non-cardiac chest pain and reference controls

Background: Coronary vascular dysfunction (CVaD) contributes to ischemia even in the absence of obstructive coronary artery disease. We hypothesize that abnormal autonomic reactivity to mental stress is a key pathophysiologic mechanism in CVaD compared to non-cardiac chest pain (NCCP) and reference control (RC) groups. Methods: Seventy women (35 with CVaD diagnosed by coronary function testing, 19 with NCCP, and 16 RC) underwent mental stress testing (arithmetic and anger recall) in the Cardiac Autonomic Nervous System study. RC group was asymptomatic with no risk factors and normal exercise treadmill testing. Frequency domain heart rate variability (HRV, ms²) was obtained at baseline and during mental stress, with high frequency (HF) power as an accepted parasympathetic measure. Low frequency (LF)/HF ratio may reflect sympathetic dominance. ANOVA was used for comparisons. Results: CVaD group was older compared to NCCP (57.1 ± 9.6 vs. 50.4 ± 11.3 years, p = 0.025, respectively), but age-matched to RC group (54.6 ± 14.5, p = 0.45). HRV was similar at baseline among the groups. During anger recall, CVaD group had lower HF HRV vs. NCCP (5.03 ± 1.05 vs 6.00 ± 1.17, p = 0.006, respectively), but not vs. RC (5.74 ± 1.02, p = 0.077). During arithmetic, CVaD group had lower HF HRV vs. NCCP (5.06 ± 1.12 vs. 6.00 ± 1.17, p = 0.007, respectively) and RC (6.04 ± 0.83, p = 0.01) groups. LF/HF ratio did not differ among the three groups. Conclusions: Women with CVaD demonstrate a greater stress-induced vagal withdrawal compared to those with NCCP and RC women. Further work to investigate altered autonomic responses as a mechanism in CVaD is warranted.