749-4 Role of Autonomic Tone in the Induction of Coronary Spasm in Patients with Variant Angina with or without Obstructive Coronary Stenoses

Abstract

To evaluate the role of autonomic tone in the induction of coronary spasm, we analysed time- and frequency-domain indexes of heart rate variability (HRV) preceding episodes of 5T elevation (5Te) detected on Holter monitoring in 23 patients (17 men, age 59 ± 12 yrs) with variant angina. Only 5Te episodes lasting ≥ 3 minutes and with no 5T changes in the previous 40 min. were selected for the analysis. Of a total of 239 5Te episodes, 93(39%, 3.5 ± 3 episodeslpt, range 1–12) fulfilled the inclusion criteria. HRV indexes were calculated on 2-minute intervals, centered at 3D, 15, 5 and 1 minutes before 5Te. The HRV changes were compared in 50 episodes of 10 pts with no significant stenosis (Group 1) and in 43 episodes of 13 pts with significant stenoses (> 50%) at coronary angiography. HRV indexes showed no change from 30 to 15 and 5 minutes before 5Te in both groups. At 1 minute before 5Te, HRV analysis showed relevant changes in several specific indexes of vagal activity in group 1, while a significant reduction was observed onlyfor HF in group 2. HRV values observed 30’ and l’ before (8) 5Te are summarized in the table. Group 1 Group 2 30’B STe l’B STe 30’B STe l’B STe RR (msec) 957 ± 168 937 ± 171 842 ± 196 826 ± 175 r-MSSD (msec) 33.4 ± 23 26.4 ± 18 * 28.0 ± 14 29.4 ± 14 pNN50(%) 9.9 ± 14 7.6 ± 13 ‡ 10.8 ± 12 10.2 ± 10 LF (msec 2 ) 396 ± 225 256 ± 49 734 ± 484 566 ± 256 HF (msec 2 ) 292 ± 144 178 ± 81 ‡ 269 ± 81 185 ± 36 * * p < 0.01 ‡ p <‡0.05 Thus, our data show that a reduction in vagal activity precedes ischemic episodes in patients with variant angina, suggesting that it may facilitate the induction of coronary spasm. The degree of vagal withdrawal, however, is much higher in pts with normal coronary arteries, in whom a greater degree of coronary vasoconstriction is likely needed to cause ischemia in the absence of critical coronary stenoses.