Alterations of autonomic nervous activity in recurrence of variant angina

Objective-To investigate whether autonomic nervous activity is involved in the recurrence of spontaneous coronary spasm in variant angina. Design-Retrospective analysis. Setting-Cardiology department of a university hospital. Patients-18 patient s with variant angina were divided into single attack group (SA; nine patie nts) and multiple attack group (MA; nine patients) according to the frequen cy of ischaemic episodes with ST segment elevation during 24 hour Holter mo nitoring. Methods-Heart rate variability indices were calculated using MemCalc method , which is a combination of the maximum entropy method for spectral analysi s and the non-linear least squares method for fitting analysis, at 30 secon d intervals for second periods, from 40 minutes before the attack to 30 min utes after the attack. High frequency (HF; 0.04-0.15 Hz) was defined as a m arker of parasympathetic activity, and the ratio of low frequency (LF; 0.15 -0.40 Hz) to high frequency (LF/HF) as an indicator of sympathetic activity . The averaged value during the 40 to 30 minute period before an attack was defined as the baseline. Results-Compared with baseline, the HF component decreased in both groups a t two minutes before the attack (p < 0.01), and the LF/HF ratio decreased a t three minutes before the attack (p < 0.01). The baseline LF/HF was lower in the MA group than in the SA group (p < 0.01). Conclusions-A reduction of sympathetic activity may play a key role in dete rmining the recurrence of transient ischaemic events caused by spontaneous coronary spasm in patients with variant angina.