Autonomic nervous system activity before and during episodes of myocardialischemia in patients with stable coronary artery disease during daily life

Spectral analysis of heart rate variability(HRV) was used to assess changes in the autonomic nervous system (ANS) 10 minutes before, during, and 10 mi nutes after 110 ischemic episodes (IEs) in 38 patients (25 men, age 61 +/- 10 years) with stable coronary artery disease. In 26 of 77 diurnal IEs [07: 00-22:59] there were no changes in the spectral indexes (LF and HF) during the study period. In the remainder there was an increase in the LF:HF ratio due to HF withdrawal that started before the onset of the IE. All 33 noctu rnal episodes also showed an increase in the LF:HF ratio, which was due not only to HF withdrawal, but also to a simultaneous increase in LF. Although it is not the only cause, the ANS plays a significant role in triggering I fs during daily life in patients with stable coronary artery disease. The c ommon factor in all such episodes is a gradual withdrawal of parasympatheti c tone.