Effects of bisoprolol on the circadian distribution of silent myocardial ischemia and frequency domain parameters of heart rate variability

The autonomic nervous system is believed to play an important role in the occurrence of silent myocardial ischemia (SMI). To investigate the effect of bisoprolol on the circadian distribution of SMI and heart rate variability (HRV) we studied 5 patients with/> 4 episodes of SMI during 48 h Holter registration after a placebo run-in period. Patients were treated 4 weeks with bisoprolol 10 mg once daily. Spectral analysis of HRV was performed using a FFT algorithm, resulting in low frequency (LF, 0.04-0.15 Hz), high frequency components (HF, 0.15-0.40 Hz) and L F / H F ratio.