Day-to-day variability of the long-term fractal component of heart rate variability (β) and the effect of an antianginal agent in patients with silent myocardial ischemia

Abstract The deterioration of the long-term fractal component of heart rate variability (β) is reported in patients with organic heart disease. To examine the day-to-day variability of β and to study the effects of nipradilol (NIP), an antianginal agent, on β in patients with coronary artery disease (CAD), we performed 24-hour ambulatory ECG (AECG) in 24 patients with silent myocardial ischemia (SMI) and obtained the conventional frequency domain heart rate variability (HRV) indices and β using the MemCalc system. Patients were divided into two groups: group I consisted of 10 patients (64±5 years of age) for the assessment of the day-to-day variability of β; group II comprised 14 patients (60±6 years of age) for evaluation of the effect of NIP (3 mg b.i.d). In group I, AECG was repeated twice a week, while AECG was recorded before NIP treatment (placebo) and on the last day of the 4-week NIP treatment in group II. In group I, there was significant correlation between the values of β on day 1 and day 2 ( r =0.79, p