Effect of Diltiazem on Sympathetic Hyperactivity in Patients With Vasospastic Angina as Assessed by Spectral Analysis of Arterial Pressure and Heart Rate Variability

The autonomic nervous system importantly regulates coronary arterial tone and vascular resistance. To evaluate a role of autonomic nervous activity and the effects of calcium antagonist in patients with vasospastic angina (VSA), 13 VSA patients with patent coronary arteries (58 ± 8 years) and 8 normal subjects (58 ± 12 years) were studied. Arterial pressure and electrocardiogram were continuously recorded with the patient in a supine position under controlled respiration (0.2 Hz). Low-frequency (LF) and high-frequency (HF) components of the beat-to-beat variabilities of systolic arterial pressure and RR interval were then estimated by autoregressive power spectral analysis. The LF power (normalized unit) of both systolic arterial pressure (0.53 ± 0.17 vs 0.30 ± 0.17, p <0.01) and RR variabilities (0.51 ± 0.20 vs 0.31 ± 0.16, p <0.05) in patients with VSA were greater than that in normal subjects. There was no significant difference in the HF power. Seven patients with VSA who were treated with diltiazem (60 to 200 mg/day) had normalized LF power (normalized unit) of both systolic arterial pressure (0.62 ± 0.12 vs 0.33 ± 0.16, p <0.01) and RR variabilities (0.55 ± 0.23 vs 0.36 ± 0.14, p <0.05), together with clinical improvement. An increased sympathetic vasomotor tone and cardiac sympathetic predominance may play an important role in patients with VSA. Diltiazem improves these sympathetic hyperactivities.