Abnormal heart rate control in vasospastic angina: effects of calcium antagonists.

We examined the effects of administration of calcium antagonists on the heart rate response to treadmill exercise in 11 patients with vasospastic angina and 8 healthy young volunteers. The exercise test was performed by walking on a treadmill at a constant speed and grade according to a scheme of pseudo-randomized sequence for 19 min. The dynamic property of heart rate response to exercise was evaluated by using a frequency analytic procedure. The exercise test was also studied in 21 age-matched normal controls without drug administration. Administration of calcium antagonists revealed no significant effects on heart rate and blood pressure at rest in young healthy subjects or in patients with vasospastic angina. Young volunteers showed the same normal properties of heart rate response to exercise before and after calcium antagonists. Vasospastic angina showed abnormal heart rate response to exercise and revealed characteristically different transfer function from that in normal controls. These characteristics were not affected by treatment with calcium antagonists except for a slight, uniform decrease of gain of the system over the whole frequency range. Accordingly, the present exercise test can feasibly be used in the diagnosis and management of vasospastic angina even when calcium antagonists are administered to the patients.