Non-pharmacological provocation of coronary vasospasm. Experience with prolonged hyperventilation in the coronary...

Results are reported of prolonged hyperventilation as a provocation test in a consecutive series of six patients with a clinical diagnosis of Prinzmetal's variant angina (PVA) and a control series of eight patients. All the patients with PVA responded to the hyperventilation test (HVT) with significant ST deviation (five with elevation, one with depression) and typical anginal pain. None of the eight patients in the control series were positive responders. Sustained attacks of serious arrhythmias were recorded in one patient with PVA. Sensitivity to HVT showed circadian variations; the tests were positive only in the early morning at the time of the reported spontaneous attacks. Beta blockade changed a negative HVT response to a positive one in one case. Treatment with calcium channel blockers suppressed the positive response in all patients. After cessation of long-term treatment with calcium channel blockers, HVT suggested spontaneous remission in spasm tendency in three out of four patients with PVA from a previous series of 12 patients. It is concluded that HVT as a non-pharmacological provocation test may prove an effective and comparatively safe procedure with potential for controlling the efficacy of drug treatment and confirming spontaneous remission of vasospastic disease. Optimal facilities for resuscitation should be at hand during the test due to risk of provoking life-threatening arrhythmias.