Vasospastic angina: control of disease activity and efficacy of drug treatment using the prolonged hyperventilation test.

Sixteen consecutive patients with vasospastic angina underwent a control provocation test in the coronary care unit or the cardiac catheterization laboratory in order to evaluate the disease activity and the efficacy of long-term calcium antagonist treatment. In patients without angina at rest, the prolonged hyperventilation test was negative in 10/10 patients on calcium antagonist treatment (group A + B) and in 4/5 patients without medication (group C). The test was positive in 1/1 patient with angina at rest without medication (group D). However, the test provoked vasospastic angina in 1/5 patients who were asymptomatic without medication. In both the latter patients the prolonged hyperventilation test became negative after the restart of calcium antagonist treatment. During a mean follow-up period of 18 months (range 16-19) after the control hyperventilation test, no relapse of angina at rest, arrhythmias, syncopes, deaths or myocardial infarctions were registered. Thus, a negative test is compatible with low disease activity and/or efficacy of calcium antagonist treatment. Further, the test may reveal a subclinical tendency to coronary artery spasm.