Large vessel coronary vasospasm: Diagnosis, natural history and treatment

Abstract

The diagnosis of coronary artery spasm is confirmed by angiography, for example, change in caliber of the coronary arteries plus evidence of ischemia. The prevalence and contribution of coronary artery spasm in the individual patient with symptoms of ischemic heart disease is not known and depends on how the condition is defined. The prognosis of patients with coronary artery spasm appears to depend on the presence or absence of severe coronary atherosclerosis, that is, those with severe disease have a worse prognosis. Nitrates should be used to initiate therapy in all patients with this problem. Intravenous nitrates have proven useful in patients whose symptoms are difficult to control and who require hospitalization. β blockers used alone may be detrimental in patients with coronary artery spasm, but studies supporting the detrimental effects are few. The combination of nitrates, β blockers and nifedipine has proved effective therapy for many patients with recurrent angina at rest, possibly related to coronary artery spasm. Several open-label and double-blind placebo control trials have shown that all of the calcium antagonists are effective short-term agents for patients with proven coronary artery spasm. When nifedipine was compared with isosorbide dinitrate in a randomized crossover, double-blind trial in patients with coronary artery spasm, both drugs were shown to be efficacious and neither was superior. The traditional α-blocking agents have not been shown to be an effective therapy, but a recent study of prazosin, a selective α blocker, revealed excellent results in patients whose conditions were resistant to therapy with traditional calcium blockers, β blockers and, in 1 case, phenoxybenzamine. Another study, however, showed no beneficial effect, α-β blockers, anticholinergic drugs, aspirin and prostacylin have not been shown to be effective treatment for coronary artery spasm. In patients with “refractory coronary artery spasm” it may be necessary to use intracoronary nitroglycerin, combinations of calcium antagonist alone or with nitrates, or prazosin therapy to control symptoms. Although the reason is not clear, a few cases have responded to therapy with intraaortic balloon counter pulsation. Coronary artery bypass surgery with and without denervation procedures is effective in many patients with obvious obstructive coronary stenosis, in addition to coronary artery spasm related to the underlying coronary lesions. However, results are not as good in those patients as in patients with fixed coronary stenosis and no evidence of coronary artery spasm.