Successful brachytherapy of coronary vasospasm

Coronary artery spasm: Current knowledge and residual uncertainties

Myocardial ischaemia results from a direct mismatch between oxygen supply and demand, commonly arising as a result of coronary atherosclerosis, microvascular dysfunction or acute thrombosis and luminal obstruction. However, transient ischaemia may also occur due to coronary spasm leading to acute and unexpected myocardial ischaemia without obvious visible coronary pathology. Aside from symptoms of chest pain, coronary spasm can cause infarction, LV impairment, promote life threatening arrhythmias and ultimately sudden cardiac death. While therapeutic options are available, controversies exist around diagnosis, pathology, management and prognosis. This review summarises some of the common questions in this area. In particular we explore and discuss the available evidence for the pharmacological treatment of coronary spasm, and strategies for identification and management of very high risk patients to try and reduce the incidence of sudden premature death.

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Myocardial ischaemia results from a mismatch between oxygen supply and demand.

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Spasm might lead to myocardial ischaemia without visible coronary pathology.

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Coronary spasm can cause infarction, LV impairment and sudden cardiac death.

Disruption of coronary vasomotor function: the coronary spasm syndrome

Abnormal coronary vasoconstriction, or coronary spasm, can be the result of several factors, including local and neuroendocrine aberrations. It can manifest clinically as a coronary syndrome and plays an important role in the genesis of myocardial ischemia. Over the past half century, coronary angiography allowed the in vivo demonstration of spasm in patients who fit the initial clinical description of the condition as reported by Prinzmetal et al. Several clinical, basic, and more recently, genetic studies have provided insight into the pathogenesis, manifestations, and therapy of this condition. It is not uncommonly encountered in patients with coronary syndromes and absence of clearly pathologic lesions on angiography. Provocation tests utilizing pharmacologic and nonpharmacologic stimuli combined with imaging (echocardiography or coronary angiography) can help make the correct diagnosis. The use of calcium channel blockers and long-acting nitrates is currently considered standard of care and the overall prognosis appears to be good. The recent discovery of genetic abnormalities predisposing to abnormal spasm of the coronaries has stimulated interest in the development of targeted therapies for the management of this condition.

Is there a role for provocation testing to diagnose coronary artery spasm?

Spontaneous coronary artery spasm is an important cause of morbidity both in patients with coronary artery disease and in those with variant angina. A number of pharmacological agents have been identified which can provoke coronary artery spasm in susceptible patients. The role of provocation testing in the clinical diagnosis of coronary spasm is controversial. This is reflected by variations in the clinical use of provocation testing between specialist cardiac centres. Provocation testing appears to be a sensitive method of identifying patients with variant angina and active disease but such patients can often be diagnosed clinically. The specificity is less clear. There is little evidence that altering patient therapy on the basis of a positive test modifies prognosis. There may be a role for provocation testing in rare patients with refractory disease to identify a target site for coronary stenting. A more widespread use of these tests in patients with undiagnosed chest pain syndromes would not currently be recommended.

Brachytherapy: potential therapy for refractory coronary spasm

OBJECTIVES

We sought to demonstrate that brachytherapy reduces coronary spasm in refractory and highly symptomatic variant angina.

BACKGROUND

In some patients with variant angina due to extensive vasoconstriction, intensive drug therapy fails to sufficiently relieve symptoms.

METHODS

In 18 patients with frequent angina episodes despite triple anti-anginal therapy, coronary spasm was induced by intracoronary acetylcholine (ACh) infusion. Five patients had spasm in a second vessel. Intracoronary radiation (20 Gy) was applied to vasospastic segments using a beta-emitting ((32)P) wire source centered within a Galileo balloon. Parameters of vessel function before and after brachytherapy were investigated.

RESULTS

Before brachytherapy, artery diameters decreased (p < 0.0001) from 2.8 +/- 0.4 mm to 1.0 +/- 0.4 mm for the first vessels and from 3.1 +/- 0.3 mm to 1.0 +/- 0.2 mm for the second vessels. After brachytherapy (143 +/- 106 and 80 +/- 52 days for first and second vessels, respectively), ACh-induced vasoconstriction was significantly reduced. The ACh-induced changes in artery diameter before and after brachytherapy were -1.5 +/- 0.5 mm and -0.5 +/- 0.3 mm (p < 0.0001) for the first vessels and -1.4 +/- 0.3 mm and -0.4 +/- 0.2 mm (p < 0.01) for the second vessels, respectively. In non-irradiated spastic vessels, ACh-induced vasoconstriction remained unchanged (e.g., -1.7 +/- 0.6 mm, -1.6 +/- 0.3 mm, and -1.5 +/- 0.5 mm for second vessels, at first investigation, first follow-up, and immediately before brachytherapy, respectively). Angina frequency decreased from 15.6 +/- 6.0 to 2.2 +/- 2.4 angina episodes/week (p < 0.001) in treated patients.

CONCLUSIONS

Brachytherapy is a potential therapy in patients with highly symptomatic variant angina.