A comparison of clinical features of coronary artery spasm with and without thyrotoxicosis

Several reports have suggested that thyrotoxicosis may induce severe coronary artery spasm (CAS). However, there are few data regarding the differences in clinical characteristics of CAS with and without thyrotoxicosis. The aim of our study is to compare the clinical features of CAS with and without thyrotoxicosis.

We evaluated 430 consecutive patients with CAS [patients with thyrotoxicosis (N=32, group I) and those without (N=398, group II)] at a single institute between January 2001 and June 2011. We compared clinical presentations, angiographic findings, and adverse outcomes (a composite outcome of cardiac death, myocardial infarction, or rehospitalization due to cardiac cause) of both groups.

There was higher incidence of acute myocardial infarction at initial presentation in group I (15.6 vs. 5.8%, P=0.04). CAS with thyrotoxicosis was more diffuse (59.4 vs. 39.3%, P=0.03), more medically intractable (9.4 vs. 0%, P=0.001), and more frequently involved the left main vessel (25.0 vs.0.8%, P=0.001) than CAS without thyrotoxicosis. During the follow-up period (median 43 months), there were no significant differences between the two groups in terms of the risk of adverse outcomes (hazard ratio for CAS with thyrotoxicosis, 1.029; 95% confidence interval, 0.347-3.054).

Clinical and angiographic presentations of CAS with thyrotoxicosis were more severe than CAS without thyrotoxicosis, but clinical outcomes were similar in both groups. Optimal vasodilator therapy is essential for the management of CAS with thyrotoxicosis. Thyroid function test should be mandatory for all patients with CAS.