Assessment of coronary vasomotor responses to acetylcholine in German and Japanese patients with epicardial coronary spasm—more similarities than differences?

Coronary spasm is an established cause for angina pectoris. Ethnic differences have been suggested among Asian compared to Caucasian patients regarding prevalence, gender distribution, and angiographic patterns of coronary spasm. The aim of this study was to compare contemporary German and Japanese patients with coronary spasm. Between 2011 and 2015, 149 patients with resting angina and unobstructed coronary arteries with acetylcholine-induced epicardial spasm were enrolled in Stuttgart, Germany (n = 69) and Sendai, Japan (n = 80). All patients underwent intracoronary acetylcholine testing according to a standardized protocol. Comprehensive analysis included type of spasm (focal/diffuse), dose of acetylcholine leading to spasm, and frequency of multivessel spasm. Patients in this study were 61 ± 11 years old, predominantly female (54%), and had normal left ventricular ejection fraction (73 ± 9%). Diffuse spasm was the most prevalent type of spasm (85%) whereas focal spasm was found in the remaining 15% of patients. 31% of patients had multivessel spasm. Comparing the German with the Japanese patients, distribution of spasm type (focal/diffuse, p = 0.19) and frequency of multivessel spasm (p = 0.22) were comparable. Moreover, when Japanese patients were compared with German patients and diffuse spasm with focal spasm patients, respectively, no significant differences were observed regarding the acetylcholine dose required to induce spasm (p = 0.078 and p = 0.46, respectively). In conclusion, diffuse epicardial coronary spasm is the most frequent finding among German and Japanese patients with resting angina, unobstructed coronary arteries, and epicardial spasm on acetylcholine testing. Japanese and German patients share several similarities including comparable types of spasm and frequency of multivessel spasm.