For a study, researchers investigated testing safety and subgroup variations in procedural risks depending on ethnicity, diagnostic criteria, and provocation methods.

In November 2021, PubMed and Embase were searched for original papers describing procedural problems linked with intracoronary ACh injection. The main outcome was the pooled estimate of the incidence of serious complications such as mortality, myocardial infarction, ventricular tachycardia/fibrillation, and shock.

The meta-analysis comprised 16 trials with a total of 12,585 patients. Without any death reports, the total pooled estimate of the incidence of significant complications was 0.5% (95% CI: 0.0% -1.3%). Exploratory subgroup analyses revealed that the pooled incidence of major complications was significantly higher in studies that used the contemporary epicardial spasm diagnosis criteria of less than or equal to 90% diameter reduction (1.0%; 95% CI: 0.3%-2.0%) but significantly lower in Western populations (0.0%; 95% CI: 0.0%-0.45%). The frequency of severe sequelae and the rate of positive epicardial spasms were comparable for provocation procedures utilizing the maximal ACh dosages of 100 μg and 200 μg.

Intracoronary ACh injection is a safe method for the modern diagnosis of epicardial and microvascular spasms. Furthermore, excellent safety records have been documented in Western populations presenting with myocardial ischemia and/or infarction via nonobstructive coronary arteries. The study will aid in standardizing ACh testing to enhance clinical diagnosis and assure procedural safety.