Procedural complications during intracoronary acetylcholine provocation testing in patients with cardiac arrest

Backgrounds In patients resuscitated from cardiac arrest, coronary vasospastic angina (VSA) is reportedly found in 3–10% as the underlying mechanism. In post-cardiac arrest patients with an unknown etiology, intracoronary acetylcholine (ACh) provocation testing may be indicated for evaluating coronary vasospasm. However, patients resuscitated from cardiac arrest are presumed to have an increased procedural complication risk of ACh provocation test, including cardiogenic shock and life-threatening arrhythmias, although the exact risk remains uncertain. Purpose The aim of this study was to evaluate adverse outcomes during ACh provocation testing between patients with and without resuscitated cardiac arrest. Methods From April 2012 to December 2024, a cohort of 1,127 patients who underwent ACh provocation testing at our institution were retrospectively analyzed. Patients were divided into two groups: those resuscitated from cardiac arrest (cardiac arrest group) and those without a history of cardiac arrest (no cardiac arrest group). In our institution, we routinely perform ACh provocation testing in post-resuscitation patients in stable conditions in an elective setting. ACh was injected in incremental doses of 20, 50, and 100 μg into the left coronary artery and 20 and 50 µg into the right coronary artery, but lower doses (2 or 10 μg) were allowed at the operators’ discretion. The primary endpoint was a composite of adverse events, defined as sustained ventricular tachycardia, ventricular fibrillation or temporary cardiogenic shock requiring vasopressor administration during ACh provocation testing. Results Of the 1,127 patients, 31 (2.8%) were those resuscitated from cardiac arrest. The median duration from cardiac arrest to ACh provocation testing in the cardiac arrest group was 13 days [interquartile range: 6–25 days]. Patients in the cardiac arrest group were significantly younger (56.5±15.0 vs. 63.9±12.8 years, p=0.002) and had a higher proportion of males (77.4% vs. 53.0%, p=0.009) than those in the no cardiac arrest group. The prevalence of current smoking was significantly higher in the cardiac arrest group (32.3% vs. 16.8%, p=0.049), while the left ventricular ejection fraction was significantly lower compared to the no cardiac arrest group (54.2±11.8% vs. 61.1±8.5%, p<0.001). The positive rate of the ACh provocation test was significantly higher in the cardiac arrest group (71.0% vs. 52.3%, p = 0.040). Notably, the incidence of adverse events during the test was also significantly higher in the cardiac arrest group (9.7% vs. 1.0%, p = 0.006). Conclusions ACh provocation testing in post-cardiac arrest patients was associated with a significantly higher incidence of intraprocedural adverse events. While ACh provocation testing may be valuable for evaluating an underlying etiology of cardiac arrest, the diagnostic procedures should be performed with caution, ensuring the immediate availability of defibrillation and vasopressor agents.