Long-term clinical outcomes according to first responsive dose of acetylcholine in patients with coronary artery spasm.

BACKGROUND

Coronary artery spasm (CAS) has become a focus of recent prognostic studies. However, research evaluating prognosis based on the initial dose of acetylcholine (ACH) at which patients first respond is lacking. This study aims to investigate long-term clinical outcomes according to the first responsive dose of ACH in patients with CAS.

METHODS

A total of 3783 patients with positive intracoronary provocation testing with ACH were categorized into three groups based on the dose at which they first exhibited a positive spasm response: A1 (20 μg), A2 (50 μg), and A3 (100 μg). The primary endpoint was major adverse cardiovascular events (MACE), and secondary endpoints included major adverse cardiovascular and cerebrovascular events (MACCE1) and MACCE1 with recurrent angina (MACCE2). Kaplan-Meier survival analysis and multivariate Cox regression were used to assess the relationship between the initial responsive dose and the clinical outcomes up to 10 years.

RESULTS

The prevalence of coronary artery stenosis was greater in the A1 group (61.6 %) compared to the A2 group (61.1 %) and the A3 group (56.8 %). The A1 group showed a higher incidence of MACE (10.8 %) compared to the A2 group (3.7 %) and the A3 group (3.5 %, P = 0.003). MACCE2 was also more frequent in the A1 group (38.2 %) than in the A2 group (28.9 %) and the A3 group (26.4 %, P = 0.036). Consistently, in multivariable Cox regression, the A1 group demonstrated a higher risk of both MACE (HR 2.43, 95 % CI 1.01-5.81, P = 0.047) and MACCE2 (HR 1.62, 95 % CI 1.09-2.39, P = 0.016) compared to the A3 group.

CONCLUSION

The initial responsive dose of ACH is a potential predictor of long-term clinical outcomes in patients with CAS. Patients who respond at lower doses may have a higher risk of adverse events, indicating the need for tailored therapeutic strategies based on ACH responsiveness.