Paroxysmal Atrial Fibrillation during Spasm Provocation Test with Acetylcholine: Clinical Characteristics of Patients...

Atrial fibrillation (AF) is a complication that occurs following a spasm provocation test (SPT) with acetylcholine (ACh). However, the characteristics of patients with AF remain unclear. Furthermore, the association of AF with the outcome of the coronary microvascular function test (CMFT) is unknown. This study aimed to evaluate whether patients with angina with non-obstructive coronary artery disease (ANOCA) who developed AF during SPT with ACh had any clinical characteristics. Additionally, we assessed the association of AF with the CMFT results.

We included 123 patients with ANOCA who underwent SPT and CMFT. We defined AF as AF during ACh provocation. The coronary arteries that demonstrated AF before CMFT were defined as AF vessels (n = 21) and those in sinus rhythm (SR) were defined as SR-1 vessels (n = 165). Vessels that were restored to sinus rhythm immediately following AF were defined as AF-SR vessels (n = 29) and those that remained in sinus rhythm for some time were defined as SR-2 vessels (n = 136). Coronary flow reserve (CFR) and index of microcirculatory resistance (IMR) were obtained, and CFR of <2.0 and/or IMR of ≥25 were diagnosed as coronary microvascular dysfunction (CMD).

Of the 123 patients, 31 (25%) had AF but with no characteristic patient background. CFR was significantly lower in AF vessels than in SR-1 vessels (p = 0.035) and IMR did not differ between the two groups (p = 0.918). A study of the three groups that included AF-SR vessels revealed that IMR tended to be lower in AF-SR vessels than in the SR-2 and AF vessels (p = 0.089), and that the frequency of IMR of ≥25 was significantly lower than in the other two groups (p = 0.016).

AF occurred in 25% of SPTs with ACh, but the predictive clinical context remains unclear. Our results indicated that AF may affect the outcome of the CMFT. Thus, decisions for CMD management should be made with caution in the presence of AF.