Acetylcholine-Induced Atrial Fibrillation: The One-Night Stand

Background Persistent and paroxysmal atrial fibrillation (pAFib) are associated with a 3- to 5-fold increased stroke risk. Oral anticoagulation (OAC) mitigates this risk at the expense of increased bleeding events. Acetylcholine-induced AFib (AchAFib) occurs during coronary reactivity testing. A point that remains unclear is whether AchAFib carries the same thromboembolic risk as pAFib. We sought to determine the phenotypic profile and prognosis of AchAFib patients. Methods Patients were included if they underwent coronary reactivity testing with acetylcholine. Patients were excluded if they had persistent AFib, or if maximal dose acetylcholine was not administered for any reason other than AchAFib. Follow-up was obtained during clinic visits and by telephone. Results Among 567 patients, 42 (7.4%) suffered AchAFib. One had preceding pAFib treated with OAC and was excluded from the initial baseline characteristics analysis; the remaining 41 patients had no history of pAFib and did not receive OAC or experience subsequent pAFib or thromboembolic events during 918 +/- 556 days of follow-up. During long-term follow-up, 15 patients developed clinically apparent episodes of pAFib, none of whom experienced AchAFib. Compared to 42 patients with a history of preceding pAFib (n = 32) and/or subsequent pAFib (n = 15), the 41 patients with isolated AchAFib were significantly younger, and had significantly less left ventricular hypertrophy, smaller left atria, lower pulmonary pressures, and better exercise tolerance. Conclusions Isolated AchAFib may represent a benign event. Larger studies are required to confirm this conclusion.