ST-segment elevation and ventricular fibrillation without coronary spasm by intracoronary injection of acetylcholine and/or ergonovine maleate in patients with Brugada syndrome

Objectives The study examined whether patients with Brugada syndrome are sensitive to vagal stimulation or ischemia. Background Experimental studies have suggested that a prominent transient outward current (Ito)-mediated action potential notch and a subsequent loss of the action potential dome in the epicardium, but not in the endocardium, give rise to ST-segment elevation and subsequent ventricular fibrillation (VF). Methods We evaluated the frequency of coronary spasm, augmentation (≥0.1 mV) of ST-segment elevation in leads V1 to V3, and induction of VF by intracoronary injection of acetylcholine (ACh) and/or ergonovine maleate (EM) in 27 symptomatic patients with Brugada syndrome and 30 control subjects. Results The coronary spasm was induced in 3 (11%) of the 27 patients with Brugada syndrome and in 13 (43%) of the 30 control subjects. ST-segment elevation was augmented by 11 (33%) of the 33 right coronary injections (ACh: 6/11 [55%]; EM: 5/22 [23%]), without coronary spasm, but not by any of the left coronary injections in patients with Brugada syndrome. Ventricular fibrillation was induced by 3 (9%) of the 33 right coronary injections (ACh: 2/11 [18%]; EM: 1/22 [5%]), but not by any of the left coronary injections. In contrast, neither ST-segment elevation nor VF was observed in any of the control subjects. Conclusions Our results support the hypothesis that mild ischemia and vagal influences act additively or synergistically with the substrate responsible for the Brugada syndrome to elevate the ST- segment and precipitate VF. These observations suggest that Brugada patients may be at a higher risk for ischemia-related sudden death.