Abstract 592: Serum Endothelin-1 Level at the Onset of Ischemic Ventricular Fibrillation Predicts Resuscitation Outcome
Endogenous vasopressors, including endothelin-1 (ET-1), have been shown to be elevated in patients following resuscitation from out-of-hospital cardiac arrest and are likely a physiologic response to global ischemia. The importance of ET-1 in the setting of arrest and resuscitation has not been established. Prior work has demonstrated that ET-1 increases significantly after coronary occlusion. The purpose of this study was assess changes in ET-1 following induction of ischemia and ventricular fibrillation (VF). VF was induced in 30 anesthetized and instrumented swine by balloon occlusion of the left anterior descending coronary artery (LAD). Blood was collected from the right atrium at baseline and at 5 minutes intervals following LAD occlusion until VF occurred. After 7 min of VF, resuscitation was attempted in accordance with guidelines. ET-1 and matrix metalloproteinase-9 (MMP9), a measure of infarct size, were measured using ELISA. ET-1 and MMP-9 levels increased significantly from baseline within 15 min of occlusion of the LAD. Differences between animals achieving restoration of spontaneous circulation (ROSC) and those that did not are shown in the table (mean ± SD). Animals that could not be resuscitated had a higher ET-1 (p = 0.031) at VF onset but similar ischemia time (time to VF) and MMP-9, reflecting infarct size. An ET-1 level > 4 pg/ml had a likelihood ratio of 4 for predicting resuscitation failure. Elevated levels of ET-1 during acute ischemia predict resuscitation failure independent of the time to VF. Failure may be due to the known of effect of ET-1 on coronary vascular resistance or ventricular compliance, resulting in early ischemic contracture.