PO-701-03 ANATOMICAL CONSIDERATIONS AND CLINICAL INTERPRETATION OF PRONE 12-LEAD ECG: INSIGHTS FROM A MULTICENTER PROSPECTIVE STUDY

Abstract

Prone positioning increases lung recruitment and improves oxygenation in acute respiratory distress syndrome (ARDS) and has been used for decades in spinal and orthopedic surgery. This study aims to provide guidance for the clinical interpretation of ECGs in prone position and to establish the electroanatomic explanations for the possible differences that may be observed. ECGs in supine, prone posterior and prone anterior position were prospectively examined on 85 subjects. Comparisons of ECG parameters between these positions were performed. Computed tomography (CT) scans were performed in both positions to determine possible electroanatomic etiologies for prone-associated ECG changes. There were significant differences in QRS amplitude in leads V1-V5 between supine and prone positions: V1: 1.08mV vs. 0.3mV, p<0.0001; V2: 1.61mV vs. 0.35mV, p<0.0001; V3: 1.62mV vs. 0.48mV, p<0.0001; V4: 1.65mV vs 0.63, p<0.0001 and V5: 1.41mV vs. 0.95mV, p<0.0001; respectively. Q waves were more frequently observed in prone posterior position than in supine position (V1: 74.5% vs. 10.6%, p<0.001; V2: 23.5% vs. 1.2%, p<0.001, respectively). Flat and inverted T waves were more common in posterior leads (V1: 98% vs. 66%, p<0.001; V2: 96% vs. 8%, p<0.001; V3: 45% vs. 7%, p<0.001; V4: 25% vs. 4%, p<0.001). A Pearson’s correlation analysis of the 3D-CT reconstructions measurements showed a significant inverse correlation between QRS amplitude and the distance from the center of the heart to the estimated lead positions. (V1: r=-0.816, p=0.0001; V2: r=-0.805, p=0.0002; V3: r=-0.77, p=0.0005; V4: r=-0.692, p=0.003; V5: r=-0.0422, p=0.10; V6: r=-0.02, p=0.95). Prone position can be used as an alternative of supine ECG in ARDS and healthy patients. In prone position ECGs, low QRS amplitude should not be misinterpreted as low voltage conditions neither should Q-waves in V1-V2 and abnormal T-waves in V1-V4 be considered anteroseptal myocardial infarction.