Prone and Supine 12-Lead ECG Comparisons: Implications for Cardiac Assessment During Prone Ventilation for COVID-19.

Objectives: This study sought to describe expected changes in a mirror-image prone electrocardiogram (ECG) compared with normal supine, including a range of cardiac conditions.
Background: Unwell COVID-19 patients are at risk of cardiac complications. Prone ventilation is recommended but poses practical challenges to acquisition of a 12-lead ECG. The effects of prone positioning on the ECG remain unknown.
Methods: 100 patients each underwent 3 ECGs: standard supine front (SF); prone position with precordial leads attached to front (PF); and prone with precordial leads attached to back in a mirror image to front (PB).
Results: Prone positioning was associated with QTc prolongation (PF 437 ± 32 ms vs. SF 432 ± 31 ms; p < 0.01; PB 436 ± 34 ms vs. SF 432 ± 31 ms; p = 0.02). In leads V ₁ to V ₃ on PB ECG, a qR morphology was present in 90% and changes in T-wave polarity in 84%. In patients with anterior ischemia, ST-segment changes in V ₁ to V ₃ on supine ECG were no longer visible on PB in 100% and replaced by an R-wave in V ₁ . Bundle branch block (BBB) remained detectable in 100% on PB, with left BBB appearing as right BBB on PB in 71% and QRS narrowing with qR in V ₁ for right BBB. ST-segment/T-wave changes in limb leads and arrhythmia detection were largely unaffected in PB.
Conclusions: As expected, the PB ECG is unreliable for the detection of anterior myocardial injury but remains useful for ST-segment/T-wave abnormalities in limb leads, BBB detection, and rhythm monitoring. The prone ECG is a useful screening tool with diagnostic utility in COVID-19 patients who require prone ventilation.
Competing Interests: Funding Support and Author Disclosures Dr. Chieng is supported by a cofunded National Health and Medical Research Council/ National Heart Foundation post-graduate scholarship. Dr. Kalman has received research and fellowship support from Medtronic and Biosense Webster. Prof. Kistler has received funding from Abbott Medical; and fellowship support from Biosense Webster. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.
(Copyright © 2021 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)