key: cord-0711729-ddb6klqw authors: Chieng, David; Sugumar, Hariharan; Kaye, David; Azzopardi, Sonia; Vizi, Donna; Rossi, Erina; Voskoboinik, Aleksandr; Prabhu, Sandeep; Ling, Liang-Han; Lee, Geoffrey; Kalman, Jonathan M.; Kistler, Peter M. title: Prone and Supine 12-Lead ECG Comparisons: Implications for Cardiac Assessment During Prone Ventilation for COVID-19 date: 2021-06-30 journal: JACC Clin Electrophysiol DOI: 10.1016/j.jacep.2021.04.011 sha: 7aa3edb18315b557bcab504509cbc4a23d13857d doc_id: 711729 cord_uid: ddb6klqw 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. morbidity and mortality (3) . Myocardial injury had been observed in 36% of hospitalized COVID-19 patients (4) . Cardiac arrhythmias have also been reported (5) . In view of this, cardiac monitoring with telemetry and/or electrocardiogram (ECG) is recommended in hospitalized COVID-19 patients (6) . Furthermore, cardiac monitoring is important because pharmacotherapy may be proarrhythmic. In particular, hydroxychloroquine and azithromycin are known to prolong the QT interval, with the risk of torsade de pointes heightened by concomitant illness and polypharmacy (7) . In COVID-19 patients with hypoxic respiratory failure, early intubation and ventilation have been recommended in society guidelines. Early proning has become an important ventilation strategy that improves oxygenation (8) . A prone ECG avoids repositioning patients for a 12-lead ECG, which may result in oxygen desaturation and is labor-intensive. Although prone positioning is useful, the impact on the 12-lead ECG is relatively unknown. ECG leads V 7 to V 9 , as an extension of precordial leads V 1 to V 6 , have long existed to diagnose a posterior infarct. However, the utility of a complete posterior ECG as a mirror image to the usual supine precordial V 1 to V 6 arrangement has not been well described. Smaller studies have reported expected differences in ECG appearances in a supine versus prone position, although the studies were confined to healthy volunteers (9, 10) . As the COVID-19 pandemic continues to challenge health care systems, a prone ventilation strategy is increasingly used. The 12-lead ECG is the cornerstone of cardiac assessment and provides an inexpensive, repeatable assessment for cardiac complications. The present prospective study was designed to: 1) describe expected differences in the 12-lead ECG in the prone position compared with the supine and; 2) determine the usefulness of the prone ECG in detecting myocardial injury and abnormalities in rhythm and conduction. Table 1 . In the PF position, the ECG was largely unchanged aside from a delay in precordial R-wave transition by $1 V lead (n ¼ 32, 91%). In a PB position, changes in QRS morphology were seen in all patients, confined to the precordial leads only. An initial Q wave was present in leads V 1 to V 3 in 78 patients (90%), followed by low-amplitude R waves across the precordial leads were seen in the inferior leads (n ¼ 28), followed by Figure 3) . In a PF position, 10 of 37 Values are mean AE SD or n (%) except as noted. There is an increasing body of literature on COVID-19 disease and associated cardiac complications. Elevated cardiac troponin-I levels has been reported in 36% of patients, consistent with myocardial injury (4). Recent studies have also demonstrated the feasibility of proning in nonintubated patients (18, 19) . Oxygenation substantially improved from supine to prone positioning (19) . Importantly, early prone positioning was associated with better maintenance of oxygenation during hospitalization. These findings are substantial because they show that proning in nonintubated patients can be safely performed on wards outside of the intensive care unit (18) . A large meta-trial is currently underway looking at the efficacy of awake prone positioning in COVID-19 patients (20). Under such circumstances, the ability to perform and interpret a 12-lead ECG in the prone position will avoid repositioning patients with the potential for respiratory deterioration. 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