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 V1 to V3 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 V1 to V3 on supine ECG were no longer visible on PB in 100% and replaced by an R-wave in V1. 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 V1 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.

Determining the Optimal Dose of Adenosine for Unmasking Dormant Pulmonary Vein Conduction Following Atrial Fibrillation Ablation: Electrophysiological and Hemodynamic Assessment. DORMANT-AF Study.

INTRODUCTION: ELECTROPHYSIOLOGICAL AND HEMODYNAMIC ASSESSMENT. DORMANT-AF STUDY: The significance of adenosine induced dormant pulmonary vein (PV) conduction in atrial fibrillation (AF) ablation remains controversial. The optimal dose of adenosine to determine dormant PV conduction is yet to be systematically explored. METHODS AND RESULTS: ELECTROPHYSIOLOGICAL AND HEMODYNAMIC ASSESSMENT. DORMANT-AF STUDY: Consecutive patients undergoing index AF ablation received 3 adenosine doses (12, 18, and 24 mg) in a randomized blinded order, immediately after pulmonary vein isolation (PVI). Electrophysiological (PR prolongation, AV block (AVB) and PV reconnection) and hemodynamic (BP) parameters were measured. A total, 339 doses (113/dose) assessed 191 PVs in 50 patients (66% male, 72% PAF, 52% hypertensive). Dormant PV conduction occurred in 28% of patients (16.5% [32] of PVs). All cases were associated with AVB (AVB: PV reconnection vs. no PV reconnection 100% vs. 83%, P = 0.007). AVB occurred more frequently at 24 mg versus 12 mg (92% vs. 82%, P = 0.019) but not versus 18 mg (91%, P = 0.62). AVB duration progressed between 12 mg (12.0 ± 8.9 seconds), 18 mg (16.1 ± 9.1 seconds, P = 0.001), and 24 mg (19.0 ± 9.3 seconds, P < 0.001) doses. MBP fell further at 24 mg (ΔMBP: 27 ± 12 mmHg) and 18 mg (26 ± 13 mmHg) doses compared to 12 mg (22 ± 10 mmHg vs., P < 0.001). A significant reduction in AVB in patients >110 kg (65% vs. 91% in 70-110 kg group, P < 0.001) in response to adenosine was seen. CONCLUSION: ELECTROPHYSIOLOGICAL AND HEMODYNAMIC ASSESSMENT. DORMANT-AF STUDY: An adenosine dose producing AVB is required to unmask dormant PV conduction. AVB is significantly reduced in patients >110 kg. Weight and dosing variability may in part explain the conflicting results of studies evaluating the clinical utility of adenosine in PVI.