Behavior of the PR interval with increasing heart rate in patients with COVID-19

Abstract

Background: Myriad manifestations of cardiovascular involvement have been described in patients with coronavirus disease 2019 (COVID-19), but there have been no reports of COVID-19 affecting the cardiac conduction system. The PR interval on the electrocardiogram (ECG) normally shortens with increasing heart rate (HR). The case of a patient with COVID-19 manifesting Mobitz type 1 atrioventricular (AV) block that normalized as the patient's condition improved prompted us to investigate PR interval behavior in patients with COVID-19.

Objective: The purpose of this study was to characterize PR interval behavior in hospitalized patients with COVID-19 and to correlate that behavior with clinical outcomes.

Methods: This study was a cross-sectional cohort analysis of confirmed COVID-19 cases (March 26, 2020, to April 25, 2020). We reviewed pre-COVID-19 and COVID-19 ECGs to characterize AV conduction by calculating the PR interval to HR (PR:HR) slope. Clinical endpoints were death or need for endotracheal intubation.

Results: ECGs from 75 patients (246 pre-COVID-19 ECGs and 246 COVID-19 ECGs) were analyzed for PR:HR slope. Of these patients, 38 (50.7%) showed the expected PR interval shortening with increasing HR (negative PR:HR slope), whereas 37 (49.3%) showed either no change (8 with PR:HR slope = 0) or paradoxical PR interval prolongation (29 with positive PR:HR slope) with increasing HR. Patients without PR interval shortening were more likely to die (11/37 [29.7%] vs 3/38 [7.9%]; P = .019) or require endotracheal intubation (16/37 [43.2%] vs 8/38 [21.1%]; P = .05) compared to patients with PR interval shortening.

Conclusion: Half of patients with COVID-19 showed abnormal PR interval behavior (paradoxical prolongation or lack of shortening) with increasing HR. This finding was associated with increased risk of death and need for endotracheal intubation.

Keywords: COVID-19; Coronavirus; Electrocardiogram; PR Interval; SARs-CoV-2.

Graphical abstract

Figure 1

Example of PR interval measurement. Superimposed median format used for manual PR interval measurements on electrocardiograms with heart rate >100 bpm or with overtly incorrect automated PR interval measurements. This format displays the superimposed 6 limb leads (synchronized to QRS onset) at twice paper speed and gain, and utilizes a nonlinear digital filtering technique to minimize artifact. Electronic on-screen calipers are used for precise PR interval measurement.

Figure 2

Flow diagram for patient inclusion. Screening was based on availability of pre–COVID-19 and COVID-19 electrocardiograms in order to allow PR:HR slope calculation. After meeting inclusion and exclusion criteria, there were 75 patients with 514 ECGs for analysis of PR:HR slopes. COVID-19 = coronavirus 2019; HR = heart rate; MRN = medical record number.