ABSTRACT
Background: We have previously described the prognostic utility of QRS amplitude diminution (LoQRS) in predicting mortality and clinical decompensation in patients with COVID-19. However, whether and how COVID-19 vaccination status modulates risk prediction is not currently known. Objective: To assess any effect vaccination status may have on prevalence or risk prediction of LoQRS. Methods: We performed a retrospective analysis of patients admitted with laboratory confirmed COVID-19. Patients were excluded if the ECG was not acquired within 72 hrs of admission. Low QRS Amplitude (LoQRS) was defined by a composite of QRS amplitude <5mm in the limb leads or <10mm in the precordial leads (a composite of V1-V3 and V4-V6), or a ≥ 50% reduction in QRS amplitude. LoQRS was considered present even if found only in leads V1-V3 or V4-V6. Results: Among 3,365 patients, 11% were vaccinated and 89% were unvaccinated. LoQRS occurred in 30.9% of patients (33.5% of vaccinated patients and 30.5% in unvaccinated patients). Mortality occurred in 20.4% of patients without LoQRS compared to 30.2% in patients with LoQRS. The same pattern was seen in ICU admission, with 23.5% of patients without LoQRS being admitted to the ICU compared to 33.4% of patients with LoQRS. In multivariable models, LoQRS was independently associated with mortality and ICU admission regardless of vaccination status (or for mortality in unvaccinated patients: 1.24, 95% CI 1.03-1.49, P<0.01 vs 1.27 (95% CI 1.05-1.52, p<0.01). LoQRS also predicts ICU admission (OR 1.7, 95%CI 1.4-2.0) in unvaccinated patients vs. 1.73 (95%CI 1.5-2.1). In a survival analysis, vaccinated patients demonstrated improved mortality over unvaccinated counterparts, with a marked increase in mortality with, and stratification by, the presence of LoQRS in the unvaccinated. Conclusion: QRS amplitude on either the presenting or follow-up ECG independently predicts mortality and ICU admission in hospitalized patients with COVID-19 regardless of vaccination status. Patients who were vaccinated overall had better outcomes. [Formula presented]