Quantitative autonomic testing after recovery from acute COVID-19 infection: comparison with findings in controls and individuals with neurogenic autonomic dysfunction

Abstract

Abstract Background/Introduction Cardiovascular autonomic dysfunction (CvAD) is believed to contribute to the persistence of troublesome symptoms following apparent recovery from an acute COVID-19 infection. Common complaints in this setting include cognitive impairment (‘brain fog’), fatigue, and both postural and exertional intolerance with a sensation of excessive rapid heart beating. However, while the occurrence of CvAD post-acute COVID-19 has been widely recognized, its quantitative assessment remains largely unexplored. Purpose The purpose of this study was to determine whether quantitative cardiovascular autonomic testing in post-acute COVID-19 patients differ from findings in Controls and are more similar to individuals with Neurogenic CvAD, such as those with Pure Autonomic Failure. Methods Quantitative autonomic testing was prospectively undertaken in two patient groups: post-acute COVID-19 and Neurogenic CvAD patients, and in control subjects. Acute COVID-19 was documented by the nasopharyngeal PCR method and all affected patients had recovered at least 1 week prior to their autonomic study. Neurogenic CvAD patients were studied as part of their diagnostic evaluation, and none had a COVID-19 infection prior to their study. Measurements included i) heart rate (HR) and blood pressure (BP) responses during active standing (AS), ii) time to BP nadir and time to BP recovery during AS, iii) Valsalva ratio (VR), and iv) respiratory sinus arrhythmia (RSA). The unpaired student t-test and Mann Whitney U test were used to analyze normally and non-normally distributed data, respectively, between post-acute COVID patients and the Control and Neurogenic CvAD patients. All variables were continuous and presented as means with corresponding standard deviations (SD) when normally distributed or interquartile ranges (IQR) when non-normally distributed. A p-value of <0.05 was considered statistically significant. Results Post-acute COVID-19 patients (N=55, 83.6% female) and Controls (N=82, 86.6% female) were of similar age (39 [IQR 27.3, 49.2] vs. 33 [IQR 21.4, 40.0] years, respectively, p=0.034). Neurogenic CvAD patients (N=27, 51.9% female) were older (68 [IQR 62.9, 74.3], p<0.00001). The main findings (Table 1, mean [SD]) indicate that post-acute COVID-19 patients exhibited HR and BP responses during AS similar to the Control group; on the other hand, average VR, maximum systolic BP drop during AS, and maximum HR increase during AS in COVID-19 patients trended towards findings in Neurogenic CvAD patients. Conclusion Recovered post-acute COVID-19 patients referred for autonomic dysfunction evaluation due to persisting symptoms exhibit autonomic testing findings similar to control subjects but trending towards observations in neurogenic CvAD.