Impaired Parasympathetic Cardiac Modulation In Long-COVID Postural Tachycardia Syndrome

ABSTRACT

About 1 out of 10 patients infected with Sars-CoV2 have persistent symptoms beyond 4 weeks and some of them meet diagnostic criteria for postural tachycardia syndrome (Long-COVID POTS). The pathophysiology of Long-COVID POTS is unknown, but autonomic dysfunction may play a role. We hypothesize Long-COVID POTS patients have impaired cardiovascular autonomic reflexes and cardiac sympathovagal balance. We conducted a case-control study with patients recruited from the Vanderbilt Autonomic Dysfunction Center and an historical population of healthy controls. Hemodynamic parameters were measured before and during 75degree head up tilt. Supine ECG and finger blood pressure were continuously measured for spontaneous heart rate variability analysis. The Low Frequency (0.04-0.15Hz, LF ) and High Frequency (0.15-0.4 Hz, HF ) oscillatory modulations of sino-atrial node discharge were computed. We included 14 Long-COVID POTS patients and 15 controls matched by age (34+/-11 vs 28+/-7;p=0.09) and BMI (26.1+/-5.3 vs 23.0+/-2.6;p=0.06). As expected, the orthostatic HR increase was higher in Long-COVID POTS compared to controls (40+/-18 vs 21+/-1, p<0.05). Spectral analysis of heart rate variability in 9 patients and 15 controls (Figure) showed that Long-COVID POTS had reduced HF (363+/-420 vs 933+/-1000 ms ;p<0.05) and similar LF (798+/-596 //////////vs 962+/-1075 ms ;p=0.68), resulting in a greater LF/HF ratio (3.7+/-2.9 vs 1.4+/-1.3;p<0.05). Patients with Long-COVID POTS have reduced markers of cardiovagal modulation, but normal cardiac sympathetic activation. Our results suggest that parasympathetic dysfunction contributes to the pathophysiology of Long-COVID POTS.