Baroreflex-dependent Cardiovascular Autonomic Reactivity is Deranged in Young Adult Mild COVID-19 Survivors.

BACKGROUND: COVID-19 has subacute as well as long-term effects defined as long COVID on multiple organ systems. Emerging literature suggests long-term effects of COVID-19 on the autonomic nervous system in survivors, the mechanistic basis of which is currently not delineated. PURPOSE: The study aimed to assess the cardiovascular autonomic functions in mild COVID-19 survivors and compare them with age- and sex-matched healthy controls. METHODS: We recruited 34 young adult mild COVID-19 survivors. Autonomic function was assessed by cardiovascular autonomic reactivity tests at least 1 month after clinical recovery from acute COVID-19 infection. The responses were compared with those of 34 age- and sex-matched pre-COVID era healthy controls. RESULTS: Mild COVID-19 survivors had significantly lower Valsalva ratio (1.578 ± 0.2747 vs 1.773 ± 0.3459; p = .0156) and displayed a greater fall in systolic blood pressure during head-up tilt test (-9.206 ± 7.121 vs 1.147 ± 8.457; p < .0001) in comparison to the healthy controls. Haemodynamic cardiovascular autonomic abnormalities were seen in 47% of COVID-19 survivors. Haemodynamic criteria of orthostatic hypotension were met in 12% of COVID-19 survivors, and postural orthostatic tachycardia syndrome haemodynamic criteria were met in 35% of COVID-19 survivors. Autonomic reflex responses to deep breathing, handgrip test and cold pressor test were found to be comparable between the two groups. CONCLUSION: Young adult mild COVID-19 survivors show lower cardiovagal and cardiovascular adrenergic responses to baroreflex-dependent autonomic reactivity as medium- to long-term autonomic sequelae. They have an intact non-baroreflex-dependent autonomic reactivity.