Association Between Supine Hypertension And Autonomic Impairment In Patients With Autonomic Failure

Autonomic failure is characterized by an inability to regulate blood pressure (BP). The dominant clinical manifestation of these patients is orthostatic hypotension (OH). However, at least half of them also have supine hypertension, which can arise de novo or due to worsening of preexisting essential hypertension. We hypothesized that, regardless of the cause of hypertension, the loss of baroreflex buffering capacity in these patients contributes to the severity of their hypertension. Thus, we tested whether supine hypertension reflects the severity of autonomic impairment (i.e., reduced BP buffering capacity) in a retrospective cohort of 307 patients (66±1 yr, 183 males, BMI 26.1±0.3) with a diagnosis of neurogenic OH due to multiple system atrophy (MSA, n=95) or peripheral autonomic failure (pAF, n=212). Autonomic impairment was assessed by standard autonomic testing (posture test, Valsalva maneuver [VM], and sinus arrhythmia [SA] ratio) performed off pressor and antihypertensive medications. The association between supine systolic BP (SBP; median [interquartile range, IQR], 146 [130-168] mmHg) and autonomic testing was assessed using multiple regression analyses. After adjusting for age, sex, BMI, and type of autonomic failure (MSA vs. pAF), we found that supine SBP was positively related to age (β=0.33; P=0.034), the severity of OH (the drop in SBP on standing; β= -0.48, P<0.001), and indices of severity of autonomic impairment, including the lack of adequate compensatory increase in heart rate in the setting of OH (ΔHR/ΔSBP, β=-15.43, P=0.044), and lack of recovery of SBP during late phase 2 of the Valsalva maneuver (β=-0.31; P<0.001; model R 2 =0.55, P<0.001). VM and SA ratios were not related to supine hypertension. In conclusion, we postulate that the magnitude of supine hypertension correlates with the severity of autonomic impairment and that both OH and supine hypertension reflect the inability of autonomic failure to regulate blood pressure.