Key result
Patients with neurally mediated syncope had a greater decrease in systolic blood pressure (-14.7 vs -7.6 mm Hg, P<0.01) and baroreflex sensitivity during orthostatic stress compared to controls.
Why the study?
Do hemodynamic parameters and baroreflex sensitivity differ during orthostatic stress in patients with neurally mediated syncope compared to controls?
Case-Control (n=132)
Do hemodynamic parameters and baroreflex sensitivity differ during orthostatic stress in patients with neurally mediated syncope compared to controls?
Absolute Event Rate: -14.7% vs -7.6%
p-value: p=<0.01
Dysfunctional baroreflex sensitivity in response to orthostatic stress may contribute to the pathological autonomic cardiac modulation seen in neurally mediated syncope.
Greater BP drop during tilt with higher pretest BRS in NMS supports baroreflex evaluation; leaves open diagnostic or therapeutic utility.
Background We aimed to investigate differences in hemodynamic parameters and the role of baroreflex sensitivity (BRS) in patients with a history of neurally mediated syncope (NMS) compared with a control group. Methods Hemodynamic parameters and BRS were continuously measured noninvasively using a Finometer at rest and during passive head‐up tilt test (HUT) in patients with a history of NMS (n = 55) and a control group (n = 77). The tilting period was divided into pretest (resting supine position), initial (first 3 minutes of tilting), last (last 3 minutes of tilting), and recovery (3 minutes after tilting was complete) periods. Results Decrease in systolic blood pressure (− 14.7 ± 15.7 mm Hg vs − 7.6 ± 14.3 mm Hg, P < 0.01) was more prominent and increase in total systemic peripheral resistance was significantly smaller (67.6 ± 418.7 dyn.s/cm 5 vs 189.4 ± 261.0 dyn.s/cm 5 , P = 0.04) from the initial to the last period of HUT in the patient group compared with the control group. BRS was significantly higher during the pretest period (20.1 ± 10.9 ms/mm Hg vs 13.0 ± 8.1 ms/mm Hg, P < 0.01) in the patient group, while the decrease in BRS from the pretest to the initial period was greater (−8.5 ± 6.0 ms/mm Hg vs − 3.2 ± 4.1 ms/mm Hg, P = 0.01). Conclusions Dysfunctional BRS in response to orthostatic stress might be involved in pathological autonomic cardiac modulation of NMS.
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Lee et al. (2017) conducted a case-control in Neurally mediated syncope (n=132). History of neurally mediated syncope vs. Control group was evaluated on Decrease in systolic blood pressure from the initial to the last period of head-up tilt test (p=<0.01). Patients with neurally mediated syncope had a greater decrease in systolic blood pressure (-14.7 vs -7.6 mm Hg, P<0.01) and baroreflex sensitivity during orthostatic stress compared to controls.
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