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Response of Neurocardiac Syncope to β‐Blocker Therapy: Interaction Between Age and Parasympathetic Tone
Author(s) -
SLOTWINER DAVID J.,
STEIN KENNETH M.,
LIPPMAN NEAL,
MARKOWITZ STEVEN M.,
LERMAN BRUCE B.
Publication year - 1997
Publication title -
pacing and clinical electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.686
H-Index - 101
eISSN - 1540-8159
pISSN - 0147-8389
DOI - 10.1111/j.1540-8159.1997.tb03909.x
Subject(s) - medicine , supine position , atenolol , orthostatic vital signs , cardiology , tilt table test , blockade , beta blocker , anesthesia , heart rate , blood pressure , heart failure , receptor
Beta‐blockers are a first line therapy for neurocardiac syncope, but are not always effective. The purpose of this study was to determine whether differential autonomic responses to orthostasis predict the response of patients with neurocardiac syncope to β‐adrenergic blockade. We computed the RMS successive difference of the BB intervals (BMSSD: a measure of cardiac parasympathetic tone) during supine and upright phases of the initial tilt test in 28 patients with syncope and positive tilt tests who were treated with atenolol. Follow‐up tilt testing was performed to assess the efficacy of the drug in preventing tilt induced neurocardiac syncope. BMSSD did not differ at baseline (supine) between those who did (n = 20) and did not (n = 8) respond to β‐blockade. However, withdrawal of parasympathetic tone in response to tilt varied inversely with age (r =−0.69; P < 0.01). Reduced age adjusted parasympathetic withdrawal during orthostasis was associated with a 47% versus 8% risk of β‐blockade failure (odds ratio = 11; P = 0.01). Patients with diminished age adjusted parasympathetic withdrawal during orthostatic stress are less likely to respond to β‐blocker therapy of neurocardiac syncope than their counterparts. This may reflect a correspondingly greater sympathetic response to orthostasis in these patients, but the mechanism for this interaction is undetermined.