A blunted heart rate increase during hypotension suggests a neurogenic cause, with a ΔHR/ΔSBP ratio < 0.5 bpm/mmHg being diagnostic of neurogenic orthostatic hypotension (AUC 0.96, p < 0.0001).
Observational (n=402)
Yes
Does the ΔHR/ΔSBP ratio distinguish neurogenic from nonneurogenic orthostatic hypotension in patients with normal sinus rhythm?
A ΔHR/ΔSBP ratio < 0.5 bpm/mmHg is highly sensitive and specific for diagnosing a neurogenic cause of orthostatic hypotension.
Absolute Event Rate: 8% vs 25%
p-value: p=<0.0001
OBJECTIVE: Blunted tachycardia during hypotension is a characteristic feature of patients with autonomic failure, but the range has not been defined. This study reports the range of orthostatic heart rate (HR) changes in patients with autonomic failure caused by neurodegenerative synucleinopathies. METHODS: Patients evaluated at sites of the U.S. Autonomic Consortium (NCT01799915) underwent standardized autonomic function tests and full neurological evaluation. RESULTS: We identified 402 patients with orthostatic hypotension (OH) who had normal sinus rhythm. Of these, 378 had impaired sympathetic activation (ie, neurogenic OH) and based on their neurological examination were diagnosed with Parkinson disease, dementia with Lewy bodies, pure autonomic failure, or multiple system atrophy. The remaining 24 patients had preserved sympathetic activation and their OH was classified as nonneurogenic, due to volume depletion, anemia, or polypharmacy. Patients with neurogenic OH had twice the fall in systolic blood pressure (SBP; -44 ± 25 vs -21 ± 14 mmHg mean ± standard deviation, p < 0.0001) but only one-third of the increase in HR of those with nonneurogenic OH (8 ± 8 vs 25 ± 11 beats per minute bpm, p < 0.0001). A ΔHR/ΔSBP ratio of 0.492 bpm/mmHg had excellent sensitivity (91.3%) and specificity (88.4%) to distinguish between patients with neurogenic from nonneurogenic OH (area under the curve = 0.96, p < 0.0001). Within patients with neurogenic OH, HR increased more in those with multiple system atrophy (p = 0.0003), but there was considerable overlap with patients with Lewy body disorders. INTERPRETATION: A blunted HR increase during hypotension suggests a neurogenic cause. A ΔHR/ΔSBP ratio < 0.5 bpm/mmHg is diagnostic of neurogenic OH. Ann Neurol 2018;83:522-531.
Norcliffe‐Kaufmann et al. (2018) conducted an observational in Orthostatic hypotension (n=402). Neurogenic orthostatic hypotension vs. Nonneurogenic orthostatic hypotension was evaluated on Increase in heart rate during orthostatic hypotension (bpm) (p=<0.0001). A blunted heart rate increase during hypotension suggests a neurogenic cause, with a ΔHR/ΔSBP ratio < 0.5 bpm/mmHg being diagnostic of neurogenic orthostatic hypotension (AUC 0.96, p < 0.0001).