By contrast, orthostatic HR increase by itself was a poor discriminator, according to the researchers, who reported that an HR increase of less than 17 bpm had just moderate sensitivity (79%) and specificity (87%).
“Using this simple bedside test of how much the blood pressure falls and heart rate increases can help in screening these patients,” Dr. Norcliffe-Kaufmann said of the results. “Then they can be sent to an autonomic clinic to really confirm the diagnosis with a sophisticated autonomic function test.”
The researchers also sought to determine whether the differences in heart rate could distinguish between central and peripheral causes of neurogenic orthostatic hypotension. They found that heart rate increased more in patients with multiple system atrophy, but noted “considerable overlap” with patients with Lewy body disorders, according to the findings.
“It didn’t really pan out as a way to distinguish the two forms from one another with enough sensitivity or specificity,” Dr. Norcliffe-Kaufmann said.