Decreased heart rate variability predicts death in amyotrophic lateral sclerosis

Some patients with amyotrophic lateral sclerosis (ALS) die suddenly despite normal nocturnal pulse oximetry (NPO), possibly due to dysautonomia.

Forty-four ALS patients without other medical conditions were studied. Heart rate variability was assessed through finger oximetry. The heart rate coefficient of variation (HR CV) was evaluated during nocturnal sleep. All patients were investigated at study entry (T1); 13 were tested 4 months later (T2), and 21 patients were investigated a further 24 months after entry (T3). Only recordings obtained from patients with normal NPO were accepted.

HR maximal, minimum, and median values remained stable. HR CV was similar between T1 and T2, but it decreased significantly at T3 (P < 0.01). Very low values were observed in 4 patients at T3 (HR CV <0.20), and 3 died suddenly within the following 2 months, despite normal NPO.

Low HR CV is a potential marker of prognosis in ALS.