title: Parasympathetic dysfunction in hypertrophic cardiomyopathy assessed by heart rate variability: comparison between short-term and 24-h measurements.
abstract: In this study, we evaluate cardiac autonomic function in hypertrophic cardiomyopathy (HCM) by assessing heart rate variability (HRV), comparing a short-term laboratory method with an ambulatory (24-h) method, in patients with and without beta-blockade. Reduced HRV is a risk factor for adverse events in some cardiac diseases, but is not a proven risk indicator in HCM. Analysis of HRV has been based on either short- or long-term electrocardiographic recordings and previous studies in HCM have shown conflicting results. There is no consensus on which method to prefer, and we evaluate, for the first time, both short- and long-term analyses in patients with HCM. Long- and short-term HRV analyses were performed in 43 patients with HCM. They were divided in two groups, 22 patients on beta-blockade and 21 non-treated patients. As controls, 121 healthy subjects were used. Young patients without beta-blockade showed a reduction in HRV parameters reflecting parasympathetic function, both in the short- and long-term registrations, which was attenuated by beta-blockade. Parasympathetic autonomic regulation was found to be impaired in young patients with HCM. This may be of clinical relevance as abnormal autonomic function might be a substrate for malignant dysrhythmias. The impairment was attenuated by beta-blockade, which might indicate a clinically useful effect. We also show that short- and long-term methods yield similar results, suggesting that a short-term registration might be sufficient to assess HRV in patients with HCM.
authors.affiliation: Department of Medicine, University Hospital, Umeå, Sweden. stellan.morner@medicin.umu.se
authors.forename: Stellan
authors.initials: S
authors.lastname: Mörner
authors.forename: Urban
authors.initials: U
authors.lastname: Wiklund
authors.forename: Peter
authors.initials: P
authors.lastname: Rask
authors.forename: Bert-Ove
authors.initials: BO
authors.lastname: Olofsson
authors.forename: Elsadig
authors.initials: E
authors.lastname: Kazzam
authors.forename: Anders
authors.initials: A
authors.lastname: Waldenström
mesh_terms: D000328:Adult; D000368:Aged; D001145:Arrhythmias, Cardiac / Q000209:etiology / Q000503:physiopathology; D001342:Autonomic Nervous System Diseases / Q000150:complications / Q000503:physiopathology*; D002312:Cardiomyopathy, Hypertrophic / Q000000981:diagnostic imaging / Q000503:physiopathology*; D003430:Cross-Sectional Studies; D004452:Echocardiography; D005260:Female; D006321:Heart / Q000294:innervation / Q000502:physiology; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged