Chronotropic Incompetence During Exercise Testing as a Marker of Autonomic Dysfunction in Individuals with Early Parkinson’s Disease

Background: An attenuated heart rate response to exercise, termed chronotropic incompetence, has been reported in Parkinson’s disease (PD). Chronotropic incompetence may be a marker of autonomic dysfunction and a cause of exercise intolerance in early stages of PD. Objective: To investigate the relationship between chronotropic incompetence, orthostatic blood pressure change (supine – standing), and exercise performance (maximal oxygen consumption, VO2peak) in individuals with early PD within 5 years of diagnosis not on dopaminergic medications. Methods: We performed secondary analyses of heart rate and blood pressure data from the Study in Parkinson’s Disease of Exercise (SPARX). Results: 128 individuals were enrolled into SPARX (63.7±9.3 years; 57.0% male, 0.4 years since diagnosis [median]). 103 individuals were not taking chronotropic medications, of which 90 had a normal maximal heart rate response to exercise testing (155.3±14.0 bpm; PDnon-chrono) and 13 showed evidence of chronotropic incompetence (121.3±11.3 bpm; PDchrono, p