Background: The clinical presentation of Parkinson's disease (PD) includes a wide spectrum of non-motor features, including cardiovascular autonomic failure.
Objective: To evaluate cardiovascular autonomic status and cardiac functional capacity in drug-naïve PD patients.
Methods: 18 newly-diagnosed PD patients underwent laboratory cardiovascular autonomic function tests using power spectral analysis of the R-R interval, blood pressure (BP) short-term variability and non-invasive baroreflex sensitivity (BRS). A two-dimensional (2D) transthoracic echocardiogram, spirometry and cardiopulmonary exercise test (CPET) were also performed. Thirteen patients underwent myocardial scintigraphy with [123I] metaiodobenzylguanidine (MIBG).
Results: At rest, total power spectral analysis of heart rate variability was lower in PD patients than in controls. BRS decreased during sympathetic activation in both patients and controls. While echocardiography and spirometry were normal, a mild degree of exercise intolerance was observed at the CPET in PD patients (mean V'O2max: 83% of predicted; mean Wmax: 80% of predicted). The heart-to-mediastinum (H/M) ratio of MIBG uptake was pathologically impaired in 9 patients, one of whom displayed a definite cardiovascular dysautonomic pattern.
Conclusions: Our results confirm that subclinical to overt cardiovascular autonomic failure may occur from the early stages of PD. The less efficient adaptive response to physical stimuli during the CPET and postural changes observed in untreated PD patients possibly reflect cardiac sympathetic denervation, although the involvement of PD-related motor impairment in physical deconditioning cannot be excluded.
Keywords: Cardiopulmonary exercise test; Cardiovascular autonomic failure; Non-motor symptoms; Orthostatic hypotension; Parkinson's disease.
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