Combination of cardiorespiratory reflex parameters and heart rate variability power spectrum analysis for early diagnosis of diabetic cardiac autonomic neuropathy

Aim. - The study objective was to compare cardiorespiratory reflex (CR-R) parameters and heart rate variability power spectrum (HRV-PS) analysis in the diagnosis of cardiac autonomic neuropathy (CAN) in diabetic patients. Methods. - Four CR-R tests (Valsalva manoeuvre, deep breathing, and two successive 5-minute periods with the subject supine and standing, respectively) were performed in 399 diabetic patients (58.6% male, median age: 51 years) and 105 healthy controls (40% male, median age: 34 years). Patients with two or more abnormal CR-R parameters were classified as CAN+, while those with only one abnormal CR-R parameter were considered CAN 'borderline'. HRV-PS was performed in all study participants. Results. - The low-frequency (LF) area with the patient standing was reduced in CAN+ diabetics (median 35.6 normalized units [nu], n = 31), in CAN 'borderline' diabetics (median 64.3 nu, n = 70) and even in diabetics without CAN (median 89.4 nu, n = 298) versus control subjects (median 93.7 nu; P < 0.001, P < 0.001 and P < 0.05, respectively). Adding the abnormal (< 2.5 nu) LF area to the diagnostic criteria in CAN 'borderline' patients Caused 11 (15.7%) patients to be considered CAN+. Conclusion. - Combining abnormal CR-R parameters (I - E and I/E the most specific) with HRV-PS (particularly the LF area with the subject standing) allowed diagnosis of diabetic CAN at an earlier stage. (C) 2009 Elsevier Masson SAS. All rights reserved.