Combination of cardiorespiratory reflex parameters and heart rate variability power spectrum analysis for early diagnosis of diabetic cardiac autonomic neuropathy.Diabetes Metab. 2009 Sep; 35(4):305-11.DM
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.
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.
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 64.3nu, n=70) and even in diabetics without CAN (median 89.4nu, n=298) versus control subjects (median 93.7nu; 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+.
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.