Spontaneous baroreflex sensitivity and heart rate variability are not superior to classic autonomic testing in older patients with type 2 diabetes

Background: Early detection of cardiac autonomic neuropathy (CAN) permits i ndividual risk stratification. Spontaneous heart rate variability (HRV) and baroreflex sensitivity (BRS) are suggested to be superior to classic auton omic testing in that they detect CAN earlier, with greater reliability, and do not require the patient's undue attention. Methods: To test that hypoth esis, we studied 53 diabetic patients (mean age, 55 years) and 38 age-match ed healthy control subjects (HC). Subjects underwent deep breathing, Valsal va maneuver, and orthostatic testing. Each abnormal test was counted as 1 p oint. A change in systolic blood pressure during standing of more than 10 m m Hg was graded with a single point; a decrease of more than 20 mm Hg recei ved 2 points. A total score of zero was regarded as no CAN (noCAN), a score greater than or equal to4 as severe CAN (sCAN), and scores of 1 to 3 as mi ld CAN (mCAN). Spontaneous BRS was determined using the sequence technique. HRV was calculated as coefficient of variation (CV), high Frequency power (HF) and low frequency power (LF). Results: Mean group values for HRV and B RS were: CV = 3.9 +/- 1.3; 4.0 +/- 1.3; 2.4 +/- 1.1; and 1.2 +/- 0.4; BRS = 8 +/- 3; 8 +/- 5; 5 +/- 2; and 2 +/- 2 msec/mm Hg for HC n = 38, noCAN n = 15, mCAN n = 26, and sCAN n = 12, respectively. BRS was similar in HC and patients with noCAN. In sCAN, BRS detected only 10 of 12 patients. HRV and BRS did not improve reclassification based on discriminant analysis. Conclu sion: BRS and HRV did not detect CAN in older diabetic patients better than classic autonomic testing.