Comparison of heart rate variability and classic autonomic testing for detection of cardiac autonomic dysfunction in patients with fibromyalgia.

Aim Cardiac autonomic dysfunction (CAD) is frequently found in patients with fibromyalgia (FM). Thus, we evaluated whether heart rate variability (HRV) is superior to the Ewing tests in detecting CAD in FM patients. Methods We studied 35 females with FM and 25 age-matched healthy females. In Ewing tests, results were added to yield an overall score. An abnormal result on deep breathing, the Valsalva maneuver, or orthostatic standing was counted as 1 point. A change in systolic blood pressure (SBP) of > 10 mmHg while standing counted as 1 point, and a change of > 20 mmHg as 2 points. A score of 0 was regarded as no CAD, a score of ≥ 2 as severe CAD and a score of 1 as mild CAD. HRV was measured in two ways: by R-R intervals (time-domain analysis) and by spectral analysis of a series of successive R-R intervals (frequency-domain analysis). Results FM patients had significantly lower expiratory/inspiratory (E/I) ratios, lower Valsalva ratios and higher SBP values than healthy controls (P < 0.05, P < 0.05, P < 0.01, respectively). In the frequency domain, very low-frequency and low-frequency bands were also lower in FM patients than controls (both P < 0.05). Based on the discriminant analysis of the Ewing tests, 54.4% of cases were correctly classified. The addition of HRV parameters did not improve the reclassification. Conclusion HRV does not improve detection of CAD in FM patients over classic autonomic testing.