title: Heart rate variability: short-term studies are as useful as holter to differentiate diabetic patients from healthy subjects.
abstract: BACKGROUND
  The definitive incorporation of heart rate variability (HRV) as a clinical tool depends on the development of more confident techniques of measurement. The length of the studies is a critical issue. Whereas Holter studies allow the monitorization at different hours and activities, short-term recordings allow the control of environmental conditions. Recording length is also strongly related to the procedure of analysis; for instance, some time-domain indexes are strongly affected by the duration of the study. Meanwhile, spectral analyses require stationary conditions, only achieved in short-term studies. Our main goal was to determine if HRV indexes obtained from short-term analyses were as useful as those from Holter monitoring for diagnosis of reduced HRV in diabetes.
  
  
  METHODS
  We studied two groups: one with impaired HRV (15 diabetic patients) and another with normal HRV (15 healthy subjects). HRV indexes obtained from 24-hour Holter recordings (SDNN, rMSSD, and the power of LF and HF bands), were correlated with analog indexes obtained from 10-minute digital acquired studies within each group. Besides, we compared the diabetic and control groups using the indexes obtained with both methodologies.
  
  
  RESULTS
  The correlation was high (0.70<or=r <or= 0.85, P <or= 0.0032) in the diabetic group, but was poor in the control group. HRV values were significantly lower in the diabetic group either for 24-hour or short-term studies (P <or= 0.0113).
  
  
  CONCLUSIONS
  We conclude that short-term studies are at least as powerful as Holter to differentiate the diabetic group (impaired HRV) from the control group.
mesh_terms: D001145:Arrhythmias, Cardiac / Q000150:complications / Q000175:diagnosis*; D016022:Case-Control Studies; D003922:Diabetes Mellitus, Type 1 / Q000150:complications / Q000175:diagnosis*; D015716:Electrocardiography, Ambulatory; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology; D006339:Heart Rate; D006801:Humans; D008297:Male; D011336:Probability; D011379:Prognosis; D012016:Reference Values; D018570:Risk Assessment; D012494:Sampling Studies; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D013997:Time Factors