title: A simple bedside test of 1-minute heart rate variability during deep breathing as a prognostic index after myocardial infarction.
abstract: BACKGROUND
  We evaluate a simple, bedside test that measures 1-minute heart rate variability in deep breathing as a predictor of death after myocardial infarction.
  
  
  METHODS
  Bedside heart rate variability was assessed in 185 consecutive patients 5.1 +/- 2.5 days after a first myocardial infarction. Patients were instructed to take 6 deep respirations in 1 minute while changes in heart rate were measured and calculated by an electrocardiographic recorder. An abnormal test result was defined as a difference of less than 10 beats/min between the shortest and longest heart rate interval.
  
  
  RESULTS
  Heart rate variability <10 beats/min was found in 65 patients (35%) and was significantly lower (P <.05) in women, patients >60 years of age, patients with diabetes, patients with congestive heart failure, and patients taking angiotensin-converting enzyme inhibitors. Mean follow-up period was 16 months. Ten patients died during follow-up: 9 of cardiac causes and 1 of stroke. Nine of these 10 patients had heart rate variability <10 beats/min (P =.004). The sensitivity and specificity of this test for cardiovascular mortality is 90.0% and 68.0%, respectively. The negative predictive value is 99.2% and the relative risk is 16.6. Heart rate variability <10 beats/min remained a significant predictor of death after adjusting for clinical, demographic, and left ventricular function with an odds ratio of 1.38 (95% confidence interval, 1.13-1.63).
  
  
  CONCLUSIONS
  This simple, brief bedside deep breathing test of heart rate variability in patients after myocardial infarction appears to be a good predictor for all-cause mortality and sudden death. It may be used as a clinical test for risk stratification after myocardial infarction.
authors.affiliation: Cardiology Department, Soroka Medical Center, Beer-Sheva, Israel.
authors.forename: A
authors.initials: A
authors.lastname: Katz
authors.forename: I F
authors.initials: IF
authors.lastname: Liberty
authors.forename: A
authors.initials: A
authors.lastname: Porath
authors.forename: I
authors.initials: I
authors.lastname: Ovsyshcher
authors.forename: E N
authors.initials: EN
authors.lastname: Prystowsky
mesh_terms: D016757:Death, Sudden, Cardiac / Q000209:etiology*; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications / Q000401:mortality / Q000503:physiopathology*; D016017:Odds Ratio; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies; D012119:Respiration; D012306:Risk; D012680:Sensitivity and Specificity