title: Heart rate variability risk score for prediction of acute cardiac complications in ED patients with chest pain.
abstract: BACKGROUND
  We aimed to develop a risk score incorporating heart rate variability (HRV) and traditional vital signs for the prediction of early mortality and complications in patients during the initial presentation to the emergency department (ED) with chest pain.
  
  
  METHODS
  We conducted a prospective observational study of patients with a primary complaint of chest pain at the ED of a tertiary hospital. The primary outcome was a composite of mortality, cardiac arrest, ventricular tachycardia, hypotension requiring inotropes or intraaortic balloon pump insertion, intubation or mechanical ventilation, complete heart block, bradycardia requiring pacing, and recurrent ischemia requiring revascularization, all within 72 hours of arrival at ED.
  
  
  RESULTS
  Three hundred nine patients were recruited, and 25 patients met the primary outcome. Backwards stepwise logistic regression was used to derive a scoring model that included heart rate, systolic blood pressure, respiratory rate, and low frequency to high frequency ratio. For predicting complications within 72 hours, the risk score performed with an area under the curve of 0.835 (95% confidence interval [CI], 0.749-0.920); and a cutoff of 4 and higher in the risk score gave a sensitivity of 0.880 (95% CI, 0.677-0.968), specificity of 0.680 (95% CI, 0.621-0.733), positive predictive value of 0.195, and negative predictive value of 0.985. The risk score performed better than ST elevation/depression and troponin T in predicting complications within 72 hours.
  
  
  CONCLUSIONS
  A risk score incorporating heart rate variability and vital signs performed well in predicting mortality and other complications within 72 hours after arrival at ED in patients with chest pain.
authors.affiliation: Department of Emergency Medicine, Singapore General Hospital, Outram Road, Singapore 169608. Marcus.ong.e.h@sgh.com.sg
authors.forename: Marcus Eng Hock
authors.initials: ME
authors.lastname: Ong
authors.forename: Ken
authors.initials: K
authors.lastname: Goh
authors.forename: Stephanie
authors.initials: S
authors.lastname: Fook-Chong
authors.forename: Benjamin
authors.initials: B
authors.lastname: Haaland
authors.forename: Khin Lay
authors.initials: KL
authors.lastname: Wai
authors.forename: Zhi Xiong
authors.initials: ZX
authors.lastname: Koh
authors.forename: Nur
authors.initials: N
authors.lastname: Shahidah
authors.forename: Zhiping
authors.initials: Z
authors.lastname: Lin
mesh_terms: D000368:Aged; D019540:Area Under Curve; D001919:Bradycardia / Q000175:diagnosis / Q000401:mortality / Q000503:physiopathology; D002637:Chest Pain / Q000175:diagnosis* / Q000209:etiology / Q000401:mortality / Q000503:physiopathology; D004636:Emergency Service, Hospital; D005260:Female; D006323:Heart Arrest / Q000175:diagnosis / Q000401:mortality / Q000503:physiopathology; D006327:Heart Block / Q000175:diagnosis / Q000401:mortality / Q000503:physiopathology; D006331:Heart Diseases / Q000175:diagnosis* / Q000401:mortality / Q000503:physiopathology; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011446:Prospective Studies; D012307:Risk Factors; D012680:Sensitivity and Specificity; D017180:Tachycardia, Ventricular / Q000175:diagnosis / Q000401:mortality / Q000503:physiopathology
keywords: ACS; AF; AMI; AUC; CABG; CI; ECG; ED; HFP; HRV; IRB; Institutional Review Board; LFP; PACS; PCI; Patient Acuity Category Scale; ROC; SBP; SGH; Singapore General Hospital; VLFP; VT; acute coronary syndrome; acute myocardial infarction; area under the receiver operating characteristic curve; atrial fibrillation; confidence interval; coronary artery bypass surgery; electrocardiography; emergency department; heart rate variability; high-frequency power; low-frequency power; percutaneous coronary intervention; receiver operating characteristic; systolic blood pressure; ventricular tachycardia; very low frequency power