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.

Conclusion: 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.

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.