Figure 2: ROC curve analysis of the studied parameters. (a) ROC curve of HRR for prediction of hospital readmission/death. (b) ROC curve of resting HR for prediction of hospital readmission/death. (c) ROC curve of CR for prediction of hospital readmission/death. ROC: Receiver operator characteristic, HRR: Heart rate recovery, HR: Heart rate, CR: Chronotropic reserve.