| HP | heart period |
| RSA | respiratory sinus arrhythmia |
| CRC | cardiorespiratory coupling |
| CrossEn | cross-entropy |
| SSC | state space correspondence |
| KNN | k-nearest neighbor |
| HF | heart failure |
| SR | sinus rhythm |
| VA | ventricular arrhythmia |
| LVEF | left ventricular ejection fraction |
| CRT | cardiac resynchronization therapy |
| ECG | electrocardiogram |
| RESP | respiration |
| CP | cross-predictability |
| CPF | cross-predictability function |
| CPI | cross-predictability index |
| IS | information storage |
| PF | predictability function |
| PI | predictability index |