Baseline characteristics of the study population
| Cardiac origin (n=1197) | Pulmonary origin (n=1908) | Total (n=3105) | P value | |
| Clinical characteristics | ||||
| Age, years | 73±14 | 65±17 | 68±16 | <0.001 |
| Female sex, n (%) | 537 (44.9) | 763 (40.0) | 1300 (41.9) | 0.008 |
| BMI (kg/m2) | 24.2±4.7 | 22.9±4.1 | 23.4±4.4 | <0.001 |
| History of HF, n (%) | 291 (24.3) | 85 (4.5) | 376 (12.1) | <0.001 |
| DM, n (%) | 338 (28.3) | 258 (13.5) | 596 (19.2) | <0.001 |
| HTN, n (%) | 435 (36.4) | 327 (17.1) | 762 (24.5) | <0.001 |
| CKD, n (%) | 257 (21.5) | 54 (2.8) | 311 (10.0) | <0.001 |
| CAD, n (%) | 235 (19.6) | 117 (6.1) | 352 (11.3) | <0.001 |
| MI, n (%) | 75 (6.3) | 42 (2.2) | 117 (3.8) | <0.001 |
| COPD, n (%) | 57 (4.8) | 196 (10.3) | 253 (8.1) | <0.001 |
| AF, n (%) | 458 (38.3) | 92 (4.8) | 550 (17.7) | <0.001 |
| Laboratory findings | ||||
| LVEF (%) | 45.5±14.7 | 56.7±12.2 | 48.8±14.9 | <0.001 |
| E/e’ | 17.3±7.5 | 15.6±6.7 | 16.9±7.4 | 0.001 |
| Laboratory findings | ||||
| BUN (mg/dL) | 24.6±15.8 | 19.6±14.7 | 21.6±15.3 | <0.001 |
| Creatinine (mg/dL) | 1.4±1.4 | 1.2±1.2 | 1.3±1.2 | <0.001 |
| eGFR (mL/min/1.73 m2) | 63.2±30.4 | 75.4±32.9 | 70.7±32.5 | <0.001 |
| NT-proBNP (pg/mL) | 3524.0 (1068.0–8191.0) | 445.0 (131.0–1767.0) | 1241.0 (247.0–4715.0) | <0.001 |
| Log-NT-proBNP (pg/mL) | 3.5 (3.0–3.9) | 2.6 (2.1–3.2) | 3.0 (2.3–3.7) | <0.001 |
| WBC (x109/L) | 8.6±3.7 | 10.9±5.8 | 9.9±5.2 | <0.001 |
| Neutrophil (%) | 67.1±13.2 | 76.3±12.7 | 72.8±13.6 | <0.001 |
| ESR (mm/hour) | 23.0±24.0 | 52.4±34.1 | 41.0±33.8 | <0.001 |
| CRP (mg/dL) | 1.8±3.0 | 10.8±9.8 | 7.5±9.1 | <0.001 |
| ECG findings | ||||
| Heart rate (beats/min) | 89.8±24.6 | 92.3±20.5 | 91.7±21.5 | 0.017 |
| PR interval (ms) | 167.8±34.5 | 155.6±26.1 | 157.8±28.1 | <0.001 |
| QRS duration (ms) | 99.6±22.9 | 90.7±15.6 | 92.8±18.0 | <0.001 |
| QT interval (ms) | 397.5±63.1 | 365.9±45.4 | 373.3±51.8 | <0.001 |
| Corrected QT interval (ms) | 472.5±43.7 | 445.7±38.9 | 452.0±41.6 | <0.001 |
| P axis | 48.2±29.3 | 51.6±24.2 | 51.0±25.2 | 0.021 |
| R axis | 30.0±56.9 | 40.6±44.5 | 38.1±47.9 | <0.001 |
| T axis | 79.1±81.5 | 47.1±42.0 | 54.5±55.5 | <0.001 |
| AI-ECG prediction probability | ||||
| Probability for pulmonary origin | 0.10 (0.01–0.46) | 0.91 (0.78–0.96) | 0.79 (0.17–0.94) | <0.001 |
| Pulmonary causes, n (%) | 284 (23.7) | 1681 (88.1) | 1965 (63.3) | <0.001 |
| Probability for cardiac origin | 0.90 (0.54–0.99) | 0.09 (0.04–0.22) | 0.21 (0.06–0.83) | <0.001 |
| Cardiac causes, n (%) | 913 (76.3) | 227 (11.9) | 1140 (36.7) | <0.001 |
Variables are expressed as the mean±SD, median (IQR), or n (%).
AF, atrial fibrillation; AI, artificial intelligence; BMI, body mass index; BUN, blood urea nitrogen; CAD, coronary artery disease; CKD, chronic kidney disease; COPD, chronic obstructive pulmonary disease; CRP, C reactive protein; DM, diabetes mellitus; e’, septal mitral annular velocity; E, early mitral inflow; eGFR, estimated glomerular filtration rate; ESR, erythrocyte sedimentation rate; HF, heart failure; HTN, hypertension; LVEF, left ventricular ejection fraction; MI, myocardial infarction; NT-proBNP, N-terminal probrain natriuretic peptide; WBC, white blood cell.