Table 1.
Comparison of Demographic, Anatomic, Surgical, CMR, and Arrhythmia Characteristics Stratified by Study Cohort
| Variable | All patients (N=1552) | Development (n=1221) | Validation (n=331) | P value |
|---|---|---|---|---|
| Demographics | ||||
| Age at repair, y | 2.12 (0.44–6.01) [IQR] | 1.16 (0.32–4.94) [IQR] | 5.22 (3.82–8.48) [IQR] | <0.001 |
| Year of TOF repair ≤1985, n (%) | 734 (47.3) | 497 (40.7) | 237 (71.6) | <0.001 |
| Age at CMR, y | 23.4 (15.6–35.6) [IQR] | 20.7 (13.9–33.0) [IQR] | 31.1 (23.0–40.8) [IQR] | <0.001 |
| Time from repair to CMR, y | 20.2 (13.9–29.4) [IQR] | 18.6 (12.9–28.2) [IQR] | 24.6 (18.7–32.3) [IQR] | <0.001 |
| Follow‐up time after CMR, y | 9.5 (4.1–14.6) [IQR] | 8.2 (3.4–13.4) [IQR] | 13.9 (10.1–15.8) [IQR] | <0.001 |
| Sex, male, n (%) | 853 (55.0) | 660 (54.1) | 193 (58.3) | 0.17 |
| BMI at CMR, kg/m2 | 24.0±5.9 | 23.7±6.2 | 25.3±4.9 | <0.001 |
| Diagnosis | ||||
| TOF diagnosis, n (%) | <0.001 | |||
| TOF/PS | 1296 (83.5) [IQR] | 984 (80.6) [IQR] | 312 (94.3) [IQR] | |
| TOF/PA | 256 (16.5) [IQR] | 237 (19.4) [IQR] | 19 (5.7) [IQR] | |
| Genetic anomaly, n (%) | 192 (12.4) | 159 (13.0) | 33 (10.0) | 0.16 |
| Additional cardiovascular anomaly | 717 (46.2) [IQR] | 540 (44.2) [IQR] | 177 (53.5) [IQR] | <0.01 |
| MAPCAs, n (%) | 58 (3.7) | 53 (4.3) | 5 (1.5) | 0.02 |
| Absent pulmonary valve | 28 (1.8) [IQR] | 22 (1.8) [IQR] | 6 (1.8) [IQR] | 0.99 |
| Prior procedures | ||||
| Pre‐TOF repair palliative shunt, n (%) | 488 (31.4) | 330 (27.0) | 158 (47.7) | <0.001 |
| TOF repair type, n (%) | <0.001 | |||
| Transannular patch | 773 (49.8) [IQR] | 643 (52.7) [IQR] | 130 (39.3) [IQR] | |
| Right ventricle‐to‐pulmonary artery conduit | 221 (14.2) [IQR] | 198 (16.2) [IQR] | 23 (6.9) [IQR] | |
| Other | 558 (36.0) [IQR] | 380 (31.1) [IQR] | 178 (53.8) [IQR] | |
| Postrepair cardiac procedures | 935 (60.2) [IQR] | 712 (58.3) [IQR] | 223 (67.4) [IQR] | <0.01 |
| Postrepair PVR | 893 (57.5) [IQR] | 716 (58.6) [IQR] | 177 (53.5) [IQR] | 0.10 |
| CMR measurement | ||||
| RVEDVi, mL/m2 | 146.1±46.4 | 145.4±46.6 | 148.6±45.6 | 0.27 |
| RVESVi, mL/m2 | 76.2±33.8 | 74.6±34.1 | 81.8±32.3 | <0.001 |
| RVEF, % | 49.1±8.8 | 49.9±8.6 | 45.9±8.6 | <0.001 |
| RV mass index, g/m2 | 32.2±11.5 | 33.3±12.1 | 28.3±8.1 | <0.001 |
| RV mass/volume ratio, g/mL | 0.23±0.07 | 0.24±0.08 | 0.20±0.04 | <0.001 |
| LVEDVi, mL/m2 | 86.9±20.9 | 86.7±20.0 | 87.8±23.7 | 0.42 |
| LVESVi, mL/m2 | 37.6±14.8 | 37.2±13.5 | 39.0±18.7 | 0.11 |
| LVEF, % | 57.5±7.8 | 57.7±7.1 | 56.7±9.9 | 0.07 |
| LV mass index, g/m2 | 51.7±14.3 | 52.4±14.6 | 49.0±13.2 | <0.001 |
| LV mass/volume ratio, g/mL | 0.61±0.15 | 0.62±0.16 | 0.57±0.12 | <0.001 |
| BVGFI | 48.2±8.5 | 48.5±8.3 | 47.2±9.1 | 0.02 |
| RV/LVEDV ratio | 1.73±0.55 | 1.72±0.55 | 1.75±0.57 | 0.42 |
| Rhythm data | ||||
| Atrial arrhythmia, n (%) | 190 (12.2) | 135 (11.1) | 55 (16.6) | <0.01 |
| Nonsustained VT, n (%) | 255 (16.4) | 213 (17.4) | 42 (12.7) | 0.04 |
| Pacemaker, n (%) | 30 (1.9) | 22 (1.8) | 8 (2.4) | 0.50 |
| Implantable cardioverter‐defibrillator, n (%) | 109 (7.0) | 92 (7.5) | 17 (5.1) | 0.15 |
| QRS duration, ms | 144.9±27.2 | 142.6±27.0 | 153.2±26.1 | <0.001 |
| Outcomes | ||||
| All‐cause death, n (%) | 102 (6.6) | 74 (6.1) | 28 (8.5) | 0.13 |
| Cause of death, n (%) | 0.69 | |||
| Cardiac | 47 (46.1) [IQR] | 35 (47.3) [IQR] | 12 (42.9) [IQR] | |
| Noncardiac | 26 (25.5) [IQR] | 17 (23.0) [IQR] | 9 (32.1) [IQR] | |
| Unknown | 29 (28.4) [IQR] | 22 (29.7) [IQR] | 7 (25.0) [IQR] | |
| Nonsustained VT, n (%) | 186 (12.0) | 155 (12.7) | 31 (9.4) | 0.11 |
| Sustained VT, n (%) | 31 (2.0) | 24 (2.0) | 7 (2.1) | 0.83 |
| Aborted sudden death, n (%) | 15 (1.0) | 15 (1.2) | 0 (0) | 0.05 |
| Atrial arrhythmia, n (%) | 126 (8.1) | 91 (7.5) | 35 (10.6) | 0.07 |
BMI indicates body mass index; BVGFI, biventricular global function index; CMR, cardiovascular magnetic resonance imaging; ICD, implantable cardioverter‐defibrillator; LV, left ventricular; LVEDV, left ventricular end‐diastolic volume; LVEDVi, left ventricular end‐diastolic volume index; LVEF, left ventricular ejection fraction; LVESVi, left ventricular end‐systolic volume index; MAPCAs, major aortopulmonary collateral arteries; PA, pulmonary atresia; PS, pulmonary stenosis; PVR, pulmonary valve replacement; RV, right ventricular; RVEDVi, right ventricular end‐diastolic volume index; RVEF, right ventricular ejection fraction; RVESVi, right ventricular end‐systolic volume index; TOF, tetralogy of Fallot; and VT, ventricular tachycardia.