Baseline characteristics of index cases, that is, at the time of pacemaker implantation
| Index mother, n (%) | Index father, n (%) | Index sibling, n (%) | |
| Total | 9196 (100) | 16 050 (100) | 2853 (100) |
| Male sex | 0 (0) | 16 050 (100) | 1801 (63.1) |
| Median age | 76.2 (IQR 67.5–83.0) | 75.1 (IQR 67.6–81.6) | 51.4 (IQR 36.1–60.3) |
| Age at baseline, years | |||
| <30 | 126 | 80 | 539 |
| 30–40 | 130 | 180 | 299 |
| 40–50 | 286 | 399 | 497 |
| 50–60 | 695 | 1225 | 771 |
| 60–70 | 1596 | 3225 | 466 |
| 70–80 | 3032 | 5932 | 205 |
| 80–90 | 2821 | 4429 | 69 |
| >90 | 510 | 580 | 7 |
| Cardiovascular comorbidity | |||
| Congestive heart failure | 1084 (11.8) | 2469 (15.4) | 263 (9.2) |
| Diabetes mellitus | 1037 (11.3) | 2254 (14.0) | 211 (7.4) |
| Prior MI | 1380 (15.0) | 3650 (22.7) | 204 (7.2) |
| AF/AFL | 1387 (15.1) | 2899 (18.1) | 324 (11.4) |
| VT | 143 (1.6) | 297 (1.9) | 35 (1.2) |
AF, atrial fibrillation; AFL, atrial flutter ; MI, myocardial infarction; VT, ventricular tachycardia.