Table 1.
Baseline Patient Characteristics by ICD Indication
| Primary Prevention | Secondary Prevention | P Value | |
|---|---|---|---|
| N=5091 | N=1929 | ||
| Demographics | |||
| Male, n (%) | 4037 (79.3) | 1560 (80.9) | 0.143 |
| Age at ICD implant date, n (%) | 64.51±11.93 | 65.47±12.58 | 0.003 |
| Cardiomyopathy details | |||
| Ischemic, n (%) | 4738 (93.1) | 1712 (88.8) | <0.001 |
| Ischemic+previous revascularization, n (%) | 3320 (65.2) | 1377 (71.4) | … |
| Previous heart failure, n (%) | 1886 (37.0) | 439 (22.8) | <0.001 |
| Device details | |||
| Cardiac resynchronization‐defibrillator, n (%) | 1678 (33.0) | 178 (9.2) | <0.001 |
| Dual‐chamber ICD, n (%) | 1311 (25.8) | 831 (43.1) | … |
| Single‐chamber ICD, n (%) | 2100 (41.2) | 918 (47.6) | … |
| Medical comorbidities | |||
| Atrial fibrillation, n (%) | 1506 (29.6) | 609 (31.6) | 0.105 |
| Diabetes mellitus, n (%) | 1571 (30.9) | 472 (24.5) | <0.001 |
| Current cigarette smoking, n (%) | 751 (14.8) | 325 (16.8) | 0.03 |
| Hypertension, n (%) | 2900 (57.0) | 1209 (62.7) | <0.001 |
| Stroke or transient ischemic attack, n (%) | 184 (3.6) | 87 (4.5) | 0.082 |
| Peripheral vascular disease, n (%) | 514 (10.1) | 219 (11.4) | 0.124 |
| COPD, n (%) | 636 (12.5) | 219 (11.4) | 0.192 |
| Clinical variables | |||
| Reported NYHA class | |||
| III or IV | 1778 (34.9%) | 283 (14.7%) | … |
| Systolic blood pressure, mean±SD | 121.46±19.91 | 124.62±20.08 | <0.001 |
| Mean QRS duration, mean±SD | 132.93±35.62 | 122.47±33.18 | <0.001 |
| Testing | |||
| Serum creatinine, median (IQR) | 96.00 (80.00–120.00) | 95.00 (80.00–117.00) | 0.092 |
| Hb <110 g/L, n (%) | 385 (7.6) | 422 (21.9) | <0.001 |
| LVEF | |||
| LVEF ≤20, n (%) | 1033 (20.3) | 201 (10.4) | <0.001 |
| LVEF: 21 to 30, n (%) | 2695 (52.9) | 471 (24.4) | <0.001 |
| LVEF: >30, n (%) | 1208 (23.7) | 1079 (55.9) | <0.001 |
| Medications | |||
| β‐Adrenoreceptor antagonist, n (%) | 4388 (86.2) | 1616 (83.8) | 0.01 |
| ACEI, n (%) | 3614 (71.0) | 1273 (66.0) | <0.001 |
| ARB, n (%) | 904 (17.8) | 253 (13.1) | <0.001 |
| Spironolactone, n (%) | 1556 (30.6) | 287 (14.9) | <0.001 |
| Loop diuretics, n (%) | 3144 (61.8) | 753 (39.0) | <0.001 |
| Digoxin, n (%) | 1202 (23.6) | 238 (12.3) | <0.001 |
| Amiodarone, n (%) | 499 (9.8) | 696 (36.1) | <0.001 |
| Statin, n (%) | 3632 (71.3) | 1386 (71.9) | 0.673 |
| Aspirin, n (%) | 3012 (59.2) | 1376 (71.3) | <0.001 |
| Clopidogrel, n (%) | 915 (18.0) | 586 (30.4) | <0.001 |
Baseline characteristics of subjects. Patients with ICDs for primary prevention had lower LVEF, had more previous history of heart failure, higher prevalence of ICM and diabetes mellitus, and were more likely to have a cardiac resynchronization therapy defibrillator than the secondary prevention group and more frequently on heart failure medications. ACEI indicates angiotensin‐converting enzyme inhibitor; ARB, angiotensin receptor blocker; COPD, chronic obstructive pulmonary disease; Hb, hemoglobin; ICD, implantable cardioverter defibrillator; IQR, interquartile range; LVEF, left ventricular ejection fraction; NICM, nonischemic cardiomyopathy; NYHA, New York Heart Association.