Table 1. Baseline Characteristics of Patients Who Underwent ICD Generator Change Stratified by EF.
| Clinical Characteristics* | Overall Cohort (n=253) |
EF≤35% (n=181) |
EF>35% (n=72) |
P Value |
|---|---|---|---|---|
| Age, y | 68.3 (12.7) | 68.2 (12.8) | 68.4 (12.6) | 0.77 |
| Male sex, n (%) | 207 (81.8) | 154 (85.1) | 53 (73.6) | 0.033 |
| White race | 231 (91.3) | 166 (91.7) | 65 (90.3) | 0.08 |
| Body mass index, kg/m2 | 28.7 (5.7) | 28.3 (5.5) | 29.5 (6.2) | 0.23 |
| Underlying cardiomyopathy, n (%) | ||||
| Ischemic cardiomyopathy | 194 (81.9) | 141 (83.4) | 55 (80.9) | 0.61 |
| Nonischemic cardiomyopathy | 41 (17.3) | 28 (16.6) | 13 (19.1) | |
| Reason for ICD generator change, n (%) | ||||
| Elective replacement indicator | 177 (70.0) | 124 (68.5) | 53 (73.6) | 0.67 |
| Device advisory or malfunction | 59 (23.3) | 43 (23.8) | 16 (22.2) | |
| Device upgrade | 10 (4.0) | 9 (5.0) | 1 (1.4) | |
| Infection | 6 (2.4) | 4 (2.2) | 2 (2.8) | |
| Lead revision at the time of ICD generator replacement, n (%) | 41 (16.2) | 33 (18.2) | 8 (11.1) | 0.17 |
| Left ventricular ejection fraction, n (%) | 32.3 (12.4) | 26.0 (6.4) | 47.7 (9.6) | <0.001 |
| NYHA class, n (%) | ||||
| Class I | 100 (50.3) | 65 (45.1) | 35 (63.6) | 0.043 |
| Class II | 70 (35.2) | 54 (37.5) | 16 (29.1) | |
| Class III | 29 (14.6) | 25 (17.4) | 4 (7.3) | |
| Rhythm, n (%) | ||||
| Sinus rhythm with intrinsic conduction | 134 (60.9) | 95 (62.1) | 39 (58.2) | 0.94 |
| Atrial fibrillation with intrinsic conduction | 12 (5.5) | 8 (5.2) | 4 (6.0) | |
| Ventricular paced rhythm | 60 (27.3) | 40 (26.1) | 20 (29.9) | |
| QRS duration, ms (median, interquartile range) | 118 (100–158) | 122 (104–156) | 113 (94–162) | 0.29 |
| Medications, n (%) | ||||
| ACE inhibitor/angiotensin receptor blocker | 197 (84.5) | 148 (89.2) | 49 (73.1) | 0.002 |
| β-Blocker | 217 (93.1) | 158 (95.2) | 59 (88.1) | 0.05 |
| Cardiovascular history, n (%) | ||||
| Myocardial infarction | 179 (70.8) | 128 (70.7) | 51 (70.8) | 0.99 |
| Coronary artery disease | 203 (80.2) | 150 (82.9) | 53 (73.6) | 0.10 |
| Atrial fibrillation | 115 (45.5) | 81 (44.8) | 34 (47.2) | 0.72 |
| Peripheral vascular disease | 40 (15.8) | 35 (19.3) | 5 (6.9) | 0.015 |
| Stroke/transient ischemic attack | 40 (15.8) | 32 (17.7) | 8 (11.1) | 0.20 |
| Medical comorbidities, n (%) | ||||
| Hypertension | 192 (75.9) | 134 (74.0) | 58 (80.6) | 0.27 |
| Diabetes mellitus | 88 (34.8) | 65 (35.9) | 23 (31.9) | 0.55 |
| Chronic lung disease | 33 (13.0) | 17 (9.4) | 16 (22.2) | 0.006 |
| Laboratory parameters | ||||
| Hemoglobin, g/dL | 12.9 (1.9) | 12.8 (2.0) | 13.1 (1.8) | 0.35 |
| Serum sodium, mEq/L | 139.4 (3.1) | 139.3 (3.2) | 139.6 (3.1) | 0.57 |
| Creatinine, mg/dL | 1.4 (1.0) | 1.5 (1.1) | 1.3 (0.7) | 0.040 |
| Blood urea nitrogen, mg/dL | 27.9 (18.1) | 29.2 (19.7) | 25.0 (13.8) | 0.17 |
| Estimated glomerular filtration rate, mL/min per 1.73 m2 | 65.3 (27.4) | 63.8 (27.1) | 69.2 (28.0) | 0.18 |
| Programmed zone (median and minimum–maximum), beats per min | ||||
| VF zone | 188 (170–316) | 188 (170–316) | 200 (185–220) | … |
| VTzone | 164 (150–194) (n=72) | 160 (150–194) (n=54) | 170 (140–182) (n=18) | … |
ACE indicates angiotensin-converting enzyme; EF, ejection fraction; ICD, implantable cardioverter-defibrillator; NYHA, New York Heart Association; VF, ventricular fibrillation; and VT, ventricular tachycardia.
*
Data are presented as mean (SD) or n (%) except when indicated otherwise.