Table 1.
Baseline Patient, hospital, Operator, and Procedure Characteristics
| PR<230 ms (n=22 416) |
PR≥230 ms (n=4035) |
P Value | |
|---|---|---|---|
| Age, y | 75.1 (6.0) | 76.9 (6.2) | <0.0001 |
| Sex, n (%) | |||
| Male | 14 620 (65.2) | 3329 (82.5) | <0.0001 |
| Female | 7796 (34.8) | 706 (17.5) | |
| Race, n (%) | |||
| White non-Hispanic | 19 503 (87.0) | 3610 (89.5) | <0.0001 |
| Black non-Hispanic | 1572 (7.0) | 244 (6.0) | |
| Hispanic | 892 (4.0) | 106 (2.6) | |
| Other | 449 (2.0) | 75 (1.9) | |
| QRS duration, ms | |||
| 120–129 | 3134 (14.0) | 504 (12.5) | <0.0001 |
| 130–139 | 3360 (15.0) | 587 (14.5) | |
| 140–149 | 4046 (18.0) | 625 (15.5) | |
| 150–159 | 4050 (18.1) | 603 (14.9) | |
| 160–169 | 3725 (16.6) | 686 (17.0) | |
| ≥170 | 4101 (18.3) | 1030 (25.5) | |
| Intraventricular conduction, n (%) | |||
| Non–left bundle-branch block | 7031 (31.4) | 1513 (37.5) | <0.0001 |
| Left bundle-branch block | 15 385 (68.6) | 2522 (62.5) | |
| Nonischemic cardiomyopathy | |||
| Missing | 18 (0.1) | 8 (0.2) | <0.0001 |
| No | 14 396 (64.2) | 2980 (73.9) | |
| Yes, within the past 9 mo | 2539 (11.3) | 291 (7.2) | |
| Yes, >9 mo | 5463 (24.4) | 756 (18.7) | |
| Ischemic heart disease, n (%) | 14 909 (66.5) | 3034 (75.2) | <0.0001 |
| Atrial fibrillation/atrial flutter, n (%) | 3871 (17.3) | 1106 (27.4) | <0.0001 |
| Ventricular tachycardia, n (%) | 3849 (17.2) | 745 (18.5) | 0.1006 |
| Primary prevention | 21 302 (95.0) | 3839 (95.1) | 0.7624 |
| New York Heart Association class | |||
| Missing | 14 (0.1) | 4 (0.1) | 0.077 |
| I | 1116 (5.0) | 169 (4.2) | |
| II | 5523 (24.6) | 983 (24.4) | |
| III | 15 164 (67.6) | 2751 (68.2) | |
| IV | 599 (2.7) | 128 (3.2) | |
| Previous percutaneous coronary intervention | 7380 (32.9) | 1388 (34.4) | 0.1546 |
| Previous coronary artery bypass grafting | 8612 (38.4) | 1999 (49.5) | <0.0001 |
| Diabetes mellitus | 8323 (37.1) | 1726 (42.8) | <0.0001 |
| Previous myocardial infarction | 11 746 (52.4) | 2395 (59.4) | <0.0001 |
| Chronic lung disease | 5201 (23.2) | 809 (20.0) | <0.0001 |
| Cerebrovascular disease | 3302 (14.7) | 706 (17.5) | <0.0001 |
| Cardiac arrest | 452 (2.0) | 73 (1.8) | 0.4454 |
| Hypertension | 17 567 (78.4) | 3213 (79.6) | 0.1129 |
| Syncope | 2315 (10.3) | 461 (11.4) | 0.0324 |
| Congestive heart failure duration | |||
| Missing | 25 (0.1) | 6 (0.1) | 0.0001 |
| No | 2166 (9.7) | 362 (9.0) | |
| <9 mo | 5682 (25.3) | 904 (22.4) | |
| >9 mo | 14 543 (64.9) | 2763 (68.5) | |
| Ejection fraction, % | 24.8 (6.3) | 25.2 (6.1) | <0.0001 |
| Glomerular filtration rate | |||
| Missing | 94 (0.4) | 14 (0.3) | <0.0001 |
| >60 mL·min−1·1.73m2 | 9473 (42.3) | 1426 (35.3) | |
| 30–59 mL·min−1·1.73m2 | 10 782 (48.1) | 2127 (52.7) | |
| 15–29 mL·min−1·1.73m2 | 1386 (6.2) | 328 (8.1) | |
| <15 mL·min−1·1.73 m2 including those on dialysis | 681 (3.0) | 140 (3.5) | |
| Dialysis | 581 (2.6) | 129 (3.2) | 0.0901 |
| Blood urea nitrogen level, mg/dL | |||
| Missing | 126 (0.6) | 22 (0.5) | <0.0001 |
| ≤ 20 | 9642 (43.0) | 1380 (34.2) | |
| 20–40 | 10 498 (46.8) | 2060 (51.1) | |
| >40 | 2150 (9.6) | 573 (14.2) | |
| Sodium level, mEq/L | |||
| Missing | 141 (0.6) | 23 (0.6) | 0.0641 |
| ≤135 | 2689 (12.0) | 521 (12.9) | |
| 135–145 | 19 327 (86.2) | 3429 (85.0) | |
| >145 | 259 (1.2) | 62 (1.5) | |
| Systolic blood pressure, mm Hg | |||
| Missing | 88 (0.4) | 17 (0.4) | 0.284 |
| ≤ 100 | 1178 (5.3) | 188 (4.7) | |
| 100–130 | 9235 (41.2) | 1635 (40.5) | |
| >130 | 11 915 (53.2) | 2195 (54.4) | |
| Cardiac resynchronization therapy | 15 994 (71.4) | 2906 (72.0) | 0.3864 |
| Angiotensin-converting enzyme inhibitor | 13 765 (61.4) | 2362 (58.5) | 0.0006 |
| Amiodarone | 1751 (7.8) | 574 (14.2) | <0.0001 |
| Hydralazine | 820 (3.7) | 194 (4.8) | 0.0005 |
| Angiotensin receptor blocker | 4597 (20.5) | 879 (21.8) | 0.0654 |
| Aspirin | 16 373 (73.0) | 2900 (71.9) | 0.1238 |
| β-Blocker | 19 583 (87.4) | 3471 (86.0) | 0.0192 |
| Warfarin | 3636 (16.2) | 978 (24.2) | <0.0001 |
| Digoxin | 4729 (21.1) | 1017 (25.2) | <0.0001 |
| Diuretic | 15 122 (67.5) | 2900 (71.9) | <0.0001 |
| Long-acting nitrate | 2659 (11.9) | 539 (13.4) | 0.0073 |
| Clopidogrel | 5391 (24.0) | 980 (24.3) | 0.7451 |
| Statin | 15 348 (68.5) | 2864 (71.0) | 0.0015 |
| Dementia | 605 (2.7) | 120 (3.0) | 0.3246 |
| Disability/frailty | 1378 (6.1) | 277 (6.9) | 0.0832 |
| Operator Training | |||
| Unknown | 4593 (20.5) | 817 (20.2) | 0.2905 |
| Board-certified EP/EP fellowship | 14 143 (63.1) | 2596 (64.3) | |
| Surgeon | 194 (0.9) | 38 (0.9) | |
| Other | 3486 (15.6) | 584 (14.5) | |
| Operator cardiac resynchronization therapy volume, implants/y | |||
| ≤ 20 | 12 439 (55.5) | 2208 (54.7) | 0.3648 |
| >20 | 9977 (44.5) | 1827 (45.3) | |
| Region | |||
| Other | 598 (2.7) | 128 (3.2) | 0.2015 |
| New England | 982 (4.4) | 180 (4.5) | |
| Atlantic | 7528 (33.6) | 1287 (31.9) | |
| Central | 10 599 (47.3) | 1936 (48.0) | |
| Mountain | 932 (4.2) | 167 (4.1) | |
| Pacific | 1777 (7.9) | 337 (8.4) | |
| Teaching status | |||
| Unknown | 594 (2.6) | 128 (3.2) | 0.1194 |
| Council of teaching hospitals | 6475 (28.9) | 1112 (27.6) | |
| Teaching hospital | 6276 (28.0) | 1141 (28.3) | |
| Not teaching hospital | 9071 (40.5) | 1654 (41.0) | |
| Center cardiac resynchronization therapy volume, implants/y | |||
| ≤20 | 2179 (9.7) | 343 (8.5) | 0.0151 |
| >20 | 20 237 (90.3) | 3692 (91.5) | |
| Beds set up and staffed | |||
| Unknown | 594 (2.6) | 128 (3.2) | 0.0443 |
| ≤100 | 1185 (5.3) | 221 (5.5) | |
| 101–500 | 13 093 (58.4) | 2404 (59.6) | |
| >500 | 7544 (33.7) | 1282 (31.8) | |
| Implant year | |||
| 2006 | 3926 (17.5) | 741 (18.4) | 0.0015 |
| 2007 | 4299 (19.2) | 871 (21.6) | |
| 2008 | 4933 (22.0) | 853 (21.1) | |
| 2009 | 4863 (21.7) | 832 (20.6) | |
| 2010 | 4395 (19.6) | 738 (18.3) | |
The values shown are n (%), unless stated otherwise. EP indicates electrophysiology.