Table 2.
Clinical features by QT-500 subgroup
| All | QT-500≤316 ms | QT-500>316 ms | p | |
|---|---|---|---|---|
| N | 2,994 | 2,484 | 510 | N/A |
| QT at 500 ms | 305 ± 16 | 300 ± 11 | 330 ± 14 | N/A |
| QT at 600 ms | 344 ± 20 | 338 ± 14 | 372 ± 19 | <0.0001 |
| QT-RR slope | 0.387 ± 0.105 | 0.381 ± 0.087 | 0.419 ± 0.165 | <0.0001 |
| Age (years) | 56.1 ± 11.6 | 55.8 ± 11.5 | 57.5 ± 12.3 | 0.0041 |
| Male | 1763 (58.9%) | 1484 (59.7%) | 279 (54.7%) | 0.035 |
| BMI (kg/m2)* | 28.5 ± 6.0 | 28.2 ± 5.8 | 29.6 ± 6.7 | <0.0001 |
| Diabetes | 380 (12.7%) | 264 (10.6%) | 116 (22.7%) | <0.001 |
| Family history of CAD | 759 (25.4%) | 641 (25.8%) | 118 (23.1%) | NS |
| Hyperlipidemia | 1251 (41.8%) | 1038 (41.8%) | 213 (41.8%) | NS |
| Hypertension | 1191 (39.8%) | 936 (37.7%) | 255 (50.0%) | <0.001 |
| Tobacco use | 443 (14.8%) | 357 (14.4%) | 86 (16.9%) | NS |
| Known CAD | 592 (19.8%) | 449 (18.1%) | 143 (28.0%) | <0.001 |
| s/p CABG | 240 (8.0%) | 167 (6.7%) | 73 (14.3%) | <0.001 |
| s/p MI | 255 (8.5%) | 190 (7.6%) | 65 (12.7%) | <0.001 |
| s/p PCI | 344 (11.5%) | 276 (11.1%) | 68 (13.3%) | NS |
| Resting HR (bpm)** | 71.0 ± 12.0 | 70.8 ± 11.8 | 72.6 ± 13.4 | 0.0062 |
| 60s HRR (bpm) | 21.1 ± 9.7 | 22.4 ± 9.3 | 15.2 ± 9.6 | <0.0001 |
| No CV Medications | 987 (33.0%) | 863 (34.7%) | 124 (24.3%) | <0.001 |
| Antiplatelets | 1042 (34.8%) | 853 (34.3%) | 189 (37.1%) | NS |
| Beta-blockers | 745 (24.9%) | 575 (23.1%) | 170 (33.3%) | <0.001 |
| ACE-I | 468 (15.6%) | 369 (14.9%) | 99 (19.4%) | 0.01 |
| Anticholesterol agents | 1049 (35.0%) | 833 (33.5%) | 216 (42.4%) | <0.001 |
| CCB | 375 (12.5%) | 296 (11.9%) | 79 (15.5%) | 0.026 |
| Diuretics | 365 (12.2%) | 268 (10.8%) | 97 (19.0%) | <0.001 |
| Exercise time (min) | 9.9 ± 3.3 | 10.1 ± 3.2 | 8.9 ± 3.4 | <0.0001 |
| Peak HR* SBP*** | 28015 ± 5429 | 28273 ± 5236 | 26504 ± 6245 | <0.0001 |
| Gated EF (%)**** | 58.7 ± 10.2 | 59.0 ± 9.9 | 57.4 ± 11.6 | 0.0048 |
| Summed stress score (SSS) | 2.9 ± 5.7 | 2.6 ± 5.3 | 4.3 ± 7.0 | <0.0001 |
| Summed rest score (SRS) | 1.0 ± 3.4 | 0.8 ± 3.1 | 1.7 ± 4.6 | <0.0001 |
| SDS=SSS-SRS | 1.9 ± 3.9 | 1.8 ± 3.7 | 2.6 ± 4.6 | <0.0001 |
*
BMI only available for 2,940 (98.2%) patients (Normal=2442, Abnormal=498)
**
resting HR only available for 2,712 (90.6%) patients (Normal=2318, Abnormal=394)
***
peak HR*SBP only available for 2,719 (90.8%) patients (Normal=2323, Abnormal=396)
****
gated EF only available for 2,240 (74.8%) patients (Normal=1829, Abnormal=411)