Table 1.
Baseline (1987–1989) participants characteristic stratified by spatial QRS/T angle groups and outcomes during follow-up (1996–1998).
| N = 9498 | Mean ± SD or n (%),
|
p-Valuec | p-Valued | ||
|---|---|---|---|---|---|
| Normal QRS/T (n = 7167) | Borderline QRS/T (n = 1851) | Wide QRS/T (n = 480) | |||
| Age (years) | 54 ± 5.7 | 54 ± 5.6 | 55 ± 5.7 | <.0001 | <.0001 |
| Women | 4085 (57) | 1038 (56) | 277 (58) | .3789 | .4835 |
| African-American | 1424 (19.9) | 356 (19.2) | 150 (31.3) | <.0001 | <.0001 |
| Education ≤ high school | 3644 (50.8) | 961 (51.9) | 266 (55.4) | .0180 | .2526 |
| Current smoker | 1407 (19.7) | 490 (26.5) | 117 (24.4) | <.0001 | .9251 |
| Body mass index (kg/m2) | 27 ± 4.9 | 27 ± 5.2 | 28 ± 5.8 | <.0001 | <.0001 |
| Systolic blood pressure (mm Hg) | 118 ± 16 | 120 ± 18 | 128 ± 23 | <.0001 | <.0001 |
| Hypertension | 1875 (26.3) | 518 (28.1) | 234 (49.0) | <.0001 | <.0001 |
| Antihypertensive medication | 1607 (22.4) | 408 (22.1) | 176 (36.7) | <.0001 | <.0001 |
| Diabetes | 528 (7.4) | 160 (8.7) | 73 (15.3) | <.0001 | <.0001 |
| Ratio of total/HDL cholesterol | 4.5 ± 1.6 | 4.5 ± 1.9 | 4.7 ± 1.7 | .0020 | <.0001 |
| Cholesterol lowering medication | 168 (2.4) | 43 (2.3) | 10 (2.1) | .5370 | .4862 |
| Aspirin use | 3218 (45.3) | 886 (48.3) | 222 (46.7) | .0100 | .5270 |
| Family history of coronary heart disease | 2861 (39.9) | 751 (40.6) | 187 (39.0) | .4380 | . 2177 |
| Serum creatinine (mg/dL) | 1.1 ± 0.3 | 1.1 ± 0.2 | 1.1 ± 0.2 | <.0001 | .0002 |
| Left ventricular hypertrophya | 90 (1.0) | 9 (2.8) | 7 (1.8) | <.0001 | <.0001 |
| QRS/T angle—spatial (°) | 55 ± 18 | 94 ± 11 | 127 ± 15 | <.0001 | <.0001 |
| QRS/T angle—frontal (°) | 19 ± 16 | 29 ± 24 | 56 ± 42 | <.0001 | <.0001 |
| Heart rate (beats/min) | 65 ± 9.5 | 67 ± 10 | 68 ± 11 | <.0001 | .0046 |
| QRS duration (ms) | 90 ± 9.1 | 93 ± 9.6 | 94 ± 10 | <.0001 | .0026 |
| QTrr interval (ms)b | 414 ± 14 | 416 ± 15 | 418 ± 16 | <.0001 | .0137 |
| Outcomes | |||||
| Silent myocardial infarction | 198 (2.8) | 85 (4.6) | 34 (7.1) | <.0001 | <.0001 |
| Clinical myocardial infarction | 274 (3.8) | 73 (3.9) | 39 (8.1) | <.0001 | <.0001 |
Left ventricular hypertrophy was defined by Cornell voltage criteria.
QTrr interval is the rate-adjusted QT interval as a linear function of the RR interval.
p-Value comparing three groups (Wide QRS/T angle for >95th percentile, Borderline QRS/T angle for >75th and ≤ 95th percentile, and Normal QRS/T angle for ≤75th percentile) with ternary level of QRS/T angle including ≤75th percentile using analysis of variance and Chi-squared for continuous and categorical variables, respectively.
p-Value comparing groups with wide QRS/T angle and borderline QRS/T angle using unpaired Student T test and chi-squared for continuous and categorical variables, respectively.