Table 1.
Baseline characteristics of MRFIT participants hypertensive at entry, by clinic grouping.
| Variable | C-clinics | H-clinics | Switching- clinics |
Total |
|---|---|---|---|---|
| Number of participants | 2112 | 3399 | 2501 | 8012 |
| Age (years)* | 46.8 (5.8) | 46.7 (5.9) | 46.6 (5.9) | 46.7 (5.9) |
| Black (%) | 10.0 | 10.7 | 5.5 | 8.9 |
| Smoker (%) | 58.6 | 56.1 | 50.9 | 55.1 |
| Serum cholesterol (mg/dl)* | 249.3 (36.6) | 249.7 (36.6) | 251.7 (34.4) | 250.2 (35.9) |
| Body mass index (kg/m2)* | 27.8 (3.4) | 28.0 (3.5) | 28.0 (3.5) | 28.0 (3.5) |
| Systolic blood pressure (mm Hg)* | 142.0 (13.1) | 141.5 (13.1) | 140.2 (12.5) | 141.2 (12.9) |
| Diastolic blood pressure (mm Hg)* | 95.8 (6.9) | 95.5 (6.7) | 95.3 (6.6) | 95.5 (6.7) |
| Potassium (mmol/L)* | 4.36 (0.46) | 4.37 (0.48) | 4.38 (0.44) | 4.37 (0.46) |
| On antihypertensive medication (%) | 31.3 | 31.0 | 30.9 | 31.1 |
| Left ventricular hypertrophy (%), by Minnesota code |
2.3 | 2.7 | 2.3 | 2.5 |
| Electrocardiographic Measurement | ||||
| Absolute maximum of R amplitude V5/6 (μV)* | 1702.0 (515.4) | 1677.8 (530.9) | 1726.1 (525.2) | 1699.4 (525.4) |
| Absolute S amplitude V1 (μV)* | 947.4 (461.5) | 979.3 (461.6) | 921.3 (445.4) | 952.7 (457.2) |
| R amplitude aVL (μV)* | 290.3 (251.3) | 271.0 (251.5) | 268.4 (240.8) | 275.3 (248.3) |
| Absolute S amplitude V3 (μV)* | 1031.3 (467.6) | 1065.2 (467.6) | 1019.6 (463.7) | 1042.0 (466.8) |
| QRS duration (ms) | 85.3 (9.4) | 84.7 (9.6) | 85.5 (9.3) | 85.1 (9.4) |
| Criteria for Electrocardiographic Left Ventricular Hypertrophy | ||||
| Sokolow-Lyon (SL) (μV)* | 2649.4 (789.4) | 2657.3 (788.3) | 2647.3 (768.4) | 2652.1 (782.3) |
| Cornell voltage (μV)* | 1322.1 (527.0) | 1336.2 (528.5) | 1288.1 (517.6) | 1317.4 (525.1) |
| Cornell voltage product (μV/ms)* | 113.9 (49.8) | 114.5 (50.7) | 111.3 (49.1) | 113.3 (50.0) |
| Left ventricular mass (gm)* | 178.0 (21.6) | 177.4 (22.6) | 178.9 (21.4) | 178.0 (21.9) |
*
mean (S.D.)
Formulas: Sokolow-Lyon voltage (μV) = ∣SV1∣ + max ∣RV5/V6∣
Cornell voltage (μV) = SV3 + RaVL
Cornell voltage product (μV/ms) = Cornell voltage * QRS duration
Left ventricular mass (white men): 0.023 Cornell voltage + 0.010 Sokolow-Lyon + 1.32 weight + 10.6
Left ventricular mass (black men): 0.0018 Cornell voltage + 0.51 JV5 + 1.45 weight + 17.4