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. Author manuscript; available in PMC: 2008 Sep 1.
Published in final edited form as: Am J Cardiol. 2007 Jun 18;100(5):844–849. doi: 10.1016/j.amjcard.2007.03.104

Table 1.

Baseline Characteristics of the Study Population Including Key Demographic, Clinical and Electrocardiographic Variables of Interest by Gender

Variables All Participants Men Women P
         
  (N=13,973) (N=5,908) (N=8,065) Value6
Percent (%)        
         
Gender (Women) 57.7%      
         
Race (Black) 26.7% 22.9% 29.6% <0.001
         
Hypertension1 33.4% 32.1% 34.4% 0.004
         
Diabetes Mellitus 10.9% 10.7% 11.1% 0.406
         
Angina Pectoris by Rose questionnaire 4.2% 2.5% 5.4% <0.001
         
LVH by Cornell Voltage2 2.1% 2.6% 1.8% 0.001
         
Major_ST Depression3 1.2% 1.3% 1.2% 0.710
         
Major_STT Abnormality3 4.2% 3.5% 4.7% <0.001
         
Mean + Standard Deviation        
         
Age (years) 54.4±5.7 54.8±5.8 54.2±5.7 <0.001
         
Heart Rate (beats/per min) 66.4±10.2 64.7±10.2 67.6±10.1 <0.001
         
QTrr (ms) 415.1±15.8 414.1±13.9 415.9±17.1 <0.001
         
Frontal plane QRS axis (degree)5 30.9±31.6 27.6±33.0 33.3±30.3 <0.001
         
Frontal plane T axis (degree)5 37.9±28.6 36.3±30.1 39.1±27.4 <0.001
         
QRS/T Spatial (degree)        
         
At 75th, 90th, 95th percentiles7 84, 104, 117 93, 112, 123 77, 96, 110  
         
  All Participants 67.2±28.0 75.2±27.7 61.4±26.8 <0.001
         
    Black8 69.1±31.0 81.8±29.1 61.8±29.7 <0.001
         
    White8 66.5±26.8 73.2±27.0 61.2±25.5 <0.001
         
QRS/T Frontal (degree)        
         
At 75th, 90th, 95th percentiles7 31, 51, 69 32, 54, 73 31, 50, 67  
         
  All Participants 23.9±24.0 24.7±25.1 23.3±23.1 0.001
         
    Black8 26.0±27.8 26.9±29.2 25.5±27.0 0.118
         
    White8 23.1±22.3 24.1±23.7 22.3±21.1 <0.001
         
T wave Axis Spatial (degree)        
         
At 75th, 90th, 95th percentiles7 32, 43, 54 32, 41, 51 32, 45, 56  
         
  All Participants 26.0±16.1 25.8±14.4 26.1±17.3 0.377
         
    Black8 31.8±18.9 32.3±17.4 31.4±19.8 0.158
         
    White8 23.8±14.4 23.9±12.8 23.8±15.6 0.793
(1)

Note: Hypertension at baseline (Systolic blood pressure ≥ 140 or diastolic blood pressure ≥ 90), or on antihypertensive medication.

(2)

Left Ventricular Hypertrophy by Cornell Voltage (CV = RaVL + SV3): LVH_CV cut point at CV ≥ 2200 for Women, and CV ≥ 2600 for Men.

(3)

Major ST Depression: Minnesota Code in 4.1 or 4.2. Major_STT Abnormality: Minnesota Code in 5.1 or 5.2; or 4.1 or 4.2;

(4)

The ECG variables were categorized as: abnormal (≥95th percentile), borderline (≥ 75th and < 95th percentile), and normal (<75th percentile), separately for men and women.

(5)

For Frontal plane QRS-axis or Frontal plane T-axis from the GE Marquette Program.

(6)

For significant statistical test between men and women.

(7)

The values of spatial QRS/T angle, frontal QRS/T angle and T wave axis at, 75th, 90th, 95th percentiles.

(8)

Among total 13,973 participants, 10,236 for White (45.5% for Men and 55.5% for Women), and 3,737 for Black (36.2% for Men and 63.8% for Women)