Table 1.
Baseline Characteristics, ECG parameters and LVEF Among Cases and Controls
| Total Subjects (n=1529) | |||
|---|---|---|---|
| Variable | Cases (n=666) | Controls (n=863) | P value |
| Age, yrs | 67.2 (52.3–82.1) | 66.6 (55.2–78.0) | 0.403 |
| Male gender | 457 (68.6) | 588 (68.1) | 0.84 |
| Hypertension | 495 (74.3) | 590 (68.6) | 0.015 |
| Diabetes mellitus | 269 (40.4) | 228 (26.5) | <0.0001 |
| Total cholesterol, mg/dL* | 176.7 (126.9–226.5) | 173.1 (128.3–217.9) | 0.231 |
| Previous MI | 280 (42.0) | 303 (35.2) | 0.007 |
| Heart rate, bpm | 78.5 (59.9–97.1) | 68.2 (53.2–83.2) | <0.0001 |
| QRS duration, ms | 102.8 (77.9–127.7) | 98.1 (77.1–119.1) | <0.0001 |
| Prolonged intraventricular conduction |
176 (26.4) | 163 (18.9) | <0.0001 |
| LBBB | 44 (25.0) | 38 (23.3) | |
| RBBB | 50 (28.4) | 59 (36.2) | |
| Others | 82 (46.6) | 66 (40.5) | |
| ECG LVH | 114 (17.1) | 103 (11.9) | 0.004 |
| Abnormal QRS axis | 168 (25.2) | 153 (17.7) | 0.0004 |
| Left-axis deviation | 115 (17.3) | 115 (13.3) | |
| Right-axis deviation | 37 (5.6) | 33 (3.8) | |
| Extreme QRS axis | 16 (2.4) | 5 (0.6) | |
| Abnormal T axis | 73 (11.0) | 87 (10.1) | 0.577 |
| QRS-T angle, ° | 74.0 (17.4–130.6) | 51.0 (4.8–97.2) | <0.0001 |
| LVEF, %† | 49.2 (32.9–65.5) | 53.9 (40.7–67.1) | <0.0001 |
| Severely impaired LVEF† | 82 (24.8) | 54 (13.4) | <0.0001 |
Data are presented as n (%) or mean (95% CI). Bpm denotes beats per minute; LBBB, left bundle branch block; LVEF, left ventricular ejection fraction; ECG LVH, electrocardiographic left ventricular hypertrophy; MI, myocardial infarction; RBBB, right bundle branch block.
Prolonged intraventricular conduction defined as QRS duration (QRSD) >110ms; LBBB and RBBB, in accordance to published recommendations;19 Others include incomplete LBBB, incomplete RBBB and non-specific intraventricular disturbance; ECG LVH, satisfying either Sokolow-Lyon (RV1 +SV5,6 ≥35mm) or Cornell criteria (RaVL + SV3 >20mm in females and >28mm in males)23,24; Abnormal QRS axis, <−30° or >90°; Left-axis deviation, −31° to −90°; Right-axis deviation, 91° to 180°; Extreme QRS axis, 181° to 269°; Abnormal T-wave axis, <−15° or >105°; Severely impaired LVEF, ≤35%.
Information on total cholesterol levels was available for 402 cases and 710 controls. Proportions and P values were calculated using the non-missing data as the denominator.
Information on LVEF was available for 330 cases and 402 controls. Proportions and P values were calculated using the non-missing data as the denominator.