Widened QRS-T Angle May Be a Measure of Poor Ventricular Stretch During Exercise Among On-duty Firefighters.

Abstract

The spatial QRS-T angle is a measure of repolarization heterogeneity and may be a predictor of poor ventricular health. It is unknown whether a relationship exists between QRS-T angle and blood pressure (BP) during exercise. The purpose of this study was to evaluate the potential relationship between QRS-T angle and BP during exercise, which may be indicative of ventricular stretch. Ambulatory 12-lead 24-hour Holter electrocardiographic monitoring for QRS-T angle measurement was followed by exercise testing with BP (mm Hg) recordings taken preexercise, maximum achieved BP during exercise, and 2 minutes postexercise. Blood pressure recovery was calculated by subtracting the maximal and 2-minute postexercise BPs. Means (± standard deviation) and percentages are presented. Pearson correlations (r) among all QRS-T angles and all BP measures were performed. One-way analysis of variance was conducted on classification of QRS-T angle and all BP measures. One hundred eleven firefighters (95.5% male; mean age, 44 years) were included in this analysis. Twenty-seven percent of the firefighters had either a borderline (100°-139°) or widened (≥140°) QRS-T angle. Although the analysis of variance was not statistically significant, a near-statistically significant negative correlation existed between QRS-T angle and maximum diastolic BP (r = -0.190, P = .05), and a statistically significant relationship existed between QRS-T angle and postexercise diastolic BP (r = -0.261, P = .008). A negative correlation existed between QRS-T angle and maximal diastolic BP and postexercise diastolic BP. Lower maximum diastolic BP during and after exercise may be a sign of poor ventricular stretch. A widened spatial QRS-T angle may represent poor ventricular stretch.