The relationship between QT dispersion and exaggerated blood pressure response to exercise stress testing

Diagnostic Value of Electrocardiogram in Predicting Exaggerated Blood Pressure Response to Exercise Stress Testing

INTRODUCTION

It is believed that an exaggerated blood pressure response (EBPR) to exercise stress test is associated with a higher risk of cardiovascular events. It is also assumed that QT dispersion (QT-d), which was originally proposed to measure the spatial dispersion of ventricular recovery times, may have a relationship to cardiovascular events. The objective of this study was to examine the difference of changes in QT-d, Maxi-QT, Mini-QT, and QT-c (corrected QT interval) of the electrocardiogram in two groups of patients with exaggerated blood pressure responses (EBPR group) and normal responses (control group) to exercise testing. Also, the diagnostic value of each of these criteria in the prediction of EBPR was studied.

METHODS

This cross-sectional study was conducted from May 2015 to February 2016 on patients suspected of coronary artery disease (CAD) undergoing exercise testing who had been referred to Ghaem and Imam Reza hospitals in Mashhad (Iran). All patients underwent a treadmill exercise test with the 12-lead ECG, which was optically scanned and digitized for analysis of QT-d, QT max, and QT min. Patients were divided into two groups of normal and EBPR to exercise testing. QT changes of ECG were compared between the two groups, and the diagnostic accuracy of QT variables for prediction of EBPR to exercise testing was studied. A multiple linear regression analysis (MLR), Pearson Chi-qquare, independent samples t-test, and receiver operating characteristic (ROC) curve were used as statistical methods in IBM SPSS version 19.

RESULTS

Sixty patients (55% male) with a mean age of 50.48 ± 10.89 years were studied in two groups of normal (n=30) and exaggerated blood pressure response (n=30) to exercise testing. Maximum QT and QT dispersion were statistically different in individuals' exaggerated blood pressure response to exercise stress test (p < 0.05). The logistic regression analysis revealed that none of our parameters predicted the EBPR. The ROC curve showed that 50 and 345 milliseconds for QT dispersion and Maxi-QT were the optimal cut-off points for the prediction of EBPR.

CONCLUSION

It seems that Maxi-QT and QT-d may be predictors of EBPR during exercise testing. Also, a significant difference in maxi-QT and QT-d was observed between two groups of patients with normal and EBPR during the exercise testing.

Blood pressure control and exaggerated blood pressure response in nigerians with essential hypertension

BACKGROUND

Blood pressure (BP) control in hypertensives is important in preventing cardiovascular (CV) morbidity and mortality. This work was done to assess control of BP among Nigerian hypertensives at rest and during exercise.

MATERIALS AND METHODS

A total of 85 male hypertensives were recruited consecutively and had clinical evaluation and treadmill (TM) exercise testing using the Bruce protocol. Independent t-test, chi-square, and Fisher’s exact tests were used to compare patients with controlled and uncontrolled BP using SPSS version 16 software. Adjustment for confounders was by logistic regression and general linear model.

RESULTS

Resting systolic BP (rSBP) (mmHg) and resting diastolic BP (rDBP) (mmHg) were significantly lower in the controlled group (115.0 ± 12.29, 133.1 ± 12.27, P = <0.001 and 76.00 ± 6.55, 91.4 ± 8.00, P = <0.001). The proportion of subjects with controlled BP was 37.7%. Adjusted peak SBP (PSBP) during exercise (mmHg) was significantly higher in the uncontrolled than in the controlled group (210.5 ± 27.31, 191.8 ± 20.77, P = 0.001). Adjusted exaggerated blood pressure response (EBPR) was found in 37 subjects (44%) in the uncontrolled group while seven subjects (0.1%) had EBPR in the controlled group (P = 0.003).

CONCLUSION

This study shows that EBPR is significantly higher in subjects with uncontrolled BP compared with those with controlled BP. Therefore, good BP control may be the key factor in preventing EBPR in hypertensives.