QRS-T morphology measured from exercise electrocardiogram as a predictor of cardiac mortality (original) (raw)
Related papers
Annals of Noninvasive Electrocardiology, 2010
QRS/T angle and the cosine of the angle between QRS and T-wave vectors (TCRT), measured from standard 12-lead electrocardiogram (ECG), have been used in risk stratification of patients. This study assessed the possible rate dependence of these variables during exercise ECG in healthy subjects. Forty healthy volunteers, 20 men and 20 women, aged 34.6 +/- 3.4, underwent an exercise ECG testing. Twelve-lead ECG was recorded from each test subject and the spatial QRS/T angle and TCRT were automatically analyzed in a beat-to-beat manner with custom-made software. The individual TCRT/RR and QRST/RR patterns were fitted with seven different regression models, including a linear model and six nonlinear models. TCRT and QRS/T angle showed a significant rate dependence, with decreased values at higher heart rates (HR). In individual subjects, the second-degree polynomic model was the best regression model for TCRT/RR and QRST/RR slopes. It provided the best fit for both exercise and recovery. The overall TCRT/RR and QRST/RR slopes were similar between men and women during exercise and recovery. However, women had predominantly higher TCRT and QRS/T values. With respect to time, the dynamics of TCRT differed significantly between men and women; with a steeper exercise slope in women (women, -0.04/min vs -0.02/min in men, P < 0.0001). In addition, evident hysteresis was observed in the TCRT/RR slopes; with higher TCRT values during exercise. The individual patterns of TCRT and QRS/T angle are affected by HR and gender. Delayed rate adaptation creates hysteresis in the TCRT/RR slopes.
International Journal of Environmental Research and Public Health
Periodic repolarization dynamics (PRD) is a novel electrocardiographic marker of cardiac repolarization instability with powerful risk stratification capacity for total mortality and sudden cardiac death. Here, we use a time-frequency analysis approach to continuously quantify PRD at rest and during exercise, assess its dependence on heart rate variability (HRV) and characterize the effects of age (young adults/middle-aged adults/older adults), body mass index (non-overweight/overweight) and cardiorespiratory fitness level (fit/unfit). Sixty-six male volunteers performed an exercise test. RR and dT variabilities (RRV, dTV), as well as the fraction of dT variability unrelated to RR variability, were computed based on time-frequency representations. The instantaneous LF power of dT (PdTV), representing the same concept as PRD, and of its RRV-unrelated component (PdTVuRRV) were quantified. dT angle was found to mostly oscillate in the LF band. Overall, 50–70% of PdTV was linearly unrel...
Electrocardiographic Predictors of Cardiovascular Mortality
Disease Markers, 2015
Cardiovascular diseases are the main causes of mortality. Sudden cardiac death may also appear in athletes, due to underlying congenital or inherited cardiac abnormalities. The electrocardiogram is used in clinical practice and clinical trials, as a valid, reliable, accessible, inexpensive method. The aim of the present paper was to review electrocardiographic (ECG) signs associated with cardiovascular mortality and the mechanisms underlying those associations, providing a brief description of the main studies in this area, and consider their implication for clinical practice in the general population and athletes. The main ECG parameters associated with cardiovascular mortality in the present paper are the P wave (duration, interatrial block, and deep terminal negativity of the P wave in V1), prolonged QT and Tpeak-Tend intervals, QRS duration and fragmentation, bundle branch block, ST segment depression and elevation, T waves (inverted, T wave axes), spatial angles between QRS and...
Load dependent changes of cardiac depolarization and repolarization during exercise ECG test
Computing in Cardiology 2013, 2013
The trend of the morphology changes of cardiac depolarization and repolarization during exercise ECG test were examined in a group of 106 individuals. The ratio between the second and the first eigenvalues of Principal Component Analysis (PCA) was considered. The increasing and decreasing trends of PCA_QRS and PCA_T were classified as homogeneous and the rest as heterogeneous and their relationship with clinical data were studied. Depolarization: an increasing percentage of heterogeneous trends were observed in the groups with cardiac risk factors. This trend was statistically significant in the dyslipidemia disease (p<0.05). Repolarization: opposite to the depolarization, an increasing percentage of the homogeneous trends was obtained in the groups with cardiac risk factors, with statistically significant differences considering coronary artery disease and percutaneous coronary intervention (p<0.05). The study of the load dependent behavior of PCA index during the stress test has revealed an increasing percentage of homogeneous and heterogeneous trends respectively in T and QRS wave, which can help to a better characterization of the diagnostic value of the exercise test.
Journal of Electrocardiology, 2013
Analytical methods to measure T-wave alternans (TWA), a beat-to-beat fluctuation in the morphology of the ST-segment and T wave in the electrocardiogram (ECG), have been developed to address the unmet challenge of identifying individuals at increased risk for sudden cardiac death. Conventional noninvasive markers including left ventricular ejection fraction have significant limitations as many individuals who die suddenly have relatively preserved ventricular mechanical function. TWA is an attractive marker as it is closely linked to ECG heterogeneity and abnormalities in calcium handling, key factors in arrhythmogenesis. The objectives of this review are to summarize the clinical evidence supporting use of TWA in risk stratification and to discuss its current and potential applications in guiding device and medical therapy.
Behavior of Repolarization Variables during Exercise Test in the Athlete's Heart
Annals of Noninvasive Electrocardiology, 2012
Background: T peak-T end, QT peak/QT ratio and T peak-T end/QT ratio are markers able to test myocardial repolarization homogeneity, their increase has been related to a higher risk of ventricular tachyarrhythmias. These parameters have not yet been studied in left ventricular hypertrophy due to training. Aim of the research was to test the behavior of these variables in the athlete's heart during exercise. Methods: We examined 70 athletes, all males, divided into two groups according to the absence or the presence of a left ventricular mass index over 49 g/m 2.7 and a control group composed of 35 healthy, untrained males. All study participants underwent electrocardiogram at rest, transthoracic echocardiogram, and ergometric test. Repolarization markers (QT, corrected QT, QT dispersion, T peak-T end, QT peak/QT, T peak-T end/QT) were calculated at rest, at peak exercise and during recovery. Results: There was no statistically significant difference among the groups regarding all the parameters studied, except for corrected QT at rest between athletes with left ventricular hypertrophy and control group. The behavior of repolarization markers during exercise was not dissimilar in the three groups. Conclusions: Athlete's heart is not associated to any alteration in ventricular repolarization homogeneity, neither at rest nor during physical activity nor during recovery. Training-induced left ventricular hypertrophy does not affect relationship QT parameters/RR interval.