Exercise-induced Electrocardiographic Changes Research Articles

Exercise-Induced Electrocardiographic Changes in Healthy Young Males with Early Repolarization Pattern.

Background: Exercise-induced modifications in ECG parameters among individuals with an early repolarization pattern (ERP) have not been evaluated in detail. We aimed to assess this phenomenon, with potential associations with arrhythmogenesis. Methods: Twenty-three young, healthy males with ERP (ERP+) participated in this study, alongside a control group, which consisted of nineteen healthy males without ERP (ERP-). ECGs at baseline, at peak exercise (Bruce protocol), and during the recovery phase were analyzed and compared between the two groups. Results: The treadmill test demonstrated strong cardiovascular fitness, with similar chronotropic and pressor responses in both groups. In the baseline ECGs, the QRS complex and the QT interval were shorter in the ERP+ group. During exercise, the P-wave duration was significantly longer and the QRS was narrower in the ERP+ group. In the recovery phase, there was a longer P wave and a narrower QRS in the ERP+ group. During the treadmill test, the J wave disappeared or did not meet the criteria required for ERP diagnosis. Conclusions: The slowed intra-atrial conduction found during exercise could be predictive of atrial arrhythmogenesis in the setting of ERP. The disappearing of J waves during exercise, due to increased sympathetic activity, has potential clinical significance.

Exercise-induced electrocardiographic changes after treadmill exercise testing in healthy children: A comprehensive study.

Background:Treadmill exercise testing is a crucial diagnostic tool for evaluating congenital and acquired heart disease in the pediatric population. This study aimed to perform a comprehensive evaluation of exercise-induced electrocardiographic (ECG) changes in children. Although there are numerous studies on exercise testing in various cardiac pathologies, studies on exercise-induced ECG changes in normal children with coverage of all ECG parameters of atrial and ventricular depolarization and repolarization are very scant, if any.Aims and Objectives:This study aimed to investigate the exercise-induced ECG changes in healthy children and evaluate the effects of gender and four different formulas of heart rate correction of Bazett, Fridericia, Framingham and Hodges on ventricular repolarization parameters pre-and post-exercise.Materials and Methods:Between April 2019 and April 2020, all children with normal electrocardiogram, echocardiogram and exercise test, high-quality ECG tracings and consent for participation were enrolled in this prospective study. Twenty electrocardiographic parameters were measured and 25 indices were calculated. P-value < 0.05 was considered significant.Results:Seventy-four healthy children were studied. Amplitudes of P, S, and T waves increased significantly after the exercise. All durations, except P wave time to peak and T peak -T end /QT (Tp-e/QT) interval decreased significantly with exercise. Generally, the parameters of ventricular repolarization were not statistically significant between males and females. There were significant differences among the heart-rate corrected values of intervals of QTc, QoTc, JTc, J point to peak T and Tp-e/QTc by various formulas. There was no U wave either at pre-exercise or post-exercise. QT interval was shortened by 24.6 % ± 12.1 % with exercise. The ECG-derived estimated duration of mechanical systole and diastole decreased with exercise. The percentage of decrease in diastole was more than systole (43.79 %± 13.31% versus 33.74% ±15.79 %, respectively, P-value < 0.001).Conclusion:Diastolic time decreased more than systolic time with exercise and systolic time to diastolic time increased with exercise. Hodges' and Fridericia's formulas resulted in the longest and shortest QT and QoT, JT, and JTP, respectively. Thus, using a single value as the cut-off for long QT syndrome can lead to under or over-diagnosis. Nomograms incorporating data on age, heart rate, and heart rate correction formula are indispensable for accurate long QT diagnosis. Furthermore, gender differences in ventricular repolarization parameters are not generally present in 5 to 14-year-old healthy children. The lack of U wave in this study may implicate the need for more careful investigation in the presence of U wave in the treadmill exercise testing of healthy children.

Commentary

To aid in the study of coronary artery disease, 57 patients with complete left bundle branch block underwent clinical evaluation, treadmill exercise testing and cardiac catheterization. The patients were classified into two groups according to coronary anglographic findings: 30 patients with significant stenosis (70 percent or greater luminal narrowing) of at least one major vessel and 27 with no significant coronary artery disease. There was no difference in age, presenting symptoms or previous medical treatment between the two groups. There were more men in the group with coronary artery disease. Exercise-induced S-T changes were similar in the two groups; the sensitivity and specificity of these changes for the diagnosis of coronary artery disease were unacceptable irrespective of the criterion chosen. With additional S-T depression of either 1 or 2 mm below the baseline value, the predictive accuracy was only 53 percent. Combined exertional chest pain and 1 mm S-T depression increased the predictive accuracy of exercise testing to 71 percent. These data indicate that exercise-induced electrocardiographic changes do not facilitate detection of coronary artery disease in patients with complete left bundle branch block.

Effect of hormone replacement therapy on the electrocardiographic response to exercise

Background. Female gender and hormonal status affect electrocardiographic (ECG) response to exercise. Both are often cited as factors contributing to the decreased diagnostic accuracy of exercise stress tests in women. However, there is a paucity of data. To explore the relationship between hormonal status and exercise-induced ECG changes, we used gated single photon emission computed tomography (SPECT) technetium 99m sestamibi imaging for detection of myocardial ischemia. Methods and Results. ECG response to exercise was analyzed in all female patients who underwent symptom-limited exercise stress testing over a 12-month period with no evidence of ischemia on SPECT myocardial perfusion imaging (N = 404). Hormonal status was defined as premenopausal (n = 78), postmenopausal (n = 277), and postmenopausal on hormone replacement therapy (HRT) (n = 49). Positive ECG response for ischemia was defined as 1 mm or greater horizontal and/or downsloping ST depression during and/or after exercise. The frequency of a positive ECG response to exercise without evidence of ischemia on gated SPECT imaging was analyzed according to hormonal status. Seventeen of 78 premenopausal women (22%), 48 of 277 postmenopausal women (17%), and 19 of 49 women taking HRT (39%) had a positive ECG response. ECG positivity was significantly higher in HRT users when compared with premenopausal (P = .05) and postmenopausal women (P = .001). Conclusions. Exogenous estrogen replacement therapy affects ST-segment response to exercise, likely through a nonischemic mechanism. Unless HRT can be discontinued for a prolonged period of time (up to 6 weeks) prior to a stress test, myocardial imaging should be used to improve diagnostic accuracy. (J Nucl Cardiol 2002;9:385-7)

Significance of exercise-induced simultaneous ST-segment changes in lead aVR and V 5

This study was undertaken to investigate the ability of the exercise-induced ST depression in lead V 5 and concomitant ST elevation in lead aVR for the identification of the significantly narrowed coronary artery in patients with single vessel disease. We studied 229 consecutive patients who developed the aforementioned exercise-induced electrocardiographic changes. All underwent Thallium-201 scintigraphy and coronary arteriography. Patients were divided into three groups. In group A, 58 patients with ST depression in V 5 and ST elevation in aVR, in group B 149 patients with ST depression in V 5 without ST elevation in aVR, and in group C 22 patients with ST elevation in aVR without ST depression in V 5 induced with exercise, were included. In group A, 81% of the patients while in group B, 29% and in group C only 18% of the patients had left anterior descending artery disease. According to Thallium-201 scintigraphy, 80% of the group A, 27% of the group B and 12% of the group C patients developed myocardial ischemia in areas supplied by the left anterior descending artery. Thus, exercise-induced ST depression in V 5 and concomitant ST elevation in aVR, may detect left anterior descending artery significant stenosis in patients with single vessel disease.

Exercise Test Interpretation

The interpretation of an exercise test should encompass both subjective and objective aspects derived from testing. The patient's appearance, symptoms, and physical examination form an important part of the exercise test as do the hemodynamic responses of blood pressure and heart rate. In addition, the assessment of exercise capacity has been correlated to diagnosis and prognosis of patients with heart disease. Moreover, exercise-induced electrocardiographic changes provide the clinician with markers of cardiac pathology, which together with hemodynamic and clinical responses complete the exercise interpretation.

Effect of oral pentoxifylline in exercise-induced silent myocardial ischemia

Pentoxifylline, a methyl xanthine derivative with hemorheologic properties, has been used in the treatment of peripheral and cerebrovascular occlusive diseases. To assess its effect in myocardial ischemia, 20 patients with previous myocardial infarction and silent ischemia at exercise were randomized to receive pentoxifylline 1.2 gm/day or placebo during a 3-month double-blind trial. There were no differences in age, body mass index, or risk factors between groups. At the end of the study, patients in the placebo group showed no changes in physical work capacity or ST segment depression. In contrast, patients in the pentoxifylline group showed a slight but significant increase in physical work capacity (+0.24 ± 0.07 watts/kg; P < 0.01) and a decrease in both maximal exercise-induced ST segment depression (−0.80 ± 0.18 mm; P < 0.01) and at the ninth minute of recovery (−0.38 ± 0.13 mm; P < 0.05). The drug was generally well tolerated. We conclude that pentoxifylline diminishes exercise-induced electrocardiographic changes of myocardial ischemia and improves physical work capacity.

Influence of exercise-induced myocardial ischemia on the pattern of left ventricular diastolic filling: A Doppler echocardiographic study

Previous studies using Doppler echocardiography to evaluate left ventricular diastolic filling have shown that myocardial ischemia induced by coronary balloon angioplasty or atrial pacing results in a decrease in the left ventricular inflow peak early (E) to peak atrial (A) velocity ratio. To investigate the effects of exercise-induced ischemia on Doppler-derived filling variables, 20 patients with coronary artery disease and exercise-induced electrocardiographic changes and regional wall motion abnormalities determined by two-dimensional echocardiography were evaluated and compared with 20 patients without evidence of exercise-induced ischemia. Doppler echocardiography was performed at rest and immediately after exercise before the resolution of exercise-induced wall motion abnormalities. Peak E and A velocities increased from rest to postexercise in both the ischemic and nonischemic groups, although the ischemic group demonstrated a greater increase in peak E velocity (from 68 +/- 15 cm/s at rest to 88 +/- 22 cm/s after exercise) than the nonischemic group (70 +/- 13 to 77 +/- 18 cm/s) (p less than 0.05 for the difference in response between groups). Accompanying these changes was a slight increase in the peak E/A velocity ratio in the ischemic group (1.04 +/- 0.28 at rest to 1.13 +/- 0.42 after exercise) versus a decrease in the nonischemic group (1.07 +/- 0.30 to 0.90 +/- 0.28) (p less than 0.05 intergroup difference).(ABSTRACT TRUNCATED AT 250 WORDS)

Myocardial performance and perfusion during exercise in patients with coronary artery disease caused by Kawasaki disease

For a study of the natural history of coronary artery lesions after Kawasaki disease and their effect on myocardial blood flow reserve with exercise, five such patients underwent exercise testing on a bicycle. Oxygen consumption, carbon dioxide production, minute ventilation, and electrocardiograms were monitored continuously. Thallium-201 scintigraphy was performed for all patients. One patient stopped exercise before exhaustion of cardiovascular reserve but had no evidence of myocardial perfusion abnormalities. Four patients terminated exercise because of exhaustion of cardiovascular reserve; one had normal cardiovascular reserve and thallium scintiscans, but the remaining patients had diminished cardiovascular reserve. Thallium scintigrams showed myocardial ischemia in two and infarction in one. No patient had exercise-induced electrocardiographic changes. These results indicate that patients with residual coronary artery lesions after Kawasaki disease frequently have reduced cardiovascular reserve during exercise. The addition of thallium scintigraphy and metabolic measurements to exercise testing improved the detection of exercise-induced abnormalities of myocardial perfusion.

Is the treadmill exercise test useful for evaluating coronary artery disease in patients with complete left bundle branch block?

To aid in the study of coronary artery disease, 57 patients with complete left bundle branch block underwent clinical evaluation, treadmill exercise testing and cardiac catheterization. The patients were classified into two groups according to coronary anglographic findings: 30 patients with significant stenosis (70 percent or greater luminal narrowing) of at least one major vessel and 27 with no significant coronary artery disease. There was no difference in age, presenting symptoms or previous medical treatment between the two groups. There were more men in the group with coronary artery disease. Exercise-induced S-T changes were similar in the two groups; the sensitivity and specificity of these changes for the diagnosis of coronary artery disease were unacceptable irrespective of the criterion chosen. With additional S-T depression of either 1 or 2 mm below the baseline value, the predictive accuracy was only 53 percent. Combined exertional chest pain and 1 mm S-T depression increased the predictive accuracy of exercise testing to 71 percent. These data indicate that exercise-induced electrocardiographic changes do not facilitate detection of coronary artery disease in patients with complete left bundle branch block.

Exercise-induced electrocardiographic changes in children with congenital aortic stenosis

The relationship of exercise-induced electrocardiographic changes to severity of obstruction in congenital aortic stenosis was studied in 44 children. Twelve subjects, with ST segment depression of 1 mm or more lasting 0.08 seconds after the J Point, had left ventricular-aortic peak systolic pressure differences (gradients) ranging from 54 to 112 mm Hg. The remaining 32 children had less than 1 mm or no ST segment depression. Thirty-one of these had gradients ranging from 10 to 48 mm Hg and one had a gradient of 52 mm Hg. Vectorcardiograms, electrocardiograms, and chest roentgenograms were not useful in the identification of the severity of the lesion. The study suggests that children with severe gradients develop electrocardiographic ST segment changes with exercise, thereby helping to select those patients who should have catheterization studies to delineate the severity of the lesion. In those with a normal exercise test, cardiac catheterization may be safely delayed, but the exercise test should be repeated to identify those who develop progressive obstruction.

Myocardial infarction after exercise-induced electrocardiographic changes in a patient with variant angina pectoris

The electrocardiographic response to stress testing varies considerably in patients with variant angina pectoris: no change in the S-T segment as well as S-T segment depression and elevation have been observed. This report describes a patient with a resting ST-T abnormality that reverted to normal appearance with exercise. However, the patient experienced severe chest pain shortly after discontinuing exercise testing, and an electrocardiogram showed evidence of acute anterolateral infarction. The possible implications of such electrocardiographic changes are discussed.