P1504Impact of myocardial ischemia induced by exercise stress echocardiography on the QT dispersion in patients with the left bundle branch block

Abstract Background/Introduction ECG has always provided very useful information that can be used to diagnosis, treatment and prevention of cardiovascular events, but ECG changes is not useful to the detection of myocardial ischemia in patients with left bundle branch block (LBBB). QT dispersion (QTd) is a measure of inhomogeneous repolarization of myocardium. Abnormally high QTd has been correlated with risk of cardiac death in coronary patients. Purpose The aim of this study was to establish the impact of myocardial ischemia induced by exercise stress echocardiography on the QT dispersion in patients with the left bundle branch block. Methods The study involved 123 patients with LBBB, average age 52.7 years. In all subjects clinical examination, standard ECG and exercise stress echocardiography, were performed. The criterion for myocardial ischemia was the appearance of transient segmental wall motion abnormality. The first ECG was done before the exercise stress echocardiography and the second one was done immediately after exercise, with calculation of corrected QT dispersion (QTdc). Results During exercise stress echocardiography, in 45 (36.6%) subjects wall motion abnormality occurred (group with myocardial ischemia: MI), and 78 (63.4%) subjects were without ischemia (group without myocardial ischemia: NMI). Before starting the exercise stress echocardiography, MI group patients had significantly higher values of QTdc (61.2±17.6 vs 43.6±15.4 ms; p<0.001) in comparison to NMI group patients. During the exercise stress echocardiography, the QTdc significantly increased in MI group from 61.2±17.6 to 87.4±20.3 ms (p<0.001). In the NMI group there were no significant changes in the values QTdc during exercise stress echocardiography (from 43.6±15.4 to 46.5±19.8 ms (p - NS). Conclusions Significant increase of QT dispersion is associated with the occurrence of myocardial ischemia during exercise stress echocardiography in patients with LBBB. This new diagnostic approach, of using QT dispersion, significantly improves the clinical usefulness of exercise stress echocardiography in detecting myocardial ischemia in patients with LBBB.

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Frequency and characteristics of myocardial ischemia recorded during stress echocardiography in patients with high coronary risk

Vojnosanitetski pregled ◽

10.2298/vsp1105393i ◽

2011 ◽

Vol 68 (5) ◽

pp. 393-398 ◽

Cited By ~ 2

Author(s):

Stevan Ilic ◽

Marina Deljanin-Ilic ◽

Viktor Stoickov

Keyword(s):

Myocardial Ischemia ◽

Stress Echocardiography ◽

Wall Motion ◽

Exercise Stress ◽

Silent Myocardial Ischemia ◽

Coronary Risk ◽

Wall Motion Score Index ◽

Exercise Stress Echocardiography ◽

Asymptomatic Subjects ◽

Score Index

Background/Aim. Ischemic heart disease is the major cause of morbidity and mortality in the world as well as in our country. Ischemic heart disease has the multifactorial origin and the presence of several risk factors increases the risk of myocardial ischemia. The aim of the study was to evaluate the frequency and characteristics of myocardial ischemia in asymptomatic subjects with two or more risk factors for coronary artery disease during stress echocardiography. Methods. In 240 high risk asymptomatic subjects (an absolute risk of fatal cardiovascular disease of more than 5%, according to the Systemic Coronary Risk Evaluation Chart), the exercise stress echocardiography test was performed. The criterion for myocardial ischemia was the appearance of transient segmental wall motion abnormality (WMA). The wall motion score index was calculated before and after the exercise stress echocardiography. Results. During exercise stress echocardiography, in 36 (15%) subjects WMA occurred. Out of 36 subjects with myocardial ischemia, in 10 (27.8%) subjects WMA and ST segment depression were accompanied with the first occurrence of chest pain (the subgroup with symptomatic myocardial ischemia), in 20 (55.6%) subjects WMA and ST segment depression were detected and in 6 (16.6%) subjects only WMA occurred (the subgroup with silent myocardial ischemia). There were no significant differences between the subgroups with symptomatic and silent myocardial ischemia with regard to exercise tolerance, heart rate at the onset of WMA, and time to the onset of WMA, but the wall motion score index was significantly higher in the subjects with symptomatic myocardial ischemia (p < 0.01). In all the individuals with symptomatic myocardial ischemia, significant stenosis of the coronary arteries was found by coronary angiography. Out of 26 subjects with asymptomatic myocardial ischemia, coronary angiography was performed in 18 and significant stenosis of the coronary arteries was diagnosed in all of them. The number and grade of coronary stenosis in subjects with symptomatic and silent myocardial ischemia were similar. Conclusion. The obtained results presented the incidence of myocardial ischemia in 15% of asymptomatic subjects with high coronary risk during stress echocardiography. Silent myocardial ischemia was markedly more frequent than symptomatic one, but in the subjects with symptomatic ischemia, the wall motion score index was significantly higher.

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