Association of myocardial bridge with ECG markers (QT andTp-e) in patients with suspected coronary artery disease

Background: Myocardial bridge describes bands of cardiac muscle fibres, which bridge across
the coronary arteries and their main branches. It is considered as a congenital anatomical variant.
It had been largely overlooked as a potential aetiology for pathology. This altered anatomic
course might influence the development of atherosclerosis. Myocardial bridges may cause
coronary heart disease either by constricting the underlying artery during cardiac systole or
inducing atherosclerotic changes in the artery proximal to the myocardial bridge. The degree of
coronary impediment depends on the position, length and thickness of the muscle bridges.
Aim of the study: To investigate the potential association of myocardial bridge assessed by
multidetector Computerized tomography with Electrocardiogram markers of arrhythmia.
Patient &methods: This was a cross-sectional study conducted at Al-Sader Teaching Hospital
during the period from January to September 2018 included 400 patients with intermediate pretest
probability of ischemic heart disease , who underwent 64-multislice multidetector
Computerized tomography angiography examination for the assessment of myocardialbridge were
enrolled in this study and attempt to show an association between patients electrocardiographic
parameters and myocardial bridge characters. A detailed history of traditional cardiac risk factors
for coronary artery disease was taken from each patient at the time of admission. Patients with a
heart rate more than65 beat per minute , known allergies to iodinated contrast agent, renal
insufficiency, pregnancy, respiratory failure, unstable clinical conditions, and severe heart failure
are excluded from study. Data are analyzed using the Statistical Package for the Social Sciences
(SPSS).
Results: Among the 400 patients, 47 (11.75%) myocardial bridges were detected; 6 were
excluded because of incomplete data. One bridge was found in 39 of these patients, and multiple
bridges were observed in 2 patients. The average length and thickness of myocardial bridge was
21.4±9.4 mm and 3.5±1.7mm, respectively. It had been significantly found that coronary artery
disease, plaque and stenosis increase as depth increases. No significant association was found
between depth with each of Tp-e interval and Transmural dispersion of repolarization. No
significant association was found between myocardial bridge length and each of coronary plaque
presence & coronary artery stenosis severity; while myocardial bridge length had moderately
significant correlation with coronary artery calcification, Tp-e interval and transmural dispersion
of repolarization.
Conclusion: The myocardial bridge is common and it is slightly more common in males than
females .We should not depend on QT interval in patients with myocardial bridge as predictor of
ventricular arrhythmia. In all patients with myocardial bridge, the Tp-e interval and transmural
dispersion of repolarization should be measured as an indicators for ventricular arrhythmia and
sudden death. Coronary artery disease and calcification.