الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Ischemic heart disease [IHD] is the primary single cause of left ventricular systolic dysfunction leading to heart failure.
The assessment of myocardial viability has become an integrated part of the diagnosis of patients with chronic ischemic heart disease. The available evidence suggests that patients with preserved viability will show improvement in function and symptoms after revascularization. In contrast, patients without viability will not benefit from revascularization, and the high risk of surgery should be avoided.
With recent technical advances in the field of cardiovascular MR imaging, there will be an increased demand for clinical cardiac MR imaging
The aim of this study is to evaluate the role of cardiac magnetic resonance imaging in assessment of global and regional left ventricular function and myocardial viability in patients with chronic ischemic heart disease and its impact in clinical outcome of these patients.
The study was conducted on sixty patients with chronic ischemic heart disease, reduced left ventricular ejection fraction and who had documented myocardial infarction. Patients with recent myocardial infarctions or suffering myocardial infarction during the last 6 weeks were excluded from the study.
Patients were subjected to the following;
• Thorough history taking.
• Complete physical examination with special emphasis of cardiac examination.
• Laboratory investigations.
• Cardiac examination using the following:
o Chest x-ray.
o Echocardiography for all patients.
o Dobuamine stress echocardiography for 26 patients.
o Coronary angiography
o Cardiac magnetic resonance imaging:
Cine images to assess LV function.
Late gadolinium enhanced MRI to assess myocardial viability.
The majority of patients lying within age group between 51-60 years. Fifty two patients were males (86.7%) and 8 were females (13.3%).
Of the totally examined 1020 myocardial segments, 470 segments (46.08%) showed normal motility, 355 segments (34.80%) showed hypokinesia, 163 segments (15.98%) showed akinesia and finally 32 segments (3.14%) showed dyskinesia.
Of the examined 1020 segments, 44 patients had 221 segments (21.7%) with thinned myocardium and their end diastolic wall thickness (EDWT) less than 5.5 mm, of which 205 segments (92.8%) had transmural infarction, 15 segments showed subendocardial infarction less than 50% and 1 segment had no delayed enhancement.
The results of our study indicate that an EDWT of less than 5.5 mm usually never show recovery of function after revascularization. However, even in the presence of severe wall thinning, recovery of function may occur, but only when contrast enhanced CMR excludes scar tissue
628 segments (61.57%) had no evidence of delayed enhancement, 84 segments (8.23%) had subendocardial enhancement less than or equal to 50% of the wall thickness and 308 segments (30.20%) had more than 50% of the wall thickness or transmural infarction.
The results of the present study indicate that myocardial segments with ≤50% trans-mural extension of the scar tissue are diagnosed viable and segments >50% trans-mural extension of scar tissue are diagnosed as non viable.
Delayed myocardial enhancement is not specific for myocardial infarction and can be observed in many other cardiac diseases. Unlike in ischemic heart disease, delayed enhancement in nonischemic myocardial disease generally does not correspond to particular coronary artery distribution and is often midwall rather than subendocardial or transmural. Delayed myocardial enhancement narrow the differential diagnosis of other non ischemic cardiomyopathies.
In the current study, the sensitivity and specificity of dobutamine stress echocardiography [DSE] in predicting segmental myocardial viability was 81.3% and 72.3% respectively. The disadvantage of stress echocardiography is its inability to obtain optimal imaging in all patients and it is operator dependent, both in respect of data acquisition and interpretation.
Complications of myocardial infarctions such as wall thinning, aneurysm formation, valvular regurgitation, associated pericardial effusion or left ventricular thrombus are best visualized on CMR images.
Cardiac MRI with assessment of myocardial viability can change the decision of management of the patients whether medical or surgical intervention and even in surgical intervention it could suggest whether percutaneous trans-luminal coronary angioplasty [PTCA] or coronary artery bypass grafting [CABG] is more favorable.