الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
A stress myocardial perfusion scan is used to assess the blood flow to the heart muscle (myocardium) when it is stressed by exercise or medication and to determine what areas of the myocardium have decreased blood flow.
Balanced ischemia is a possible cause of false-negative myocardial perfusion SPECT studies which is the presence of diffuse coronary heart disease with homogeneous ischemia of the entire left ventricle, perfusion images of which fail to identify any single region with comparatively more reduced uptake.
The aim of our study was to investigate the causes and factors associated with false negative myocardial perfusion scans.
A 100 consecutive patients undergoing stress myocardial perfusion scan at the Nuclear Cardiology Laboratory at the cardiology department of the Main University Hospital of Alexandria were retrospectively and prospectively enrolled.
The patients had undergone myocardial perfusion scan which revealed normal and later had coronary angiography done due to persistant symptoms which revealed coronary artery disease with different locations and extents.
Patients were grouped according to normal myocardial perfusion scan with coronary artery disease and another group with normal coronary angiography.
The patients were divided into two groups:
group 1: Patients with no coronary artery disease and normal myocardial perfusion study.
group 2: Patients with coronary artery disease and normal myocardial perfusion study.
The results of the study showed that there was a male predominance among our patients with a mean age of 55 years and age range of 30-74 years.
The results also showed that there was a higher prevalence of risk factors in group 2 than group 1 especially among hypertensives and diabetics.
There was a higher prevalence of patients with reduced ejection fraction among group 2 compared with group 1 (36% and 32% respectively).
Coronary artery disease was diagnosed angiographically and the most common artery to be affected was the Left anterior descending artery (84%).
Followed by the right coronary artery with a percentage (46%), the left circumflex artery (26%) and finally the left main Artery.(4%)
The extent of lesions was also studied and showed that significant lesions in the LAD were the most common followed by borderline lesions in the LAD, followed by borderline Lesions in the RCA, finally borderline lesions in the LCX. Diseases in the left Main artery had the least incidence.
Therefore to sum up false negative myocardial perfusion scans caused by balanced ischemia phenomenon were found mostly among patients with significant lesions in the left anterior descending artery.