Summarized Coronary Artery Caliber and Left Ventricle Mass for Scoring of Cardiac Ischemia: Diagnostic and Prognostic Value

1.1 Importance of methods for scoring coronary angiograms to reflect extent and severity of CAD Despite advances in modern medicine, the early detection of patients with obstructive coronary lesions remains an unresolved problem due to frequently occurring atypical, painless, and asymptomatic clinical variants of ischemic heart disease. For example, 80 to 90% of sudden cardiac deaths occur with a background of significant coronary artery disease (Zipes, 1998) and sudden death is often the first presentation of the cardiac disease. It is estimated that sudden death occurs in 33% to 70% of cardiac disease patients (Davies, 2000). In addition, an acute myocardial infarction (MI) usually develops in patients with multi-vessel coronary disease (Goldstein et al., 2000), while angiographic studies have shown that an acute MI may develop in coronary segments having only slight or moderate stenosis. It is well known that a ruptured atheromatous plaque in the coronary artery can initiate intracoronary thrombosis and occlusion with the subsequent development of an acute MI. However, plaque rupture with platelet activation and thrombus formation are more recognized as the key events in the pathogenesis of acute coronary syndrome than are the extent and severity of the coronary artery disease (CAD). Additionally, the symptoms of myocardial ischemia may not be caused by obstructive lesions in the coronary arteries at all. Myocardial ischemia may occur not only due to decreased blood flow through epicardial coronary arteries, but also because of the increased oxygen demand in patients with myocardial hypertrophy or hyperfunction. Myocardial hypertrophy may be the cause of cardiac arrhythmias due to coronary insufficiency in hypertensive patients. However, even in the absence of obstructive CAD, hypertensive patients frequently have angina or may show electrocardiographic abnormalities suggestive of myocardial ischemia due to coronary insufficiency (Vogt et al., 1992). In this era of great achievements in cardiology, we are still in need of a convenient and informative coronary arteries analysis system that would allow us to quantitatively estimate the size and severity of atherosclerotic CAD and myocardial ischemia burden.