Arch Hellen Med, 17(4), July-August 2000, 358-365
Exercise testing with myocardial perfusion imaging
as a tool for diagnosis of coronary artery disease
and risk stratification for major cardiac events
E.I. RENTOUKAS, G.A. LAZAROS
Department of Cardiology, General Hospital of Athens “G. Genimatas”, Athens, Greece
Exercise testing with myocardial perfusion imaging constitutes an accurate tool for the diagnosis of coronary heart disease which has been in use for more than two decades. The regional distribution of myocardial perfusion can be visualized using radiopharmaceuticals which accumulate in proportion to the myocardial blood flow. A normal scintigraphic imaging shows a homogeneous uptake of the radiopharmaceutical throughout the myocardium, and the term defect is applied to a localized myocardial area with a relative decrease in radiotracer uptake. A defect present on the initial stress images but no longer present, or present to a lesser degree, on the resting images indicates myocardial ischemia. A defect unchanged on exercise and rest images indicates infarction and scar tissue. The contribution of myocardial perfusion imaging to the diagnosis of myocardial ischemia stems from its ability to detect inhomogeneities of perfusion arising from hemodynamically significant coronary stenoses with a sensitivity and specificity of 91% and 89% respectively. The higher sensitivity of myocardial perfusion imaging in comparison to simple exercise stress testing is due mainly to the possibility of quantitative analysis that myocardial perfusion imaging allows, leading to a lesser degree of interobserver variability. In addition, an independent relationship has been established between myocardial perfusion and prognosis (i.e. risk stratification) in a variety of clinical settings. Myocardial perfusion imaging thus constitutes a cost-effective method for identifying patients at high risk for major cardiac events (cardiac death, myocardial infarction and unstable angina).
Key words: Coronary heart disease, Myocardial perfusion imaging, Risk stratification.