Dipyridamole stress echo – the next step in evolution of stress imaging in the Echocardiography Laboratory at the ？akovec County Hospital

Sa？etak Introduction: Stress echocardiography is the combination of 2D echocardiography with physical, pharmacological or electrical stress. The diagnostic endpoint of the detection of myocardial ischemia is the induction of a transient change in regional function during stress.1 Myocardial ischemia results in a typical “cascade” of events in which the various markers are hierarchically ranked in a well-defined time sequence. Flow heterogeneity between subendocardial and subepicardial perfusion is the forerunner of ischemia, followed by metabolic changes, alteration in regional mechanical function, and only at a later stage by electrocardiographic (ECG) changes, global left ventricular dysfunction (LV) and pain.2 Wall motion and perfusion or coronary flow reserve (CFR) changes are highly accurate, and more accurate than ECG changes for detection and location of underlying coronary artery disease. However, wall motion is more specific and requires ischemia; perfusion changes are more sensitive and may occur in the absence of true ischemia (microvascular disease, or LV hypertrophy).1 The three most common ischemic stressor are exercise, dobutamine, and vasodilators (dipyridamole, adenosine). They are equally potent for inducing wall abnormalities in the presence of a critical epicardial coronary artery stenosis. Dobutamine and exercise manly act through increased myocardial oxygen demand. Vasodilators act by stimulating A2 adenosinergic receptors present on the endothelial and smooth muscle cells of coronary arterioles and induce ischemia due to reduced subendocardial flow supply subsequent to inappropriate arteriolar vasodilatation and steal phenomena.1 Dipyridamole was the first pharmacological stress agent used for the diagnosis of coronary artery disease, with a pioneering indication proposed in Europe for the identification of ischemia during 12-lead ECG3, and later in the USA by Lance Gould as hyperemic stress perfusion imaging.4 Dipyridamole stress echocardiography pioneered in the year of 1985 (Picano et al). The safety record of high dose dipyridamole is well established on the basis of large scale multicentric studies with data from thousands of patients. The incidence of major complications, i.e. myocardial infarction, atrioventricular block, cardiac asystole, sustained ventricular tachycardia, is about 1/1500 cases. The mortality rate is about 1/10000 cases, similar to that of the exercise stress test. Dipyridamole has a better safety profile than when stress testing with dobutamine, where the incidence of major adverse reactions is about