Hamdan Medical Journal

In this paper, the most widely used and extensively validated techniques for imaging coronary artery disease are reviewed. We describe and compare the roles of echocardiography, cardiac nuclear imaging techniques and cardiac magnetic resonance imaging. For now we see through a glass, darkly. echocardiographic imaging Two-dimensional evaluation of coronary artery disease at rest Evaluation of left ventricular (LV) systolic function and wall motion at rest remains the cornerstone of diagnosis of coronary artery disease (CAD). Transthoracic echocardiography not only allows the detection of coronary territories affected after a myocardial infarction, but also visualizes the complications and functional consequences of CAD. In addition, echocardiography is the first step in the evaluation of myocardial viability and is closely correlated with prognosis. Wall motion analysis and wall motion score index Ischaemia can be visualized by echocardiography when flow-limiting stenosis or acute obstruction of a coronary artery is severe enough to disturb wall motion at rest. Both the diastolic and systolic function of the jeopardized territory are affected in acute ischaemia, even before the electrocardiographic manifestations of ischaemia become apparent. A main limitation of echocardiographic wall motion evaluation is the qualitative nature of analysis, which increases disagreement between observers. Segmental analysis of wall motion could be mapped on a 16and 17-segment model to decrease subjectivity of the test. Wall motion score index (WMSI) is a reflection of global LV contractility and is calculated by scoring individual segments of the left ventricle and then dividing the sum by 16 or 17. WMSI closely correlates with ejection fraction (EF) measured using echocardiography or other imaging modalities.1 After an acute myocardial infarction (AMI), the prognostic power of WMSI at rest is higher than that of EF.2 However, WMSI is also limited by subjectivity, because the assessment of wall motion is observer dependent. Limitations of transthoracic imaging for the evaluation of coronary artery disease Echocardiographic imaging is particularly useful when motility of the underlying CAD is sufficient to cause segmental wall motion anomaly at rest. This can be observed in patients with an acute coronary obstruction or in those with critical CAD that prohibits myocardial nourishment, even at rest. A stress modality is usually needed to evoke wall motion anomaly in patients with less severe CAD. A variety of stressors can be used, such as exercise or pharmacological agents, which are detailed below. Echocardiographic evaluation of wall motion is prone to errors because of effects such as translational motion of the heart and tethering of the infarcted area. Observation of wall thickening is less prone to such technical caveats than observation of endothelial excursion alone. In addition, the Correspondence: Gültekin Karakuş Specialist Doctor in Department of Cardiology, MD, Acibadem Maslak Hospital, Istanbul, Turkey. Email: [email protected] 5