Contrast Echocardiography in Coronary Artery Disease

Abstract

Conventional echocardiography is widely used and well documented in evaluation of patients with stable and unstable coronary artery disease (Mollema et al., 2009). In particular, assessment of left ventricular function, volumes and ejection fraction adds important prognostic information in individual patients. In addition, echocardiography may detect any concomitant valvular heart disease as well as acute complications in unstable coronary syndromes. Stress echocardiography has through several studies established its role in diagnosis of stable coronary artery disease and assessment of myocardial viability (Sicari et al., 2008). However, introduction of ultrasound contrast agents and contrast specific imaging modalities have significantly improved the usefulness of echocardiography in diagnosis and assessment of coronary artery disease (Dijkmans et al., 2006). Indications for use of ultrasound contrast are implemented in guidelines for assessment of left ventricular function at rest and during stress echocardiography (Senior et al., 2009; Mulvagh et al., 2008). Ultrasound contrast is recommended for assessing left ventricular ejection fraction at rest when image quality is suboptimal and for stress echocardiography when the endocardial boarder is not visualized in 2 or more left ventricular segments (Senior et al., 2009; Mulvagh et al., 2008). In contrast echocardiography regional myocardial function and perfusion may be assessed simultaneously, thereby optimizing the non-invasive diagnostics of coronary artery disease. The incremental value of assessing myocardial perfusion in diagnosing coronary artery disease is emphasised by the ischemic cascade (Fig. 1), demonstrating that hypoperfusion precedes functional impairment, ECG changes, symptoms and myocardial necrosis as depicted in Fig.1. (Crossman, 2004; Leong-Poi et al., 2002). Diagnosing distribution and extent of myocardial ischemia by contrast echocardiography can give information on the total ischemic burden and has become a supplemental tool in evaluation of the physiological impact of an angiographic coronary artery stenosis. Consequently, myocardial perfusion assessment by contrast echocardiography may also be used for risk prediction in patients with known coronary artery disease and in prioritizing the need for urgent revascularization among patients with acute coronary syndromes (Jeetley et al., 2007; Rinkevich et al., 2005; Lonnebakken et al., 2011). It has the potential to become a future tool to tailor and evaluate the effect of treatment on myocardial perfusion in patients with different clinical syndromes of coronary artery disease. Furthermore,