Coronary and Myocardial Angiography

Abstract

A ngiographic assessment of epicardial coronary artery blood flow has played a pivotal role in our understanding of the "time-dependent open artery hypothesis" and in the evaluation of reperfusion strategies over the past 2 decades. [1][2][3][4][5][6][7][8] It has become increasingly apparent, however, that clinical outcomes are not only associated with angiographic flow in the epicardial artery, but also with angiographic flow in the myocardium. 9 -13 To this end, the goal of reperfusion therapies has shifted to include reperfusion downstream at the level of capillary bed, and it might be more appropriate that the hypothesis now be termed "the time dependent open artery and open microvascular hypothesis." The goal of this article is to review angiographic methods used to evaluate myocardial ischemia and infarction and to discuss the insights into the pathophysiology of acute coronary syndromes provided by these angiographic indexes of coronary artery blood flow and myocardial perfusion.

Importance of Tissue Perfusion in ST Segment Elevation Myocardial Infarction Patients Undergoing Reperfusion Strategies: Role of Adenosine

“…Normal tissue perfusion (TMG 2-3) measured 2 weeks after thrombolysis or stenting is associated with a significant decrease in infarct size and a higher salvage index as measured by SPECT. 1 Similarly, the presence of microvascular obstruction on MRI is associated with significantly larger infarcts. 2 Infarct size reduction would be expected to result in preservation of ventricular function, and this is supported by numerous studies showing improved function in the presence of preserved tissue perfusion.…”

“…On the other hand, myocardial blush grade (MBG) is a semiquantitative angiographic measurement of evaluating tissue perfusion, and clinicians nowadays frequently use this method. 1 Other more recently developed diagnostic modalities include myocardial contrast echocardiography (MCE), MRI and vasodilatory flow reserve utilizing a Doppler flow wire, and a close correlation exists between these various methods and MBG.…”

“…Numerous studies note a marked disparity between epicardial blood flow and tissue perfusion, emphasizing that normalization of epicardial flow (TIMI Grade 3) frequently does not result in adequate tissue perfusion (MBG 2 or 3). 1 For example, the CADILLAC study shows that normal tissue perfusion is observed only in ∼ 17% of patients with TIMI 3 flow. 2 Studies also demonstrate that tissue perfusion is an independent, multivariate predictor of both early and late mortality in patients with STEMI undergoing thrombolysis or percutaneous coronary intervention (PCI).…”

“…Patients who achieve TIMI 3 flow after thrombolysis exhibit a sevenfold increase in mortality at 30 days if tissue perfusion is abnormal (MBG 0/1), and this increased risk is maintained for up to 2 years. 1 Tissue perfusion is also an independent predictor of mortality in STEMI patients undergoing PTCA and stenting. 3 Similarly, abnormal tissue perfusion in NSTEMI patients undergoing PCI is also associated with a higher risk of myocardial necrosis and death at 6 months and 1 year.…”

“…1 Experimental models document convincingly the concept of progressive microcirculatory failure (often referred to as the "no-reflow" phenomenon) and "no-reflow" appears to be an important component of the potential deleterious effects of reperfusion; so called myocardial reperfusion injury. 2 In animal models, abnormalities of tissue perfusion are associated with an increase in infarct size and, conversely, agents that preserve microvascular flow result in a significant reduction in irreversible myocyte necrosis.…”