Noninvasive Prediction of Ultimate Infarct Size at the Time of Acute Coronary Occlusion Based on the Extent and Magnitude of Collateral-Derived Myocardial Blood Flow

Abstract

Background We hypothesized that by detecting regions with adequate collateral-derived myocardial blood flow (MBF) within the risk area (RA), we could predict ultimate infarct size (IS) at the time of coronary occlusion. Methods and Results Group 1 dogs (n=15) underwent coronary occlusion without reperfusion, whereas group 2 dogs (n=6) underwent both occlusion and reperfusion. RA was measured with aortic root injections of microbubbles. Myocardial contrast echocardiography (MCE) was performed with high mechanical index intermittent harmonic imaging at pulsing intervals (PIs) of <1 to 30 cardiac cycles during an intravenous infusion of microbubbles (Sonozoid). MBF was measured with radiolabeled microspheres, and postmortem tissue staining was used to determine IS. Perfusion defect size (PDS) on MCE varied with the PI and was largest at a PI of 2.6±0.4 seconds, where it correlated well with RA ( r =0.82). PDS was smallest at a PI of ≥10.6±1.5 seconds, where it correlated closely with IS ( r ≥0.92). Areas that underwent necrosis could be identified early after coronary occlusion as having the lowest microvascular flow velocity (β) and MCE-derived MBF (A×β). The results were similar with or without reperfusion. Because of variability in collateral-derived MBF, there was no correlation between RA and ultimate IS ( P =0.37). The extent of regional dysfunction also correlated poorly with IS ( r =0.31). Conclusions MCE can be used immediately after coronary occlusion to define ultimate IS by measuring the magnitude and spatial extent of collateral-derived residual MBF within the RA. Thus, it could help individualize risk and management in acute myocardial infarction.

Myocardial Contrast Echocardiography

“…12,13 MCE can also be used to define the extent of collateral perfusion during coronary occlusion and hence to predict the ultimate infarct size (provided mechanical intervention does not increase the infarct size from microembolism of atherosclerotic debris or from reperfusion injury). 14 The extent of collateral perfusion during coronary occlusion has been shown to correlate with the extent of viable myocardium. 15 The case discussed below illustrates an example of a patient with AMI who had extensive collateral flow.…”

Segmental quantitative analysis of myocardial contrast echocardiography images using a bullseye representation

“…Considering the ability of MCE for assessing microvascular integrity, this technique may be useful for quantifying myocardial viability after sucessful reperfusion in acute myocardial infarction [1] and to estimate infarct size [2]. To quantitatively analyse the different patterns of myocardial opacification following coronary occlusion and reperfusion, in this study, we propose a method that is able to aggregate information from myocardial contrast images and tissue characterization analyzes to compose a my ocardial perfus ion and texture polar map of the left ventricle in an animal model of myocardial infarction.…”

Contrast echocardiography accurately predicts myocardial perfusion before angiography during acute myocardial infarction

“…MCE can be used to reliably assess myocardial reperfusion following primary percutaneous coronary intervention (PCI) for AMI and to predict improvement in left ventricular (LV) function, as well as to assess the degree of collateral support to the infarcted territory (6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17) OBJECTIVES: To determine whether myocardial contrast echocardiography (MCE) can quickly and accurately assess myocardial perfusion and infarct-related artery (IRA) patency before emergency angiography during acute myocardial infarction (AMI). BACKGROUND: Despite encouraging experimental and clinical studies, the reliability and practicality of MCE in predicting IRA patency during AMI before angiography has not been proven.…”

“…Thus, despite promising human and animal studies (14,(18)(19)(20)(21)(22), it remains to be shown whether the technique is practical and accurate in the clinical setting.…”