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Early prediction of infarct size by quantitative myocardial blush grade in patients with acute non-st-elevation and ST-elevation myocardial infarction treated with primary angioplasty and stent placement
© Riedle et al; licensee BioMed Central Ltd. 2009
- Published: 28 January 2009
- Infarct Size
- Stent Placement
- Microvascular Obstruction
- Primary Angioplasty
- Artery Blood Flow
The widespread use of percutaneous coronary interventions has resulted in a significant improvement of clinical outcomes in patients both with ST-elevation and in non-ST-elevation myocardial infarction (STEMI and NSTEMI). The restoration of epicardial artery blood flow in the revascularized coronary artery however, may not necessarily guarantee preserved microvascular integrity in the downstream myocardium. Because the latter is a principal predictor of clinical outcomes, methods that can provide objective assessment of infarct size early in acute infarction may be of great potential clinical utility.
To determine whether quantification of myocardial blush grade (MBG) can aid the determination of infarct size during cardiac catheterization in patients with acute myocardial infarction.
We prospectively examined patients with first STEMI (n = 45) and NSTEMI (n = 50), all treated with primary angioplasty and stent placement. ECG-gated angiographic series were used to quantify MBG, by placing regions of interest (ROI) in the infarct related coronary territory, in order to estimate the time course of blush intensity rise. Gmax was defined as the peak grey level intensity and Tmax as the time to peak intensity rise. By this approach, we anticipated that an adequate and prompt filling of myocardial capillaries with contrast agent (high Gmax within a short Tmax) would be indicative of preserved microvascular integrity and predictive of small infarct size and vice versa. Assessment of myocardial scar, determined by contrast-enhanced magnetic resonance imaging (MRI), 2 to 4 days after infarction, deemed as the standard reference for estimation of infarct size. Briefly, 10 minutes after 0.2 mmol/kg body weight gadolinium contrast injection, 2 volume stacks of inversion-recovery gradient-echo images covering the whole left ventricle were generated. Infarct size was calculated as the amount of hyperenhanced myocardium related to the total LV-mass. Infarct transmurality was assessed visually based on a 5-grade scale (i.e. 1 = 0–25%, 2 = 25–50%, 3 = 50–75%, 4/5 = 75–100% transmurality without/with microvascular obstruction).
Quantitative MBG is a valuable predictor of the total extent of myocardial infarction and infarct transmurality. This information can be easily acquired during clinically indicated cardiac catheterization, immediately after myocardial reperfusion, and can be utilized for tailoring appropriate pharmacological interventions and to support the early risk stratification of patients with acute ischemic syndromes.
This article is published under license to BioMed Central Ltd.