Abstract
BackgroundDistal coronary embolization (DCE) of thrombotic material occurs frequently during percutaneous interventions for acute myocardial infarction and can alter coronary flow grades. The significance of DCE on infarct size and myocardial function remains unsettled. The aims of this study were to evaluate the effects of DCE sufficient to cause no-reflow on infarct size, cardiac function and ventricular remodeling in a porcine acute myocardial infarction model.Methods and resultsFemale Yorkshire pigs underwent 60 min balloon occlusion of the left anterior descending coronary artery followed by reperfusion and injection of either microthrombi (prepared from autologous porcine blood) sufficient to cause no-reflow (DCE), or saline (control). Animals were sacrificed at 3 h (n = 5), 3 days (n = 20) or 6 weeks (n = 20) post-AMI. Cardiovascular magnetic resonance (CMR), serum troponin-I, and cardiac gelatinase (MMP) and survival kinase (Akt) activities were assessed. At 3d, DCE increased infarct size (CMR: 18.8 % vs. 14.5 %, p = 0.04; serum troponin-I: 13.3 vs. 6.9 ng/uL, p < 0.05) and MMP-2 activity levels (0.81 vs. 0.49, p = 0.002), with reduced activation of Akt (0.06 versus 0.26, p = 0.02). At 6 weeks, there were no differences in infarct size, ventricular volume or ejection fraction between the two groups, although infarct transmurality (70 % vs. 57 %, p< 0.04) and ventricular thinning (percent change in mid anteroseptal wall thickness:-25.6 % vs. 0.7 %, p = 0.03) were significantly increased in the DCE group.ConclusionsDCE increased early infarct size, but without affecting later infarct size, cardiac function or ventricular volumes. The significance of the later remodelling changes (ventricular thinning and transmurality) following DCE, possibly due to changes in MMP-2 activity and Akt activation, merits further study.
Highlights
Distal coronary embolization (DCE) of thrombotic material occurs frequently during percutaneous interventions for acute myocardial infarction and can alter coronary flow grades
Light microscopy imaging confirmed this range of particle size diameter (Fig. 2b). These particles were shown to have a dose-dependent effect on lowering activated clotting time (ACT) in blood samples collected separately from three animals (Fig. 2c)
Saline injection, significant differences in Thrombus Aspiration in Myocardial Infarction (TIMI) flow grade between groups were still present (p = 0.006), an improvement to either TIMI-2 or -3 was observed in 1/3 of the DCE animals, while the TIMI flow in control animals remained unchanged except in 1 case
Summary
Distal coronary embolization (DCE) of thrombotic material occurs frequently during percutaneous interventions for acute myocardial infarction and can alter coronary flow grades. In North America [8], the use of thrombus aspiration catheters as an adjunct to PCI for ST-elevation myocardial infarction is recommended. This recommendation stems from mortality benefits observed in the TAPAS trial [9]. Inconsistent effects on infarct size and mortality benefits in subsequent clinical studies have raised questions on the routine use of these devices in Primary PCI procedures for AMI [10, 11]. The role of DCE and need for therapy remain controversial
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