Coronary circulatory indices in non-infarct related vascular territories in a porcine acute myocardial infarction model

Abstract

Abstract Background There has been debate on the reliability of fractional flow reserve (FFR) or resting pressure-derived indices in non-IRA of patients with acute ST-segment elevation myocardial infarction. Purpose This study aimed to evaluate temporal changes of coronary hemodynamic and physiologic indices in non-infarct related artery (non-IRA), which might be affected by adjacent infarcted myocardium, using an experimental animal model of acute myocardial infarction (AMI). Methods In Yorkshire swine, acute myocardial infarction was simulated with selective balloon occlusion at left circumflex artery (LCX) as IRA for 30 minutes. Non-IRA stenosis was created using bare metal stent implantation in left anterior descending artery (LAD) 4 weeks before the experiments. Serial changes of systemic hemodynamics, coronary pressure, and Doppler-derived coronary flow velocity were measured in a non-occluded LAD as non-IRA from baseline, balloon occlusion of LCX, and 15 minutes after reperfusion of LCX. Results Among the 6 experimental subjects, the median diameter stenosis of non-IRA was 33.9% (Q1-Q3: 21.7%-46.1%). During balloon occlusion of IRA, there were transient significant changes in both resting and hyperemic aortic pressure (Pa), distal coronary pressure (Pd), averaged peak velocity (APV), trans-stenotic pressure gradient (PG), and microvascular resistance of non-IRA (all P values<0.020). After reperfusion of IRA, the resting APV (P=0.002) and resting trans-stenotic PG (P=0.004) were significantly increased and resting microvascular resistance (P=0.004) was significantly decreased than those in baseline phase. However, the hyperemic APV (P=0.479), hyperemic trans-stenotic PG (P=0.778), and hyperemic microvascular resistance (P=0.816) were not significantly different compared with those in the baseline phase. After reperfusion, the FFR in non-IRA was not significantly different (0.94±0.01 vs. 0.93±0.01, P=0.353), while the CFR (1.93±0.07 vs. 1.36±0.07, P=0.025) and resting Pd/Pa (0.98±0.01 vs. 0.94±0.01, P=0.017) were significantly lower than baseline values. Conclusions In a porcine AMI model, occlusion of IRA induced significant changes of systemic hemodynamics and coronary circulatory indices of non-IRA. However, after reperfusion of IRA, FFR did not change significantly, while resting Summarizing Figure Funding Acknowledgement Type of funding source: Other. Main funding source(s): 1. Philips/Volcano, 2. Bio & Medical Technology Development Program of the National Research Foundation of the Korean government