<h2 class="section-title">Abstract</h2> <div id="as0005"> <h3 id="st0010">Background</h3> <p id="sp0065">In this prospective study, we compared the invasive measures of microvascular function in two subsets: patients with pharmacoinvasive <a href="https://www.sciencedirect.com/topics/medicine-and-dentistry/blood-clot-lysis" title="Learn more about Blood Clot Lysis">thrombolysis</a> for STEMI, and patients undergoing <a href="https://www.sciencedirect.com/topics/medicine-and-dentistry/percutaneous-coronary-intervention" title="Learn more about Percutaneous Coronary Intervention">percutaneous coronary intervention</a> (PCI) for <a href="https://www.sciencedirect.com/topics/medicine-and-dentistry/non-st-segment-elevation-myocardial-infarction" title="Learn more about Non ST Segment Elevation Myocardial Infarction">NSTEMI</a>.</p> </div> <div id="as0010"> <h3 id="st0015">Methods</h3> <p id="sp0070">The study consisted of 17 patients with STEMI referred for <a href="https://www.sciencedirect.com/topics/medicine-and-dentistry/cardiac-catheterization" title="Learn more about Cardiac Catheterization">cardiac catheterisation</a> post thrombolysis, and 20 patients with NSTEMI. Coronary physiological indexes were measured in each patient before and after PCI.</p> </div> <div id="as0015"> <h3 id="st0020">Results</h3> <p id="sp0075">The median pre-PCI index of microcirculatory function (IMR) at baseline was significantly higher in the STEMI group than the NSTEMI group (26 units vs. 15 units, <em>p</em> = 0.02). Following PCI, IMR decreased in both groups (STEMI 20 units vs. NSTEMI 14 units, <em>p</em> = 0.10). There was an inverse correlation between post PCI IMR and <a href="https://www.sciencedirect.com/topics/medicine-and-dentistry/heart-left-ventricle-ejection-fraction" title="Learn more about Heart Left Ventricle Ejection Fraction">left ventricular ejection fraction</a> (LVEF) (<em>r</em> = −0.52, <em>p</em> = 0.001). Furthermore, post PCI IMR was an independent predictor of index admission LVEF in the total population (<em>β</em> = −0.388, <em>p</em> = 0.02).</p> </div> <div id="as0020"> <h3 id="st0025">Conclusion</h3> <p id="sp0080">Invasive measures of microvascular function are inferior in a pharmacoinvasive STEMI group compared to a clinically stable NSTEMI group. In the STEMI population, the IMR following coronary intervention appears to predict LVEF.</p> </div>