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Immediate assessment of coronary microcirculation during treatment of ST elevation myocardial infarction (STEMI) may facilitate patient stratification for targeted treatment algorithms. Use of pressure-wire to measure the index of microcirculatory resistance (IMR) is possible but has inevitable practical restrictions. We aimed to develop and validate angiography-derived index of microcirculatory resistance (IMRangio) as a novel and pressure-wire-free index to facilitate assessment of the coronary microcirculation. 45 STEMI patients treated with primary percutaneous coronary intervention (pPCI) were enrolled. Immediately before stenting and at completion of pPCI, IMR was measured within the infarct related artery (IRA). At the same time points, 2 angiographic views were acquired during hyperaemia to measure quantitative flow ratio (QFR) from which IMRangio was derived. In a subset of 15 patients both IMR and IMRangio were also measured in the non-IRA. Patients underwent cardiovascular magnetic resonance imaging (CMR) at 48 h for assessment of microvascular obstruction (MVO). IMRangio and IMR were significantly correlated (ρ: 0.85, p  1.55% of left ventricular mass) (p = 0.03 and p = 0.005, respectively). Post-pPCI IMRangio presented and area under the curve (AUC) of 0.96 (CI95% 0.92-1.00, p  40U and of 0.81 (CI95% 0.65-0.97, p  1.55%. IMRangio is a promising tool for the assessment of coronary microcirculation. Assessment of IMR without the use of a pressure-wire may enable more rapid, convenient and cost-effective assessment of coronary microvascular function.

Original publication




Journal article


Int J Cardiovasc Imaging

Publication Date





1395 - 1406


Index of microcirculatory resistance, Microvascular dysfunction, Microvascular obstruction, Quantitative flow ratio, STEMI, Aged, Angioplasty, Balloon, Coronary, Blood Flow Velocity, Cardiac Catheterization, Cardiac Catheters, Coronary Angiography, Coronary Artery Disease, Coronary Circulation, Coronary Vessels, Female, Humans, Magnetic Resonance Imaging, Male, Microcirculation, Middle Aged, Predictive Value of Tests, Prospective Studies, Radiographic Image Interpretation, Computer-Assisted, Reproducibility of Results, ST Elevation Myocardial Infarction, Stents, Transducers, Pressure, Vascular Resistance