Angiography-derived versus invasively-determined index of microcirculatory resistance in the assessment of coronary microcirculation: A systematic review and meta-analysis

Background The index of microvascular resistance (IMR) is an established tool to assess the status of coronary microcirculation. However, the need for a pressure wire and hyperemic agents have limited its routine use and have led to the development of angiography-derived pressure-wire-free methods (angiography-derived IMR [IMRAngio]). In this review and meta-analysis, we aim to assess the global diagnosis accuracy of IMRAngio versus IMR. Methods A systematic review of the literature was performed. Studies directly evaluating IMRAngio versus IMR were considered eligible. Pooled values of diagnostic test and summary receiver operator curve were calculated. Results Seven studies directly comparing IMRAngio versus IMR were included (687 patients; 807 vessels). Pooled sensitivity, specificity, +likelihood ratio (LR), and -LR were 82%, 83%, 4.5, and 0.26 respectively. Pooled accuracy was 83% while pooled positive predictive value and negative predictive value were 76% and 85%, respectively. Comparable results were obtained when analyzing by clinical scenario (acute and nonacute coronary syndromes). Conclusion IMRAngio shows a good diagnostic performance for the prediction of abnormal IMR.