Angiography-based Coronary Microvascular Assessment with and without Intracoronary Pressure Measurements ─ a Systematic Review

Abstract Background: In recent years, several indices have been proposed for quantifying coronary microvascular resistance. Objective: The objective of this study was to identify and analyze angiography-derived indices of microvascular resistance that have been validated against an invasive reference method. We aimed compare of these methods regarding their limits of agreement with their reference methods and exploring their advantages and inherent limitations. Methods and results: We searched PubMed from inception until 2022 for studies on different techniques for quantifying microvascular resistance. Seven studies met the inclusion criteria. Five studies included techniques that applied calculations based solely on invasive angiography (angiography-based methods), and were validated against invasively measured thermodilution-derived index of microvascular resistance (invasive IMR). The remaining two studies combined angiography with invasively measured intracoronary pressure data (combined angio- and pressure-based methods), and were validated against invasive Doppler Measurements. We converted the ± 1.96 standard deviation limits of agreement with the reference method from the seven studies into percentages relative to the cut-off value of the reference method. This conversion was performed to enhance the interpretability of the results. The lower limits of agreement for angiography-based methods ranged from − 122% to -60%, while the upper limits ranged from 74–135%. The range of the limits of agreement was considerably lower for the two combined angiography- and pressure-based methods, standing at -52–60% and − 25–27%. Conclusion: Our findings suggest that combined angiography- and pressure-based methods provide a more reliable assessment of microvascular resistance compared to methods relying solely on angiography.