AUTHOR=Dai Neng , Che Wenliang , Liu Lu , Zhang Wen , Yin Guoqing , Xu Bin , Xu Yawei , Duan Shaofeng , Yu Haojun , Li Chenguang , Yao Kang , Huang Dong , Ge Junbo 

TITLE=Diagnostic Value of Angiography-Derived IMR for Coronary Microcirculation and Its Prognostic Implication After PCI

JOURNAL=Frontiers in Cardiovascular Medicine

VOLUME=Volume 8 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/cardiovascular-medicine/articles/10.3389/fcvm.2021.735743

DOI=10.3389/fcvm.2021.735743

ISSN=2297-055X

ABSTRACT=Background
Angiography derived index of microcirculatory resistance (angio-IMR) is a novel and pressure-wire-free index to assess coronary microcirculation, but its diagnostic and prognostic value remains to be elucidated.
Methods and Results
Study population consisted with 3 independent cohorts. Internal diagnostic cohort enrolled 53 patients with available hyperemic microcirculatory resistance (HMR) calculated from myocardial blood flow and pressure. External diagnostic cohort included 35 ischemia and no obstructive coronary artery disease (INOCA) patients and 45 controls. Prognostic cohort included 138 coronary artery disease (CAD) patients received PCI. Angio-IMR was calculated after estimation of angiography-derived fractional flow reserve (angio-FFR) using the equation of angio-IMR = estimated hyperemic Pa × angio-FFR× [vessel length/(K×Vdiastole)]. The primary outcome was a composite of cardiac death or readmission due to heart failure at 28 months after index procedure.
Angio-IMR demonstrated a close correlation with HMR (R=0.74, p<0.001) and its diagnostic accuracy, sensitivity, specificity and area under the curve to diagnose INOCA were 79.8%, 83.1%, 78.0% and 0.84, respectively, with a best cut-off of 25.1U. Among prognostic cohort, patients with angio-IMR≥25.1U showed significantly higher risk of cardiac death or readmission due to heart failure than those with an angio-IMR<25.1U (18.6% vs. 5.4%, adjusted HR 9.66, 95% CI 2.04-45.65, p=0.004). Angio-IMR≥25.1U was independent predictor for cardiac death or readmission due to heart failure (HR 11.15, 95% CI 1.76-70.42, p=0.010).
Conclusions
Coronary angiography-derived IMR showed a close correlation with HMR and high accuracy to predict microcirculatory dysfunction. Angio-IMR measured after PCI predicts risk of cardiac death or readmission due to heart failure in patients with CAD.