Abstract
Abstract Aims The study of coronary microcirculation has gained increasing consideration and importance in cath-lab. Despite the increase of evidence its use still remains very limited. QFR is a novel angio-based approach for the evaluation of coronary stenosis. The aim of our study was to use the QFR assessment in stable patients to recreate the IMR formula and to correlate the result of the two techniques. Methods and results From 1 June 2019 to 29 February 2019, 200 patients with CCS and indication of coronary artery angiography and referred to the cath-lab of the University Hospital of Ferrara (Italy) were enrolled. After baseline coronary angiogram, quantitative flow ratio, fractional flow reserve and index of microcirculatory resistance evaluation were performed. Pearson correlation (r) between Angio-based index of microcirculatory resistance (A-IMR) and IMR 0.32 with R2 = 0.098, P = 0.03: McNemar test showed a difference between the two test of 6.82% with 95% CI from −12.05% to 22.89%, which is not significant (P = 0.60). Bland and Altman plot showed a mean difference of 23.3 (from −26.5 to 73.1). Sensitivity, specificity, NPV and PPV were 70%, 83.3%, 75% and 70% for A-IMR value > 44.2. The area under the ROC curve for A-IMR was 0.76 (95% CI: 0.61–0.88, P = 0.0003). Conclusions We have validated for the first time the formula of the A-IMR, a tool for the calculation of microvascular resistance which does not require the use of pressure guides and the induction of hyperemia
Highlights
Over the years, the study of coronary microcirculation has gained increasing consideration and importance in cath lab, both in stable and unstable patients [1, 2]
Exclusion criteria were (i) left main coronary artery diseases; (ii) multivessel diseases; (iii) extremely tortuous or calcified coronary artery; (iv) previous coronary artery bypass graft (CABG); (v) atrial fibrillation; and (vi) adenosine intolerance. e study was conducted in accordance with the ethical principles of the Declaration of Helsinki, and the protocol was approved by the institutional review board, and all patients provided written informed consent
From June 1, 2019, to February 29, 2019, 200 patients with Chronic coronary syndrome COPD (CCS) and indication of coronary artery angiography were referred to the cath lab
Summary
The study of coronary microcirculation has gained increasing consideration and importance in cath lab, both in stable and unstable patients [1, 2]. Despite the increase of evidence in favour of the study of coronary microvascular resistance (for example, with IMR), its use still remains very limited. E main factors that have limited its use are essentially (1) the induction of maximal hyperemia by adenosine in a critical patient setting such as that with STEMI, (2) the use of guides in patients without coronary stenosis, and (3) the increase in the procedural time. QFR has shown good agreement with pressure wiredetermined FFR measurements in patients with stable coronary artery disease [3]. QFR has shown good agreement with pressure wiredetermined FFR measurements in patients with stable coronary artery disease [3]. e aim of our study was to use the QFR assessment in stable patients to recreate the IMR formula and to correlate the result of the two techniques
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