Coronary slow flow and angiography-derived index of microcirculatory resistance as prognostic predictors in patients with angina and normal coronary arteries: a retrospective cohort study

Abstract

Background

This study aims to investigate prognostic implications of coronary slow flow (CSF) and angiography-derived index of microcirculatory resistance (caIMR) in patients with angina and normal coronary arteries.

Methods

A total of 582 patients were enrolled with angiographically normal coronary arteries. caIMR was calculated using a commercial software. Patients were followed up for a median of 45 months. The primary endpoint was defined as major adverse cardiovascular events (MACEs) comprising death, myocardial infarction and readmission for angina or heart failure.

Results

CSF was diagnosed when TIMI grade 2 flow presented in at least one coronary artery. Multivariate analysis indicated TIMI-flow-based determination of CSF was not significantly associated with MACEs [hazard ratio (HR): 2.14; 95% confidence interval (CI): 0.87–5.31; p = 0.099), while caIMR >42 (HR: 2.53; 95% CI: 1.02–6.32; p = 0.047) were independent predictors of MACEs. Incorporation of caIMR improved the area under the curve from 0.587 to 0.642.

Conclusions

caIMR was an independent prognostic factor of long-term cardiovascular events in patients with CSF. Evaluation of caIMR improved the risk stratification of patients with angiographically-normal coronary arteries.

Keywords:

• Coronary slow flow
• index of microcirculatory resistance
• microvascular dysfunction

Acknowledgements

We thank Rainmed Ltd, Suzhou, China for providing the software and console for angiography-derived FFR and IMR.

Ethical approval and consent to participate

This study was approved by the Ethics Committee of Zhongshan Hospital, Fudan University (No.: B2016-018) and conducted in accordance with the guidelines of the Declaration of Helsinki. All participants provided written informed consent at the time of index hospitalisation.

Consent for publication

All authors are in agreement with the manuscript and consent to publish.

Authors’ contributions

All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by You Zhou, Danbo Lu and Yiqing Hu. The first draft of the manuscript was written by You Zhou and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.

Disclosure statement

There are no conflicts of interest pertaining to this submission. All authors listed meet the authorship criteria according to the latest guidelines of the International Committee of Medical Journal Editors, and all authors are in agreement with the manuscript.

Additional information

Funding

This study was supported by the National Program on Key Basic Research Project of China (Grant No: 2019YFC0840601), National Natural Science Foundation of China (Grant No: 82170338, 81970295, 81870267, 81521001 and 81670318), Shanghai Clinical Research Centre for Interventional Medicine (Grant No: 19MC1910300), Grant of Shanghai Shenkang on Key Clinical Research Project (Grant No: SHDC2020CR2015A and SHDC12019104), Grant of Shanghai Science and Technology Committee (Grant No: 20JC1410800), Key Medical and Health Projects of Xiamen City (No: 3502Z20204004), Grant of Zhongshan Hospital Affiliated to Fudan University (Grant No: 2018ZSLC01 and 2021ZSGG07).