Quantitative Flow Ratio-Derived Index of Microcirculatory Resistance as a Novel Tool to Identify Microcirculatory...

Area of Science:

• Cardiology
• Medical Imaging
• Diagnostic Technologies

Background:

• Coronary microvascular disease (CMVD) is linked to poor cardiovascular outcomes.
• Current diagnostic methods for CMVD, like invasive pressure wire measurement of the index of microcirculatory resistance (IMR), have practical limitations.
• There is a need for reliable, noninvasive quantitative diagnostic tools for CMVD.

Purpose of the Study:

• To evaluate the diagnostic efficiency of the quantitative flow ratio-derived index of microcirculatory resistance (QMR) in predicting CMVD.
• To compare QMR with invasive IMR measurements in patients with symptoms of ischemia and no obstructive coronary artery disease (INOCA).

Main Methods:

• Retrospective assessment of QMR diagnostic efficiency in 103 coronary vessels from 66 patients.
• Comparison of QMR with invasive IMR measurements obtained via thermodilution technique.
• Receiver Operating Characteristic (ROC) curve analysis to determine diagnostic performance.

Main Results:

• The study included 66 patients, with 62.1% diagnosed with CMVD.
• QMR demonstrated good diagnostic performance for predicting microcirculatory function across all assessed arteries (AUC = 0.820, p < 0.001).
• Optimal QMR cut-off of 266 achieved 82.9% sensitivity, 72.6% specificity, and 76.7% diagnostic accuracy.

Conclusions:

• QMR is a potentially valuable tool for assessing coronary microcirculation.
• This noninvasive method may allow for quicker, easier, and more economical evaluation of coronary microvascular function.
• QMR could overcome the limitations associated with invasive pressure wire-based IMR measurements.