Novel index for invasively assessing the coronary microcirculation

Area of Science:

• Cardiovascular Research
• Interventional Cardiology
• Physiology

Background:

• Assessing coronary microcirculation independently of epicardial arteries requires a simple, invasive method.
• Current methods may lack quantitative accuracy or simplicity for widespread clinical use.

Purpose of the Study:

• To develop and validate a novel index of microcirculatory resistance (IMR).
• To assess the correlation between IMR and true microcirculatory resistance (TMR).

Main Methods:

• Utilized a coronary pressure wire and modified software to measure hyperemic mean transit time.
• Calculated IMR as distal coronary pressure divided by the inverse of hyperemic mean transit time.
• Compared IMR with TMR (distal LAD pressure divided by hyperemic flow) in Yorkshire swine.

Main Results:

• IMR and TMR significantly increased after microcirculation disruption, both with and without epicardial stenosis.
• Changes in IMR and TMR were similar and independent of epicardial artery status.
• A significant correlation was observed between IMR and TMR values and their respective percentage changes.

Conclusions:

• Measuring IMR offers a straightforward, quantitative, and invasive approach to evaluate coronary microcirculation.
• This technique may enhance the assessment of microvascular function in clinical settings.