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Coronary microvascular resistance comparison of coronary arteries with and without considering vascular diameter: A
Takahiro Muroya1,2, Hiroaki Kawano3, Fumi Yamamoto2
1Division of Circulatory Sasebo City General Hospital Nagasaki Japan.
Insights
Assessing coronary microvascular resistance (MR) requires accounting for vessel diameter. Hyperemic microvascular resistance index (hMVRI) calculations vary significantly across different coronary artery sizes, impacting ischemia diagnosis.
Area of Science:
- Cardiovascular physiology
- Diagnostic imaging
- Interventional cardiology
Background:
- Coronary microvascular resistance (MR) measurement is crucial for diagnosing nonocclusive coronary artery ischemia.
- The utility of hyperemic microvascular resistance index (hMVRI), derived from average peak velocity (APV), across different coronary artery diameters remains unclear.
Purpose of the Study:
- To investigate the relationship between coronary artery diameter and hMVRI.
- To determine if hMVRI can be consistently assessed across coronary branches of varying sizes.
Main Methods:
- Thirty patients with suspected angina and nonobstructive coronary stenosis were evaluated.
- Doppler guidewire assessed velocity and pressure; quantitative coronary angiography (QCA) measured vessel diameter (DQCA).
- Coronary blood flow (CBFQCA) and hMVRIQCA were calculated during maximal hyperemia.
Main Results:
- hMVRI differed significantly between the right coronary artery and left anterior descending artery.
- No significant differences were observed in CBFQCA and hMVRIQCA between arteries.
- Correlations between CBFQCA and APV strengthened significantly when grouped by DQCA, with decreasing slopes as diameter increased.
Conclusions:
- Comparative evaluation of MR in coronary branches necessitates accounting for vessel diameter.
- Current hMVRI assessment methods may require diameter-specific adjustments for accurate interpretation.
Background And Aims:
Measurement of coronary microvascular resistance (MR) is essential for diagnosing nonocclusive coronary artery ischemia, but whether coronary branches of different diameters can be similarly assessed using hyperemic microvascular resistance index (hMVRI) calculated from average peak velocity (APV) remains unclear. We investigated the relationship between coronary arteries of different diameters and hMVRI.
Methods:
Thirty patients with suspected angina pectoris and nonobstructive coronary stenosis with fractional flow reserve >0.8 underwent evaluation of all coronary arteries using a Doppler velocity and pressure-equipped guidewire. Quantitative coronary angiography (QCA) was used to analyze vessel diameter (DQCA). Coronary blood flow (CBFQCA) was calculated as πDQCA 2/4 (0.5 × APV) and hMVRIQCA as distal coronary pressure divided by CBFQCA during maximal hyperemia.
Results:
The hMVRI was significantly higher for the right coronary artery than for the left anterior descending artery, but no significant differences between arteries were seen for CBFQCA and hMVRIQCA. Although the correlation between CBFQCA and APV was weak, CBFQCA divided into three groups according to DQCA showed very strong correlations with APV. Slopes of the straight line between APV and CBFQCA for small-, middle-, and large-diameter groups were 0.48, 0.30, and 0.21, respectively, with slope decreasing as diameter increased.
Conclusions:
Comparative evaluation of MR in coronary branches with varying vessel diameters requires vessel diameter to be accounted for.
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