Variability of Microcirculatory Resistance Index and Its Relationship With Fractional Flow Reserve in Patients With Intermediate Coronary Artery Lesions

Murai, Tadashi; Lee, Tetsumin; Yonetsu, Taishi; Iwai, Toshiyuki; Takagi, Takamitsu; Hishikari, Keiichi; Masuda, Ryosuke; Iesaka, Yoshito; Isobe, Mitsuaki; Kakuta, Tsunekazu

doi:10.1253/circj.cj-12-1442

Cited by 19 publications

(22 citation statements)

References 34 publications

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“…In the present study, IMR was calculated as the product of the mean distal coronary pressure during stable hyperemia and mean hyperemic transit time (Tmn) and corrected by using the following formula proposed by Yong et al19: IMR=Pa×Tmn×([1.35×Pd/Pa]–0.32). In the absence of a validated cutoff to identify abnormally increased hyperemic microvascular resistance and the reported variability of IMR in patients with or without coronary heart disease, IMR values ≥75th percentile (28.0) of the present cohort were arbitrarily assumed as high IMR 20, 21. CFR was also measured simultaneously with FFR using the thermodilution method, as described elsewhere 18.…”

Section: Methodsmentioning

confidence: 99%

“…In the absence of a validated cutoff to identify abnormally increased hyperemic microvascular resistance and the reported variability of IMR in patients with or without coronary heart disease, IMR values ≥75th percentile (28.0) of the present cohort were arbitrarily assumed as high IMR. 20,21 CFR was also measured simultaneously with FFR using the thermodilution method, as described elsewhere. 18 In this study, low CFR was defined as a value <2.0, consistent with previous studies.…”

Section: Intracoronary Physiological Indicesmentioning

confidence: 99%

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Significance of Microvascular Function in Visual—Functional Mismatch Between Invasive Coronary Angiography and Fractional Flow Reserve

Yonetsu

Murai

Kanaji

et al. 2017

JAHA

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BackgroundDespite a moderate correlation between angiographical stenosis and physiological significance, the mechanism of discordance has not been fully elucidated, particularly regarding the significance of microvascular function. This study sought to clarify whether microvascular function affects visual‐functional mismatch between quantitative coronary angiography (QCA) and fractional flow reserve (FFR).Methods and ResultsWe assessed QCA, FFR, coronary flow reserve, and the index of microcirculatory resistance in 849 non‐left‐main coronary lesions with visually estimated intermediate stenoses from 532 patients. Clinical and lesion‐specific characteristics and physiological parameters associated with mismatch and reverse mismatch were studied. Coronary flow reserve and index of microcirculatory resistance showed a weak, but significant, correlation with FFR (R=0.306, P<0.001 and R=0.158, P<0.001, respectively). Four hundred twenty‐two lesions were visually nonsignificant (diameter stenosis assessed by QCA [QCA‐DS] ≤50%) and 427 lesions were visually significant (QCA‐DS >50%). Among visually nonsignificant lesions, FFR ≤0.80 (reverse mismatch) was observed in 129 lesions (30.6%). Among visually significant lesions, FFR >0.80 (mismatch) were observed in 179 lesions (41.9%). The significant predictors of reverse mismatch were male sex, nonculprit lesions of acute coronary syndrome, left anterior descending artery location, smaller QCA reference diameter, greater QCA‐DS, lower coronary flow reserve, and lower index of microcirculatory resistance. Mismatch was associated with right coronary artery location, greater QCA reference diameter, smaller QCA‐DS, lesion length, higher coronary flow reserve, and higher index of microcirculatory resistance.ConclusionsThere was a high prevalence of visual‐functional mismatches between QCA and FFR. The discrepancy was related to clinical characteristics, lesion‐specific factors, and microvascular resistance that was undistinguishable by coronary angiography, thus suggesting the importance of physiological lesion assessment.

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Section: Methodsmentioning

confidence: 99%

Section: Intracoronary Physiological Indicesmentioning

confidence: 99%

Significance of Microvascular Function in Visual—Functional Mismatch Between Invasive Coronary Angiography and Fractional Flow Reserve

Yonetsu

Murai

Kanaji

et al. 2017

JAHA

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“…Melikian (9) and Murai et al, however, did not show a significant correlation between the IMR and FFR (9,17). Echavarria-Pinto et al (19) and our study enrolled patients with intermediate lesions in which the % diameter stenosis was 40-70% and the mean FFR was >0.8, whereas Melikian et al analyzed all atherosclerotic coronary lesions, including mild to severe stenosis and normal coronary arteries.…”

Section: Relevance Of Microvascular Integrity Associated With the Funmentioning

confidence: 50%

“…Recent studies investigating microvascular integrity estimated with IMR reported that the IMR was higher in patients with epicardial atherosclerosis than in those without; however, the IMR was not significantly correlated with the presence or absence of atheroma in that study (9). Murai et al confirmed that there was no correlation between the IMR and % diameter stenosis of intermediate de novo coronary lesions (17). Some of the patients with epicardial artery stenosis showed a lower IMR than those without epicardial artery stenosis (9,17,18).…”

Section: Microvascular Integrity In Patients With Epicardial Artery Dmentioning

confidence: 87%

“…Murai et al confirmed that there was no correlation between the IMR and % diameter stenosis of intermediate de novo coronary lesions (17). Some of the patients with epicardial artery stenosis showed a lower IMR than those without epicardial artery stenosis (9,17,18). The IMR value shows a wide distribution ranging from normal microvascular integrity to severe microvascular dysfunction and there are large gaps in the IMR even among patients with documented epicardial atherosclerosis.…”

Section: Microvascular Integrity In Patients With Epicardial Artery Dmentioning

confidence: 97%

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Epicardial Artery Stenosis with a High Index of Microcirculatory Resistance Is Frequently Functionally Insignificant as Estimated by Fractional Flow Reserve (FFR)

et al. 2016

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Objective Differences in microvascular integrity can diversely influence the functional assessment of epicardial coronary artery disease in each patient. We investigated the relevance of the index of microcirculatory resistance (IMR) and fractional flow reserve (FFR) of intermediate coronary lesions. Methods The IMR and FFR were measured in 67 intermediate coronary lesions of the left anterior descending artery of 67 patients, by using a pressure sensor/thermistor-tipped guidewire. Results To assess the differences in FFR in relationship to the IMR value, patients were divided into tertile IMR groups as follows: Low-IMR (n=22, IMR 14±3), Mid-IMR (n=23, IMR 21±2), and High-IMR (n=22, IMR 36±10). An analysis of variance showed that the High-IMR group had significantly higher FFR values (0.87±0.07) than the Low-IMR group (0.81±0.08) (p=0.03). Functionally significant lesions with FFR ! 0.8 accounted for 9% of lesions in the High-IMR group, 36% in the Low-IMR group and 22% in the Mid-IMR group (p=0.02). In the multivariate logistic analysis, the IMR value was an independent determinant of FFR ! 0.8 (p=0.03). Conclusion In patients with a high IMR, intermediate lesions as identified with visual estimation were more frequently functionally insignificant. The IMR can provide additional information in understanding the mismatch between the anatomical and functional severity of intermediate coronary stenosis.

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Coronary microvascular resistance comparison of coronary arteries with and without considering vascular diameter: A retrospective, single‐center study

Muroya,

Kawano,

Yamamoto

et al. 2023

Health Science Reports

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Background and AimsMeasurement 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.MethodsThirty 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 πDQCA2/4 (0.5 × APV) and hMVRIQCA as distal coronary pressure divided by CBFQCA during maximal hyperemia.ResultsThe 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.ConclusionsComparative evaluation of MR in coronary branches with varying vessel diameters requires vessel diameter to be accounted for.

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Variability of Microcirculatory Resistance Index and Its Relationship With Fractional Flow Reserve in Patients With Intermediate Coronary Artery Lesions

Cited by 19 publications

References 34 publications

Significance of Microvascular Function in Visual—Functional Mismatch Between Invasive Coronary Angiography and Fractional Flow Reserve

Significance of Microvascular Function in Visual—Functional Mismatch Between Invasive Coronary Angiography and Fractional Flow Reserve

Epicardial Artery Stenosis with a High Index of Microcirculatory Resistance Is Frequently Functionally Insignificant as Estimated by Fractional Flow Reserve (FFR)

Coronary microvascular resistance comparison of coronary arteries with and without considering vascular diameter: A retrospective, single‐center study

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