Related Experiment Video
Updated: Aug 25, 2026
Non-invasive Assessment of Microvascular and Endothelial Function
Published on: January 29, 2013
Influence of microvascular resistance on fractional flow reserve after successful percutaneous coronary intervention
Tadashi Murai1, Tetsumin Lee, Taishi Yonetsu
1Department of Cardiology, Tsuchiura Kyodo General Hospital, Tsuchiura, Japan.
Objectives And Background:
Increased microvascular resistance may impair hyperemic coronary flow by limiting the maximal and constant vasodilation, resulting in increased fractional flow reserve (FFR) due to the underestimation of the translesional pressure gradient. We examined whether microvascular resistance affects FFR after successful percutaneous coronary intervention (PCI).
Methods And Results:
We measured FFR and the index of microcirculatory resistance (IMR) in 104 coronary arteries of 98 patients after successful elective stenting. FFR values were compared according to the quartiles of the IMR values. Coronary flow was assessed using the hyperemic mean transit time (Tmn ). The IMR values for the interquartile ranges of 8.5-11.3, 13.9-16.3, 20.9-24.5, and 34.2-61.6 were 10.2, 15.1, 22.8, and 38.2, respectively. Both FFR and Tmn values differed significantly across the IMR quartiles (P < 0.001). The angiographic and intravascular ultrasound findings and post-PCI cardiac troponin levels showed no significant difference across the IMR quartiles. Multivariate logistic regression analysis revealed that the left anterior descending artery lesion location (odds ratio [OR] 0.17, 95% confidence interval [CI] 0.06-0.49, P = 0.001), IMR (OR 1.05, 95% CI 1.01-1.09, P = 0.012), and minimal cross-sectional lumen area (OR 1.49, 95% CI 1.03-2.17, P = 0.036) were independent predictors of increased FFR.
Conclusions:
Increased microvascular resistance may reduce coronary flow and increase FFR after successful elective PCI.
Insights
High microvascular resistance can falsely elevate fractional flow reserve (FFR) after coronary stenting. This study shows increased index of microcirculatory resistance (IMR) is linked to higher FFR, impacting assessment of intervention success.
Area of Science:
- Cardiovascular Medicine
- Interventional Cardiology
- Physiology
Background:
- Increased microvascular resistance may impair hyperemic coronary flow.
- This can lead to underestimation of the translesional pressure gradient, potentially affecting fractional flow reserve (FFR) measurements.
- The impact of microvascular resistance on FFR after percutaneous coronary intervention (PCI) requires further investigation.
Purpose of the Study:
- To examine the effect of microvascular resistance on FFR following successful PCI.
- To determine if elevated microvascular resistance influences FFR values in patients who have undergone elective stenting.
Main Methods:
- FFR and index of microcirculatory resistance (IMR) were measured in 104 coronary arteries from 98 patients post-PCI.
- Patients were stratified into quartiles based on IMR values.
- Coronary flow was assessed using hyperemic mean transit time (Tmn).
Main Results:
- Significant differences in FFR and Tmn were observed across IMR quartiles (P < 0.001).
- Multivariate analysis identified left anterior descending artery location, IMR, and minimal lumen area as independent predictors of increased FFR.
- No significant differences were found in angiographic, intravascular ultrasound, or troponin levels across IMR quartiles.
Conclusions:
- Elevated microvascular resistance is associated with reduced coronary flow.
- Increased microvascular resistance may lead to an overestimation of FFR after successful elective PCI.
- IMR is an independent predictor of increased FFR post-PCI.
