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Microvascular resistance reserve before and after PCI: A serial FFR and [15O] H2O PET study
Masahiro Hoshino1, Ruurt A Jukema2, Nico Pijls3
1Departments of Cardiology, Amsterdam UMC, Vrije Universiteit Amsterdam De Boelelaan 1117, 1081 HV Amsterdam, the Netherlands; Department of Cardiology, Tsuchiura Kyodo General Hospital, Japan.
Background And Aims:
Microvascular Resistance Reserve (MRR) has recently been introduced as a microvasculature-specific index and hypothesized to be independent of coronary stenosis. The aim of this study was to investigate the change of MRR after percutaneous coronary intervention (PCI).
Methods:
In this post-hoc analysis from the PACIFC trials, symptomatic patients underwent [15O]H2O positron emission tomography (PET) and invasive fractional flow reserve (FFR) before and after revascularization. Coronary flow reserve (CFR) from PET and invasive FFR were used to calculate MRR.
Results:
Among 52 patients (87 % male, age 59.4 ± 9.4 years), 61 vessels with a median FFR of 0.71 (95 % confidence interval: 0.55 to 0.74) and a mean MRR of 3.80 ± 1.23 were included. Following PCI, FFR, hyperemic myocardial blood flow (hMBF) and CFR increased significantly (all p-values ≤0.001). MRR remained unchanged after PCI (3.80 ± 1.23 before PCI versus 3.60 ± 0.97 after PCI; p=0.23). In vessels with a pre-PCI, FFR ≤0.70 pre- and post-PCI MRR were 3.90 ± 1.30 and 3.73 ± 1.14 (p=0.56), respectively. Similar findings were observed for vessels with a FFR between 0.71 and 0.80 (pre-PCI MRR 3.70 ± 1.17 vs. post PCI MRR 3.48 ± 0.76, p=0.19).
Conclusions:
Our study indicates that MRR, assessed using a hybrid approach of PET and invasive FFR, is independent of the severity of epicardial stenosis. These findings suggest that MRR is a microvasculature-specific parameter.
Insights
Microvascular Resistance Reserve (MRR) is a microvasculature-specific index. This study found MRR remains unchanged after percutaneous coronary intervention (PCI), supporting its independence from epicardial stenosis severity.
Area of Science:
- Cardiology
- Medical Imaging
- Physiology
Background:
- Microvascular Resistance Reserve (MRR) is a novel index assessing microvasculature function.
- MRR is hypothesized to be independent of epicardial coronary stenosis.
- Understanding MRR's behavior post-intervention is crucial.
Purpose of the Study:
- To investigate the changes in Microvascular Resistance Reserve (MRR) after percutaneous coronary intervention (PCI).
- To evaluate if MRR is influenced by epicardial stenosis severity post-revascularization.
Main Methods:
- Post-hoc analysis of the PACIFC trials involving symptomatic patients.
- Utilized [15O]H2O positron emission tomography (PET) and invasive fractional flow reserve (FFR) measurements before and after PCI.
- Calculated MRR using PET-derived Coronary Flow Reserve (CFR) and invasive FFR.
Main Results:
- Included 52 patients and 61 vessels; median pre-PCI FFR was 0.71.
- Following PCI, FFR, hyperemic myocardial blood flow (hMBF), and CFR significantly increased (p ≤0.001).
- MRR showed no significant change after PCI (3.80 ± 1.23 pre-PCI vs. 3.60 ± 0.97 post-PCI; p=0.23), irrespective of pre-PCI FFR values.
Conclusions:
- MRR, assessed via a hybrid PET and invasive FFR approach, is independent of epicardial stenosis severity.
- These findings support MRR as a specific microvasculature parameter.
- MRR remains stable after PCI, indicating preserved microvascular function unrelated to epicardial intervention outcomes.
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