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Evaluation of Coronary Flow Reserve After Myocardial Ischemia Reperfusion in Rats
Published on: June 28, 2019
Effect of distal embolization on myocardial perfusion reserve after percutaneous coronary intervention: a
Joseph B Selvanayagam1, Adrian S H Cheng, Michael Jerosch-Herold
1University of Oxford Centre for Clinical Magnetic Resonance Research, University of Oxford, Oxford, UK. joseph.selva@fmc.sa.gov.au
Insights
Percutaneous coronary intervention (PCI) can impair microcirculation, causing reduced myocardial perfusion reserve index (MPRI) in injured segments. However, this impairment shows improvement over time, suggesting potential for recovery after PCI.
Area of Science:
- Cardiovascular Imaging
- Interventional Cardiology
- Myocardial Perfusion
Background:
- Persistent microcirculatory dysfunction after percutaneous coronary intervention (PCI) is observed in some patients.
- Distal embolization of plaque contents is a suspected cause of this impairment.
- Investigating PCI-induced changes in myocardial perfusion reserve index (MPRI) is crucial.
Purpose of the Study:
- To evaluate changes in MPRI over time in myocardial segments with distal myonecrosis after PCI.
- To assess the impact of distal embolization on myocardial perfusion.
- To utilize high-resolution quantitative cardiovascular magnetic resonance imaging (CMR) for detailed analysis.
Main Methods:
- Forty patients undergoing PCI were assessed using pre-PCI and post-PCI CMR (24 hours and 6 months).
- Delayed-enhancement (DE) and first-pass perfusion imaging (rest and stress) were performed.
- MPRI was calculated as the ratio of hyperemic to resting myocardial blood flow.
Main Results:
- Twenty-one patients showed new distal hyperenhancement (injury) after PCI.
- MPRI increased in segments without injury but decreased significantly in segments with distal hyperenhancement.
- MPRI in injured segments improved by 6 months post-PCI, indicating partial recovery.
Conclusions:
- MPRI is reduced in myocardial segments with new distal irreversible injury 24 hours after PCI.
- These perfusion deficits are localized to the injured segments and do not affect the entire culprit vessel territory.
- The findings highlight the localized impact of PCI-related injury on myocardial perfusion and suggest a potential for recovery.
Background:
Studies have shown that a subset of patients demonstrate persistent impairment in microcirculatory function after percutaneous coronary intervention (PCI). Distal embolization of plaque contents has been postulated as the main mechanism for this. We sought to investigate this further by evaluating PCI-induced changes in myocardial perfusion reserve index (MPRI) over time in segments with "distal-type" procedure-related myonecrosis using high-resolution quantitative cardiovascular magnetic resonance imaging.
Methods And Results:
Forty patients undergoing PCI were studied with pre-PCI and 24-hour post-PCI delayed-enhancement magnetic resonance imaging and first-pass perfusion magnetic resonance imaging at rest and stress. Twenty patients underwent a third magnetic resonance imaging scan at 6 months. For perfusion imaging, 3 short-axis images were acquired during every heartbeat with a T1-weighted turboFLASH sequence. MPRI was calculated as the ratio of hyperemic to resting myocardial blood flow and subdivided according to the presence and location of new delayed hyperenhancement. Twenty-one patients demonstrated new distal hyperenhancement after PCI. Mean MPRI in revascularized myocardial segments not demonstrating new HE was significantly increased after the procedure (2.06 [95% CI, 1.99 to 2.13] before PCI and 2.52 [95% CI, 2.42 to 2.62] after PCI; P<0.001). In contrast, MPRI in segments with distal hyperenhancement was reduced after PCI (2.16 [95% CI, 1.95 to 2.37] before PCI; 2.00 [95% CI, 1.82 to 2.19] after PCI; mixed-model z=-4.82; P<0.001). Changes in mean MPRI 24 hours after PCI in segments upstream to new injury were not significantly different compared with perfusion changes in remote myocardium (z=-0.68; P=0.50). At 6 months after the procedure, mean MPRI in segments with new injury improved significantly compared with MPRI measured in these segments at 24 hours after PCI.
Conclusions:
MPRI is reduced in myocardial segments that demonstrate new distal irreversible injury at 24 hours after PCI. These reductions are confined to the segments with injury and do not affect the entire supply territory of the culprit vessel.
