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Prognostic Value of Microvascular Resistance Reserve Measured Immediately After PCI in Stable Coronary Artery Disease
Takeshi Nishi1,2, Tadashi Murai3, Katsuhisa Waseda4
1Division of Cardiovascular Medicine, Stanford University School of Medicine and Stanford Cardiovascular Institute, CA (T.N., W.F.F.).
Background:
Microvascular resistance reserve (MRR) has been proposed as a specific metric to quantify coronary microvascular function. The long-term prognostic value of MRR measured in stable patients immediately after percutaneous coronary intervention (PCI) is unknown. This study sought to determine the prognostic value of MRR measured immediately after PCI in patients with stable coronary artery disease.
Methods:
This study included 502 patients with stable coronary artery disease who underwent elective PCI and coronary physiological measurements, including pressure and flow estimation using a bolus thermodilution method after PCI. MRR was calculated as coronary flow reserve divided by fractional flow reserve times the ratio of mean aortic pressure at rest to that at maximal hyperemia induced by hyperemic agents. An abnormal MRR was defined as ≤2.5. Major adverse cardiac events (MACEs) were defined as a composite of all-cause mortality, any myocardial infarction, and target-vessel revascularization.
Results:
During a median follow-up of 3.4 years, the cumulative MACE rate was significantly higher in the abnormal MRR group (12.5 versus 8.3 per 100 patient-years; hazard ratio 1.53 [95% CI, 1.10-2.11]; P<0.001). A higher all-cause mortality rate primarily drove this difference. On multivariable analysis, a higher MRR value was independently associated with lower MACE and lower mortality. When comparing 4 subgroups according to MRR and the index of microcirculatory resistance, patients with both abnormal MRR and index of microcirculatory resistance (≥25) had the highest MACE rate.
Conclusions:
An abnormal MRR measured immediately after PCI in patients with stable coronary artery disease is an independent predictor of MACE, particularly all-cause mortality.
Insights
Abnormal microvascular resistance reserve (MRR) after percutaneous coronary intervention (PCI) predicts major adverse cardiac events (MACE), especially mortality, in stable coronary artery disease patients. This finding highlights MRR as a key prognostic indicator post-PCI.
Area of Science:
- Cardiology
- Vascular Physiology
- Interventional Cardiology
Background:
- Coronary microvascular function is crucial in cardiovascular health.
- Microvascular resistance reserve (MRR) is a metric for assessing coronary microvascular function.
- The prognostic significance of MRR post-percutaneous coronary intervention (PCI) in stable patients remains unclear.
Purpose of the Study:
- To evaluate the long-term prognostic value of MRR measured immediately after elective PCI.
- To determine if MRR is an independent predictor of major adverse cardiac events (MACE) in patients with stable coronary artery disease.
Main Methods:
- 502 stable coronary artery disease patients undergoing elective PCI were included.
- Coronary physiological measurements, including pressure and flow, were obtained post-PCI using bolus thermodilution.
- MRR was calculated, with abnormal defined as ≤2.5. MACE included all-cause mortality, myocardial infarction, and target-vessel revascularization.
Main Results:
- Over 3.4 years, abnormal MRR was linked to a higher MACE rate (12.5 vs. 8.3 per 100 patient-years).
- All-cause mortality was the primary driver of increased MACE in the abnormal MRR group.
- Higher MRR values independently predicted lower MACE and mortality.
Conclusions:
- Abnormal MRR post-PCI is an independent predictor of MACE in stable coronary artery disease.
- MRR is particularly associated with increased all-cause mortality.
- Combined assessment of MRR and index of microcirculatory resistance identifies high-risk patients.
