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Published on: April 13, 2015
Prognostic implication of thermodilution coronary flow reserve in patients with indeterminate pressure-bounded
Joo Myung Lee1, Tae-Min Rhee2, Doyeon Hwang3
1Division of Cardiology, Department of Internal Medicine, Heart Vascular Stroke Institute, Samsung Medical Center, Sungkyunkwan University, School of Medicine, Seoul, Republic of Korea.
Insights
Thermodilution-based CFR (thermo-CFR) offers prognostic value in patients with indeterminate pressure-bounded CFR (PB-CFR). Low thermo-CFR is linked to higher patient-oriented composite outcomes, improving risk prediction beyond FFR.
Area of Science:
- Cardiovascular Medicine
- Interventional Cardiology
- Diagnostic Imaging
Background:
- Pressure-bounded coronary flow reserve (PB-CFR) using pressure-only data leaves many patients indeterminate.
- Thermodilution-based CFR (thermo-CFR) is a potential alternative for assessing coronary flow.
- This study investigates the prognostic significance of thermo-CFR in patients with indeterminate PB-CFR.
Purpose of the Study:
- To evaluate the prognostic implication of thermo-CFR in patients with indeterminate PB-CFR.
- To determine if thermo-CFR can improve risk stratification for patient-oriented composite outcomes (POCO).
Main Methods:
- 170 patients with indeterminate PB-CFR and deferred revascularization were analyzed.
- Fractional flow reserve (FFR) and thermo-CFR were measured for all patients.
- POCO rates were compared between patients with low (≤2.0) and high thermo-CFR over a median follow-up of 1350 days.
Main Results:
- Patients with low thermo-CFR (21.2%) had a significantly higher POCO rate (30.6% vs. 3.0%) compared to those with high thermo-CFR.
- Adding thermo-CFR to FFR significantly improved the prediction model's discrimination and reclassification for POCO risk.
- The c-index increased from 0.545 to 0.766 (p=0.002) with the addition of thermo-CFR.
Conclusions:
- Low thermo-CFR is associated with a significantly higher risk of POCO in patients with indeterminate PB-CFR.
- Thermo-CFR provides additional prognostic information beyond FFR in this patient group.
- Thermodilution-based CFR is a valuable tool for risk stratification in indeterminate coronary flow reserve cases.
Background:
Recently, the concept of pressure-bounded coronary flow reserve (PB-CFR) has been introduced. However, using pressure-only data, a substantial proportion of patients could not be classified into high or low PB-CFR and remained as indeterminate PB-CFR. The current study evaluated the prognostic implication of thermodilution-based CFR (thermo-CFR) in patients with indeterminate PB-CFR.
Methods:
Among 199 patients (211 lesions) with indeterminate PB-CFR, 170 patients (179 lesions) with deferral of revascularization were analyzed for the current study. The rates of patient-oriented composite outcomes (POCO, a composite of all-cause mortality, any myocardial infarction, and any ischemia-driven revascularization) were compared according to thermo-CFR. All patients underwent fractional flow reserve (FFR) and thermo-CFR measurements. Thermo-CFR ≤ 2.0 was classified as low thermo-CFR. The median follow-up duration was 1350.0 (Q1-Q3 1252.0-1468.0) days.
Results:
Mean angiographic percent diameter stenosis, FFR, and thermo-CFR were 42.3 ± 13.9, 0.84 ± 0.06, and 3.10 ± 1.15, respectively. Among 170 patients, 36 patients (21.2%) showed low thermo-CFR. Patients with low thermo-CFR showed significantly higher rate of POCO compared to those with high thermo-CFR (30.6% vs. 3.0%, HR 12.117, 95% CI 3.854-38.091, p < 0.001). Adding thermo-CFR to a prediction model with FFR significantly increased discrimination and reclassification index for the risk of POCO (c-index 0.545 vs. 0.766, p = 0.002, category-free net reclassification index 1.169, p < 0.001, relative integrated discrimination index 31.828, p < 0.001).
Conclusions:
Patients with low thermo-CFR showed a significantly higher risk of POCO compared to those with high thermo-CFR among patients with indeterminate PB-CFR. Thermo-CFR showed additional prognostic implication, in addition to FFR, in patients with indeterminate PB-CFR.
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