Coronary Flow Capacity to Identify Stenosis Associated With Coronary Flow Improvement After Revascularization: A Combined Analysis From DEFINE FLOW and IDEAL

Robust Association Between Changes in Coronary Flow Capacity Following Percutaneous Coronary Intervention and Vessel-Oriented Outcomes and the Implication for Clinical Practice

Background

Coronary flow capacity (CFC) is a potentially important physiologic marker of ischemia for guiding percutaneous coronary intervention (PCI) indication, while the changes through PCI have not been investigated.

Objectives

To assess the determinants and prognostic implication of delta CFC, defined as the change in the CFC status following PCI.

Materials and Methods

From a single-center registry, a total of 450 patients with chronic coronary syndrome (CCS) who underwent fractional flow reserve (FFR)-guided PCI with pre-/post-PCI invasive coronary physiological assessments were included. Associations between PCI-related changes in thermodilution method-derived CFC categories and incident target vessel failure (TVF) were assessed.

Results

The mean (SD) age was 67.1 (10.0) years and there were 75 (16.7%) women. Compared with patients showing no change in CFC categories after PCI, patients with category worsened, +1, +2, and +3 category improved had the hazard ratio (95% CI) for incident TVF of 2.27 (0.95, 5.43), 0.85 (0.33, 2.22), 0.45 (0.12, 1.63), and 0.14 (0.016, 1.30), respectively (p for linear trends = 0.0051). After adjustment for confounders, one additional change in CFC status was associated with 0.61 (0.45, 0.83) times the hazard of TVF. CFC changes were largely predicted by the pre-PCI CFC status.

Conclusion

Coronary flow capacity changes following PCI, which was largely determined by the pre-PCI CFC status, were associated with the lower risk of incident TVF in patients with CCS who underwent PCI. The CFC changes provide a mechanistic explanation on potential favorable effect of PCI on reducing vessel-oriented outcome in lesions with reduced CFC and low FFR.

Differential Impact of Coronary Revascularization on Long-Term Clinical Outcome According to Coronary Flow Characteristics: Analysis of the International ILIAS Registry

BACKGROUND

Coronary pressure indices such as fractional flow reserve are the standard for guiding elective revascularization. However, considering additional coronary flow parameters could further individualize and optimize the decision on revascularization. We aimed to investigate the potentially differential prognostic associations of elective percutaneous coronary intervention (PCI) according to coronary flow properties represented by coronary flow reserve (CFR), coronary flow capacity (CFC), and baseline CFC (bCFC).

METHODS

From the ILIAS Registry (Inclusive Invasive Physiological Assessment in Angina Syndromes) composed of 16 hospitals globally from 7 countries, patients with obstructive coronary artery disease who underwent invasive coronary physiological assessment were included (N=2370 vessels). We assessed effect measure modifications of the association of PCI and 5-year target vessel failure according to CFR, CFC, and bCFC either assessed by Doppler-technique or thermodilution-method.

RESULTS

The mean age of the population was 63.3 years, and there were 1322 (73.6%) males. Median fractional flow reserve was 0.85, and PCI was performed in 600 (25.3%) vessels. Reduced CFR, CFC, and abnormal bCFC were defined in 988 (41.7%), 542 (22.9%), and 600 (25.3%) vessels, respectively. Significant effect measure modifications were observed by CFC either in odds ratio (P=0.0018), additive (P=0.029), and hazard ratio scale (P=0.0002). The absolute risk of 5-year target-vessel failure was higher if treated by PCI in vessels with normal CFC by 1.8 (-1.7 to 5.3) percent, while that was lower by -5.9 (-12 to -0.1) percent in those with reduced CFC. CFR and bCFC were not significant effect modifiers in any scales. Similar associations were observed in per-patient analyses, whereas the findings were less robust.

CONCLUSIONS

We observed qualitative effect measure modification of PCI and 5-year clinical outcomes according to CFC status in additive scale. CFR and bCFC were not robust effect modifiers. Therefore, CFC could be potentially used to optimize the patient selection for elective PCI treatment combined with fractional flow reserve.

The impact of coronary revascularization on vessel-specific coronary flow capacity and long-term outcomes: a serial [15O]H2O positron emission tomography perfusion imaging study

AIMS

Coronary flow capacity (CFC) integrates quantitative hyperaemic myocardial blood flow (hMBF) and coronary flow reserve (CFR) to comprehensively assess physiological severity of coronary artery disease (CAD). This study evaluated the effects of revascularization on CFC as assessed by serial [15O]H2O positron emission tomography (PET) perfusion imaging.

METHODS AND RESULTS

A total of 314 patients with stable CAD underwent [15O]H2O PET imaging at baseline and after myocardial revascularization to assess changes in hMBF, CFR, and CFC in 415 revascularized vessels. Using thresholds for ischaemia and normal perfusion, vessels were stratified in five CFC categories: myocardial steal, severely reduced CFC, moderately reduced CFC, minimally reduced CFC, and normal flow. Additionally, the association between CFC increase and the composite endpoint of death and non-fatal myocardial infarction (MI) was studied. Vessel-specific CFC improved after revascularization (P < 0.01). Furthermore, baseline CFC was an independent predictor of CFC increase (P < 0.01). The largest changes in ΔhMBF (0.90 ± 0.74, 0.93 ± 0.65, 0.79 ± 0.74, 0.48 ± 0.61, and 0.29 ± 0.66 mL/min/g) and ΔCFR (1.01 ± 0.88, 0.99 ± 0.69, 0.87 ± 0.88, 0.66 ± 0.91, and -0.01 ± 1.06) were observed in vessels with lower baseline CFC (P < 0.01 for both). During a median follow-up of 3.5 (95% CI 3.1-3.9) years, an increase in CFC was independently associated with lower rates of death and non-fatal MI (HR 0.43, 95% CI 0.19-0.98, P = 0.04).

CONCLUSION

Successful revascularization results in an increase in CFC. Furthermore, baseline CFC was an independent predictor of change in hMBF, CFR, and subsequently CFC. In addition, an increase in CFC was associated with a favourable outcome in terms of death and non-fatal MI.

Coronary Flow Capacity to Identify Stenosis Associated With Coronary Flow Improvement After Revascularization: A Combined Analysis From DEFINE FLOW and IDEAL

Background Coronary flow capacity (CFC), which is a categorical assessment based on the combination of hyperemic coronary flow and coronary flow reserve (CFR), has been introduced as a comprehensive assessment of the coronary circulation to overcome the limitations of CFR alone. The aim of this study was to quantify coronary flow changes after percutaneous coronary intervention in relation to the classification of CFC and the current physiological cutoff values of fractional flow reserve, instantaneous wave-free ratio, and CFR. Methods and Results Using the combined data set from DEFINE FLOW (Distal Evaluation of Functional Performance With Intravascular Sensors to Assess the Narrowing Effect -Combined Pressure and Doppler FLOW Velocity Measurements) and IDEAL (Iberian-Dutch-English), a total of 133 vessels that underwent intracoronary Doppler flow measurement before and after percutaneous coronary intervention were analyzed. CFC classified prerevascularization lesions as normal (14), mildly reduced (40), moderately reduced (31), and severely reduced (48). Lesions with larger impairment of CFC showed greater increase in coronary flow and vice versa (median percent increase in coronary flow by revascularization: 4.2%, 25.9%, 50.1%, and 145.5%, respectively; P<0.001). Compared with the conventional cutoff values of fractional flow reserve, instantaneous wave-free ratio, and CFR, an ischemic CFC defined as moderately to severely reduced CFC showed higher diagnostic accuracy with higher specificity to predict a >50% increase in coronary flow after percutaneous coronary intervention. Receiver operating characteristic curve analysis demonstrated that only CFC has a superior predictive efficacy to CFR (P<0.05). Multivariate analysis revealed lesions with ischemic CFC to be the independent predictor of a significant coronary flow increase after percutaneous coronary intervention (odds ratio, 10.7; 95% CI, 4.6-24.8; P<0.001). Conclusions CFC showed significant improvement of identification of lesions that benefit from revascularization compared with CFR with respect to coronary flow increase. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT02328820.