The influence of elective percutaneous coronary intervention on microvascular resistance: a serial assessment using the index of microcirculatory resistance

Association of Coronary Computed Tomography-Defined Myocardial Bridge With Pre- and Post-Procedural Fractional Flow Reserve in Patients Undergoing Elective Percutaneous Coronary Intervention

BACKGROUND

Myocardial bridge (MB) is a common coronary anomaly characterized by a tunneled course through the myocardium. Coronary computed tomography angiography (CCTA) can identify MB. The impact of MB detected by CCTA on coronary physiological parameters before and after percutaneous coronary intervention (PCI) is unknown.Methods and Results: We investigated 141 consecutive patients who underwent pre-PCI CCTA and fractional flow reserve (FFR)-guided elective PCI for de novo single proximal lesions in the left anterior descending artery (LAD). We compared clinical demographics and physiological parameters between patients with and without CCTA-defined MB. MB was identified in 46 (32.6%) patients using pre-PCI CCTA. The prevalence of diabetes was higher among patients with MB. Median post-PCI FFR values were significantly lower among patients with than without MB (0.82 [interquartile range 0.79-0.85] vs. 0.85 [interquartile range 0.82-0.89]; P=0.003), whereas pre-PCI FFR values were similar between the 2 groups. Multivariable linear regression analysis revealed that the presence of MB and greater left ventricular mass volume in the LAD territory were independently associated with lower post-PCI FFR values. Multivariable logistic regression analysis also revealed that the presence of MB and lower pre-PCI FFR values were independent predictors of post-PCI FFR values ≤0.80.

CONCLUSIONS

CCTA-defined MB independently predicted both lower post-PCI FFR as a continuous variable and ischemic FFR as a categorical variable in patients undergoing elective PCI for LAD.

Serial fractional flow reserve, coronary flow reserve and index of microcirculatory resistance after percutaneous coronary intervention in patients treated for stable angina pectoris assessed with PET

BACKGROUND

Cardiac 15 O-water PET is a noninvasive method to evaluate epicardial and microvascular dysfunction and further quantitate absolute myocardial blood flow (MBF).

AIM

The aim of this study was to assess the impact of revascularization on MBF and myocardial flow reserve (MFR) assessed with 15 O-water PET and invasive flow and pressure measurements.

METHODS

In 21 patients with single-vessel disease referred for percutaneous coronary intervention (PCI), serial PET perfusion imaging and fractional flow reserve (FFR), coronary flow reserve (CFR) and index of microcirculatory resistance (IMR) were performed during PCI and after 3 months.

RESULTS

In the affected myocardium, stress MBF and MFR increased significantly from before revascularization to 3 months after revascularization: stress MBF 2.4 ± 0.8 vs. 3.2 ± 0.8; P  < 0.001 and MFR 2.5 ± 0.8 vs. 3.4 ± 1.1; P  = 0.004. FFR and CFR increased significantly from baseline to after revascularization and remained stable from after revascularization to 3-month follow-up: FFR 0.64 ± 0.20 vs. 0.91 ± 0.06 vs. 0.91 ± 0.07; P  < 0.001; CFR 2.4 ± 1.2 vs. 3.6 ± 1.9 vs. 3.6 ± 1.9; P  < 0.001, whereas IMR did not change significantly: 30.3 ± 22.9 vs. 30.1 ± 25.3 vs. 31.9 ± 25.2; P  = ns. After revascularization, an increase in stress MBF was associated with an increase in FFR ( r  = 0.732; P  < 0.001) and an increase in MFR ( r  = 0.499; P  = 0.021). IMR measured before PCI was inversely associated with improvement in stress MBF, ( r  = -0.616; P  = 0.004).

CONCLUSION

Recovery of myocardial perfusion after PCI was associated with an increase in FFR 3 months after revascularization. Microcirculatory dysfunction was associated with less improvement in myocardial perfusion.

Machine-learning-based prediction of fractional flow reserve after percutaneous coronary intervention

BACKGROUND AND AIMS

Post-percutaneous coronary intervention (PCI) fractional flow reserve (FFR) reflects residual atherosclerotic burden and is associated with future events. How much post-PCI FFR can be predicted based on baseline basic information and the clinical relevance have not been investigated.

METHODS

We compiled a multicenter registry of patients undergoing pre- and post-PCI FFR. Machine-learning (ML) algorithms were designed to predict post-PCI FFR levels from baseline demographics, quantitative coronary angiography, and pre-PCI FFR. FFR deviation was defined as actual minus ML-predicted post-PCI FFR levels, and its association with incident target vessel failure (TVF) was evaluated.

RESULTS

Median (IQR) pre- and post-PCI FFR values were 0.71 (0.61, 0.77) and 0.88 (0.84, 0.93), respectively. The Spearman correlation coefficient of the actual and predicted post-PCI FFR was 0.54 (95% CI: 0.52, 0.57). FFR deviation was non-linearly associated with incident TVF (HR [95% CI] with Q3 as reference: 1.65 [1.14, 2.39] in Q1, 1.42 [0.98, 2.08] in Q2, 0.81 [0.53, 1.26] in Q4, and 1.04 [0.69, 1.56] in Q5). A model with polynomial function of continuous FFR deviation indicated increasing TVF risk for FFR deviation ≤0 but plateau risk with FFR deviation >0.

CONCLUSIONS

An ML-based algorithm using baseline data moderately predicted post-PCI FFR. The deviation of post-PCI FFR from the predicted value was associated with higher vessel-oriented event.

Index of microcirculatory resistance: state-of-the-art and potential applications in computational simulation of coronary artery disease

The dysfunction of coronary microcirculation is an important cause of coronary artery disease (CAD). The index of microcirculatory resistance (IMR) is a quantitative evaluation of coronary microcirculatory function, which provides a significant reference for the prediction, diagnosis, treatment, and prognosis of CAD. IMR also plays a key role in investigating the interaction between epicardial and microcirculatory dysfunctions, and is closely associated with coronary hemodynamic parameters such as flow rate, distal coronary pressure, and aortic pressure, which have been widely applied in computational studies of CAD. However, there is currently a lack of consensus across studies on the normal and pathological ranges of IMR. The relationships between IMR and coronary hemodynamic parameters have not been accurately quantified, which limits the application of IMR in computational CAD studies. In this paper, we discuss the research gaps between IMR and its potential applications in the computational simulation of CAD. Computational simulation based on the combination of IMR and other hemodynamic parameters is a promising technology to improve the diagnosis and guide clinical trials of CAD.

FFR=1.0 flow changes after percutaneous coronary intervention

BACKGROUND

The present study investigated the relationships between physiological indices and increased coronary flow during percutaneous coronary intervention (PCI) using a novel index of "anticipated maximum flow" [AMF; theoretical coronary flow of fractional flow reserve (FFR) = 1]. FFR-guided PCI aims to increase coronary flow, whereas recent studies have reported that PCI does not necessarily increase coronary flow despite improvement in FFR.

METHODS

This retrospective analysis was performed in 71 functionally significant lesions treated with elective PCI. AMF obtained by hyperemic average peak coronary flow velocity (h-APV) divided by FFR would not change after PCI given the constant microvascular resistance, which is the assumption of FFR as a surrogate of coronary flow. We evaluated the relationship between AMF and coronary flow during PCI.

RESULTS

Post-PCI AMF was significantly different from pre-PCI AMF (p = 0.022), which impacted discordance between FFR improvement and change in coronary flow. Coronary flow increase >50% was associated with smaller minimum lumen diameter (p = 0.010), greater diameter stenosis (p = 0.003), lower pre-PCI FFR (p < 0.001), lower pre-PCI coronary flow reserve (p = 0.001), higher pre-PCI hyperemic stenosis resistance (p < 0.001), lower pre-PCI h-APV (p = 0.001), and lower pre-PCI AMF (p = 0.031). Pre-PCI AMF provided significant incremental predictive capability for coronary flow increase >50% when added to the clinical model including pre-PCI FFR.

CONCLUSION

Pre-PCI AMF provided incremental ability to predict increased coronary flow after PCI and impacted the discordance between FFR improvement and increased coronary flow.

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.

A randomized controlled trial of a physiology-guided percutaneous coronary intervention optimization strategy: Rationale and design of the TARGET FFR study

Post-percutaneous coronary intervention (PCI) fractional flow reserve (FFR) ≥0.90 confers an improved cardiac prognosis. There are currently limited data available to determine how often it is possible to improve an angiographically acceptable but physiologically suboptimal result. A physiology-guided optimization strategy can achieve a clinically meaningful increase in the proportion of patients achieving a final post-PCI FFR ≥0.90 compared to standard care. Following angiographically successful PCI procedures, 260 patients will be randomized (1:1) to receive either a physiology-guided incremental optimization strategy (intervention group) or blinded post-PCI coronary physiology measurements (control group). Patients undergoing successful, standard-of-care PCI for either stable angina or non-ST-segment-elevation myocardial infarction who meet the study's inclusion and exclusion criteria will be eligible for randomization. The primary endpoint is defined as the proportion of patients with a final post-PCI FFR result ≥0.90. Secondary endpoints include change from baseline in Seattle Angina Questionnaire and EQ-5D-5L scores at 3 months and the rate of target vessel failure and its components (cardiac death, myocardial infarction, stent thrombosis, unplanned rehospitalization with target vessel revascularization) at 3 months and 1 year. 260 individual patients were successfully randomized between March 2018 and November 2019. Key baseline demographics of the study population are reported within. TARGET FFR is an investigator-initiated, prospective, single-center, randomized controlled trial of an FFR-guided PCI optimization strategy. The study has completed recruitment and is now in clinical follow-up. It is anticipated that primary results will be presented in Autumn 2020. ClinicalTrials.gov Identifier: NCT03259815. [Correction added on Apr 3 2020, after first online publication: Clinical Trials identifier added.].

Optical coherence tomography-defined plaque vulnerability in relation to functional stenosis severity stratified by fractional flow reserve and quantitative flow ratio

OBJECTIVES

We sought to investigate that the quantitative flow ratio (QFR) might be associated with optical coherence tomography (OCT)-defined plaque vulnerability.

BACKGROUND

Both functional stenosis severity and plaque instability are related to adverse clinical outcomes in patients with coronary artery disease. Recent studies have shown an association between physiological stenosis severity and the presence of thin-cap fibroatheroma (TCFA). Measurement of QFR is a novel method for rapid computational estimation of fractional flow reserve (FFR).

METHODS

We investigated 327 de novo intermediate-to-severe coronary lesions in 295 stable patients who underwent OCT, FFR, and QFR computation. The lesions were divided into tertiles based on either the FFR or QFR. The OCT findings were compared among these tertiles of FFR and QFR. Each tertile was defined as follows: FFR-T1 (FFR < 0.72), FFR-T2 (0.72 ≤ FFR ≤ 0.79), and FFR-T3 (FFR > 0.79) and QFR-T1 (QFR < 0.73), QFR-T2 (0.73 ≤ QFR ≤ 0.78), and QFR-T3 (QFR > 0.78).

RESULTS

The prevalence of OCT-defined TCFA showed graded differences in proportion to the QFR tertiles (25.0% vs. 12.8% vs. 6.6%, p = .003). An overall significant difference in the prevalence of TCFA was found among FFR tertiles (p = .048), although pairwise comparison did not show statistical significance. Compared with FFR-based classifications, the model that integrated the FFR and QFR categorization improved the incremental reclassification efficacy (relative integrated discrimination improvement, 0.069; p = .002; continuous net reclassification improvement, 0.356; p = .022) for predicting the presence of TCFA.

CONCLUSIONS

OCT-defined plaque instability was associated with the QFR in angiographically intermediate-to-severe lesions. Compared with the FFR alone, the QFR can provide incremental efficacy in predicting the presence of TCFA.

Changes in Index of Microcirculatory Resistance during PCI in the Left Anterior Descending Coronary Artery in Relation to Total Length of Implanted Stents

Aim

To investigate the relationship between stent length and changes in microvascular resistance during PCI in stable coronary artery disease (CAD).

Methods and Results

We measured fractional flow reserve (FFR), index of microcirculatory resistance (IMR), and coronary flow reserve (CFR) before and after stenting in 42 consecutive subjects with stable coronary artery undergoing PCI with stent in the LAD. Patients that had very long stent length (38–78 mm) had lower FFR before stenting than patients that had long (23–37 mm) and moderate (12–22 mm) stent length (0.59 (±0.16), 0.70 (±0.12), and 0.75 (±0.07); p=0.002). FFR improved after stenting and more so in subjects with very long stent length compared to long and moderate stent length (0.27 (s.d ± 16), 0.15 (s.d ± 0.12), and 0.12 (s.d ± 0.07); p for interaction = 0.013). Corrected IMR (IMR_corr) increased after stenting in subjects who had very long stent length, whereas IMR_corr was lower after stenting in subjects who had long or moderate stent length (4.6 (s.d. ± 10.7), −1.4 (s.d. ± 9,9), and −4.2 (s.d. ± 7.8); p for interaction = 0.009).

Conclusions

Changes in IMR during PCI in the LAD in stable CAD seem to be related to total length of stents implanted, possibly influencing post-PCI FFR. Larger studies are needed to confirm the relationship.

Clinical significance of concordance or discordance between fractional flow reserve and coronary flow reserve for coronary physiological indices, microvascular resistance, and prognosis after elective percutaneous coronary intervention

AIMS

We aimed to investigate the impact of concordance or discordance of fractional flow reserve (FFR) and coronary flow reserve (CFR) on coronary flow profiles and microvascular resistance after percutaneous coronary intervention (PCI), and the prognostic impact of the periprocedural physiological indices.

METHODS AND RESULTS

A total of 249 de novo physiologically significant coronary lesions from 231 patients who underwent FFR, CFR, and index of microcirculatory resistance (IMR) examinations before and after PCI were included. Baseline characteristics and physiological indices were compared between the concordant (FFR ≤0.80 and CFR <2.0, n=114) and discordant (FFR ≤0.80 and CFR ≥2.0, n=135) groups. Follow-up data were collected to determine predictors of cardiac events. Shortening of the mean transit time, CFR improvement, and decrease in the hyperaemic IMR were all significantly greater in the concordant territories. Cox proportional hazards analysis showed that a lower pre-PCI CFR was an independent predictor of adverse events at a median follow-up of 26.5 months, whereas neither the pre- nor post-PCI FFR was predictive of events. Event-free survival was significantly worse in patients with a lower pre-PCI CFR.

CONCLUSIONS

FFR/CFR concordantly abnormal territories provide a favourable benefit as assessed by coronary physiological indices after elective PCI. The pre-PCI CFR may predict adverse cardiac events.

The effect of elective implantation of the ABSORB bioresorbable vascular scaffold on coronary microcirculation: Serial assessment using the index of microcirculatory resistance

INTRODUCTION

Stenting with metal stents can affect microcirculatory function. The impact of BVS on the microvascular network has not been studied.

METHODS

A total of 30 patients with bifurcation disease of Medina (X,X,0) scheduled for elective PCI with the ABSORB BVS were studied. Pressure wire studies were performed before and after scaffold implantation and at a mean follow-up of 9 months. At each time point, FFR, IMR, and CFR were calculated using the thermodilution method.

RESULTS

Following scaffold implantation, FFR change from pre-PCI, post-PCI and follow-up was 0.76, 0.92 and 0.91, respectively (P < 0.001 from pre to post-PCI and P = 0.91 from post-PCI to follow-up). There was a statistically significant improvement between pre- and post-procedural IMR (median 27.7 to 17.9, P = 0.02) and CFR (median 2.2 to 2.9, P = 0.02). Median IMR at follow-up (23.6) remained numerically lower than pre-procedure but this was not statistically significant (P = 0.05). Similarly, while median CFR at follow-up remained at post-procedural level (2.9), this effect did not reach statistical significance (P = 0.06).

CONCLUSION

There is an immediate reduction in microvascular resistance after elective BVS implantation but this effect is not sustained long term.

Impact of Elective Percutaneous Coronary Intervention on Global Absolute Coronary Flow and Flow Reserve Evaluated by Phase-Contrast Cine-Magnetic Resonance Imaging in Relation to Regional Invasive Physiological Indices

Background:

Few studies have documented changes in global absolute coronary blood flow and global coronary flow reserve after percutaneous coronary intervention (PCI) in relation to regional physiological measures. Phase-contrast cine-magnetic resonance of the coronary sinus is a promising approach to quantify global absolute coronary blood flow. We aimed to assess the impact of elective PCI on global absolute coronary blood flow and global coronary flow reserve by quantifying coronary sinus flow (CSF) using phase-contrast cine-magnetic resonance in relation to regional physiological indices.

Methods and Results:

We prospectively studied 54 patients with stable angina undergoing elective PCI for a single proximal lesion. Phase-contrast cine-magnetic resonance was used to assess CSF and CSF reserve at rest and during maximum hyperemia, before and after PCI. Regional physiological indices were obtained during PCI. A complete data set was obtained in 50 patients. Hyperemic CSF increased significantly after PCI (pre-PCI, 230.2 [167.4–282.8] mL/min; post-PCI, 267.4 [224.1–346.2] mL/min; P <0.01), although 12 patients (24.0%) showed a decrease, despite successful PCI and improved fractional flow reserve. CSF reserve numerically, albeit not statistically significant ( P =0.19), increased from 2.65 (1.95–3.96) to 2.98 (2.13–4.32). Patients with decreased CSF after PCI were associated with significantly greater pre-PCI hyperemic CSF, lower global coronary vascular resistance, lower regional microcirculatory resistance, and higher fractional flow reserve (all P <0.01).

Conclusions:

Fractional flow reserve–guided PCI in patients with single de novo lesions was associated with increased absolute hyperemic CSF, although 24% of patients showed decreased hyperemic CSF, despite successful and uncomplicated PCI. The present approach combining regional and global physiological assessments may provide a novel insight into the dynamic behavior of the coronary hemodynamics and microvascular function after PCI.

Influence of visual-functional mismatch on coronary flow profiles after percutaneous coronary intervention: a propensity score-matched analysis

The aims of this study are to clarify whether discrepancies between angiographic and fractional flow reserve (FFR) measurements (visual-functional mismatch) influence coronary flow profiles after percutaneous coronary intervention. While current guidelines FFR-guided revascularization, clinical practice most commonly relies on angiographic evaluation, which may under- or over-estimate the functional relevance of the lesion. Our retrospective analysis involved 274 vessels from 264 patients with stable angina pectoris who underwent FFR, index of microvascular resistance, and coronary flow reserve (CFR) measurements before and after PCI. Visual-functional concordance and discordance (reverse mismatch) were defined as angiographic stenosis > 50% with FFR ≤ 0.80 and angiographic stenosis ≤ 50% with FFR ≤ 0.80, respectively. Propensity score-matched cohort included 132 lesions (66 lesions: concordant findings, 66 lesions: reverse mismatch). The change in coronary flow profiles after PCI was assessed in terms of FFR, CFR, index of microvascular resistance (IMR), and mean transit time (T_mn). Compared with concordant territories, reverse mismatch territories were associated with lower pre-PCI IMR, higher pre-PCI CFR, greater minimum lumen diameter and smaller reference diameter (all comparisons, P < 0.05). After propensity score matching, the prevalence and extent of coronary flow improvement after PCI, evaluated by CFR and T_mn, were both remained significantly greater in concordant territories (all comparisons, P < 0.05). The prevalence and extent of coronary flow improvement after PCI assessed by the physiologic indices was significantly greater in visual-functional concordant lesions, suggesting that these coronary physiologic changes were associated with discrepancy between angiographic measurements.

Coronary physiological assessment combining fractional flow reserve and index of microcirculatory resistance in patients undergoing elective percutaneous coronary intervention with grey zone fractional flow reserve

OBJECTIVES

The aim of this study is to investigate the association between fractional flow reserve (FFR) values and change in coronary physiological indices after elective percutaneous coronary intervention (PCI).

BACKGROUND

Decision making for revascularization when FFR is 0.75-0.80 is controversial.

METHODS

A retrospective analysis was performed of 296 patients with stable angina pectoris who underwent physiological examinations before and after PCI. To investigate the differences of coronary flow improvement between territories with low-FFR (<0.75) and grey-zone FFR (0.75-0.80), serial changes in physiological indices including mean transit time (Tmn), coronary flow reserve (CFR), and index of microcirculatory resistance (IMR) were compared between these two groups.

RESULTS

Compared to low-FFR territories, grey-zone FFR territories showed significantly lower prevalence of Tmn shortening, CFR improvement, and decrease in IMR (Tmn shorting, 63.9% vs. 87.0%, P < .001; CFR improvement, 63.0% vs. 75.7%, P = .019; IMR decrease, 51.3% vs. 63.3%, P = .040) and lower extent of their absolute changes (Tmn shorting, 0.06 (-0.03 to 0.16) vs. 0.22 (0.07-0.45), P < .001; CFR improvement, 0.45 (-0.32 to 1.87) vs. 1.08 (0.02-2.44), P < .01; IMR decrease, 0.2 (-44.0 to 31.3) vs. 2.9 (-2.9 to 11.8), P = .022). Multivariate analysis showed that pre-PCI IMR predicted improved coronary flow profile in both groups, whereas pre-PCI FFR predicted increased coronary flow indices in low-FFR territories.

CONCLUSIONS

Worsening of physiological indices after PCI was not uncommon in territories showing grey-zone FFR. Physiological assessment combining FFR and IMR may help identify patients who may benefit by PCI, particularly those in the grey zone.

Significance of Microvascular Function in Visual-Functional Mismatch Between Invasive Coronary Angiography and Fractional Flow Reserve

BACKGROUND

Despite a moderate correlation between angiographical stenosis and physiological significance, the mechanism of discordance has not been fully elucidated, particularly regarding the significance of microvascular function. This study sought to clarify whether microvascular function affects visual-functional mismatch between quantitative coronary angiography (QCA) and fractional flow reserve (FFR).

METHODS AND RESULTS

We assessed QCA, FFR, coronary flow reserve, and the index of microcirculatory resistance in 849 non-left-main coronary lesions with visually estimated intermediate stenoses from 532 patients. Clinical and lesion-specific characteristics and physiological parameters associated with mismatch and reverse mismatch were studied. Coronary flow reserve and index of microcirculatory resistance showed a weak, but significant, correlation with FFR (R=0.306, P<0.001 and R=0.158, P<0.001, respectively). Four hundred twenty-two lesions were visually nonsignificant (diameter stenosis assessed by QCA [QCA-DS] ≤50%) and 427 lesions were visually significant (QCA-DS >50%). Among visually nonsignificant lesions, FFR ≤0.80 (reverse mismatch) was observed in 129 lesions (30.6%). Among visually significant lesions, FFR >0.80 (mismatch) were observed in 179 lesions (41.9%). The significant predictors of reverse mismatch were male sex, nonculprit lesions of acute coronary syndrome, left anterior descending artery location, smaller QCA reference diameter, greater QCA-DS, lower coronary flow reserve, and lower index of microcirculatory resistance. Mismatch was associated with right coronary artery location, greater QCA reference diameter, smaller QCA-DS, lesion length, higher coronary flow reserve, and higher index of microcirculatory resistance.

CONCLUSIONS

There was a high prevalence of visual-functional mismatches between QCA and FFR. The discrepancy was related to clinical characteristics, lesion-specific factors, and microvascular resistance that was undistinguishable by coronary angiography, thus suggesting the importance of physiological lesion assessment.

Prevalence and Clinical Significance of Discordant Changes in Fractional and Coronary Flow Reserve After Elective Percutaneous Coronary Intervention

BACKGROUND

Fractional flow reserve (FFR) and coronary flow reserve (CFR) are well-validated physiological indices; however, changes in FFR and CFR after percutaneous coronary intervention (PCI) remain elusive. We sought to evaluate these changes and to investigate whether physiological indices predict cardiac event-free survival after PCI.

METHODS AND RESULTS

Physiological assessment of 220 stenoses from 220 patients was performed before and after PCI. The changes in FFR and CFR were studied, and factors associated with CFR change were investigated. Follow-up data were collected to determine the predictor of cardiac events. CFR increase was found in 158 (71.8%) territories, and 62 (28.2%) presented a decrease, whereas FFR increased in all 220 (100%) territories. Pre- and post-PCI percentage diameter stenoses were 57.7±11.2% and 7.48±4.79%, respectively. Post-PCI CFR increase was associated with pre-PCI indices including low FFR, low CFR and high microvascular resistance, and post-PCI hyperemic coronary flow increase. Post-PCI CFR decrease was not associated with significant post-PCI hyperemic coronary flow increase. At a median follow-up of 24.3 months, adverse event-free survival was significantly worse in patients with lower pre-PCI CFR (log-rank test λ2=7.26; P=0.007). Cox proportional hazards analysis showed that lower pre-PCI CFR (hazard ratio 0.73; 95% CI 0.55-0.97; P=0.028) was an independent predictor of adverse cardiovascular events after PCI.

CONCLUSIONS

CFR decrease after PCI was not uncommon, and discordant change in FFR and CFR was associated with high pre-PCI CFR, low pre-PCI microvascular resistance, and no significant post-PCI hyperemic coronary flow increase. Pre-PCI CFR, not post-PCI physiological indices, may help identify patients who require adjunctive management strategy after successful PCI.