Optical coherence tomography-derived predictors of stent expansion in calcified lesions

BACKGROUND

Severe coronary artery calcification is associated with stent underexpansion and subsequent stent failure.

AIMS

We aimed to identify optical coherence tomography (OCT)-derived predictors of absolute (minimal stent area [MSA]) and relative stent expansion in calcified lesions.

METHODS

This retrospective cohort study included patients who underwent percutaneous coronary intervention (PCI) with OCT assessment before and after stent implantation between May 2008 and April 2022. Pre-PCI OCT was used to assess calcium burden and post-PCI OCT was used to assess absolute and relative stent expansion.

RESULTS

A total of 361 lesions in 336 patients were analyzed. Target lesion calcification (defined as OCT-detected maximum calcium angle ≥ 30°) was present in 242 (67.0%) lesions. Following PCI, median MSA was 5.37 mm² in calcified lesions and 6.24 mm² in noncalcified lesions (p < 0.001). Median stent expansion was 78% in calcified lesions and 83% in noncalcified lesions (p = 0.325). In the subset of calcified lesions, average stent diameter, preprocedural minimal lumen area, and total calcium length were independent predictors of MSA in multivariable analysis (mean difference 2.69 mm² /mm² , 0.52 mm² /mm, and -0.28 mm² /5 mm, respectively, all p < 0.001). Total stent length was the only independent predictor of relative stent expansion (mean difference -0.465% per mm, p < 0.001). Calcium angle, thickness, and the presence of nodular calcification were not significantly associated with MSA or stent expansion in multivariable analyses.

CONCLUSION

Calcium length appeared to be the most important OCT-derived predictor of MSA, whereas stent expansion was mainly determined by total stent length.

Validation of Segmental Post-PCI Physiological Gradients With IVUS-Detected Focal Lesions and Stent Underexpansion

BACKGROUND

Segmental post-percutaneous coronary intervention (PCI) pressure gradients may detect residual disease and potential targets for optimization. However, universal definitions of relevant segmental gradients are lacking.

OBJECTIVES

The study sought to evaluate the diagnostic performance of post-PCI fractional flow reserve (FFR), distal coronary pressure-to-aortic pressure ratio (Pd/Pa), and diastolic pressure ratio (dPR) gradients to detect residual focal lesions and stent underexpansion as observed by intravascular ultrasound (IVUS).

METHODS

Patients from the IVUS-guided optimization arm of the FFR REACT (FFR-guided PCI Optimization Directed by High-Definition IVUS Versus Standard of Care) trial with complete IVUS and FFR pullback data were included. Patients with angiographically successful PCI and post-PCI FFR <0.90 underwent FFR, Pd/Pa, and IVUS pullbacks. dPR was calculated offline using dedicated software. Segmental pressure gradients (distal, in stent, and proximal) in segments ≥5 mm were evaluated against IVUS-detected residual disease (distal or proximal focal lesions and stent underexpansion).

RESULTS

A total of 139 vessels were included (mean post-PCI FFR: 0.83 ± 0.05, range 0.56-0.89). Focal distal and proximal lesions were detected by IVUS in 23 (17.4%) of 132 and 14 (12.6%) of 111 vessels, respectively, whereas stent underexpansion was present in 86 (61.9%) vessels. Diagnostic ability of segmental FFR gradients to predict IVUS-detected distal and proximal lesions was moderate to good (area under the curve [AUC]: 0.69 and 0.84, respectively) and poor to moderate for segmental Pd/Pa and dPR gradients (AUC ranging from 0.58 to 0.69). In-stent gradients had no discriminative ability to detect stent underexpansion (FFR AUC: 0.52; Pd/Pa AUC: 0.54; dPR AUC: 0.55).

CONCLUSIONS

In patients with post-PCI FFR <0.90, segmental post-PCI pressure gradients have moderate discriminative ability to identify IVUS-detected focal lesions but no discriminative ability to identify IVUS-detected stent underexpansion.

FFR-Guided PCI Optimization Directed by High-Definition IVUS Versus Standard of Care: The FFR REACT Trial

BACKGROUND

Post-percutaneous coronary intervention (PCI) fractional flow reserve (FFR) <0.90 is common and has been related to impaired patient outcome.

OBJECTIVES

The authors sought to evaluate if PCI optimization directed by intravascular ultrasound (IVUS) in patients with post-PCI FFR <0.90 could improve 1-year target vessel failure (TVF) rates.

METHODS

In this single-center, randomized, double-blind trial, patients with a post-PCI FFR <0.90 at the time of angiographically successful PCI were randomized to IVUS-guided optimization or the standard of care (control arm). The primary endpoint was TVF (a composite of cardiac death, spontaneous target vessel myocardial infarction, and clinically driven target vessel revascularization) at 1 year.

RESULTS

A total of 291 patients with post-PCI FFR <0.90 were randomized (IVUS-guided optimization arm: n = 145/152 vessels, control arm: n = 146/157 vessels). The mean post-PCI FFR was 0.84 ± 0.05. A total of 104 (68.4%) vessels in the IVUS-guided optimization arm underwent additional optimization including additional stenting (34.9%) or postdilatation only (33.6%), resulting in a mean increase in post-PCI FFR in these vessels from 0.82 ± 0.06 to 0.85 ± 0.05 (P < 0.001) and a post-PCI FFR ≥0.90 in 20% of the vessels. The 1-year TVF rate was comparable between the 2 study arms (IVUS-guided optimization arm: 4.2%, control arm: 4.8%; P = 0.79). There was a trend toward a lower incidence of clinically driven target vessel revascularization in the IVUS-guided optimization arm (0.7% vs. 4.2%, P = 0.06).

CONCLUSIONS

IVUS-guided post-PCI FFR optimization significantly improved post-PCI FFR. Because of lower-than-expected event rates, post-PCI FFR optimization did not significantly lower TVF at the 1-year follow-up.

Three-dimensional QCA-based vessel fractional flow reserve (vFFR) in Heart Team decision-making: a multicentre, retrospective, cohort study

OBJECTIVES

To evaluate the feasibility of three-vessel three-dimensional (3D) quantitative coronary angiography (QCA)-based fractional flow reserve (FFR) computation in patients discussed within the Heart Team in whom the treatment decision was based on angiography alone, and to evaluate the concordance between 3D QCA-based vessel FFR (vFFR)-confirmed functional lesion significance and revascularisation strategy as proposed by the Heart Team.

DESIGN

Retrospective, cohort.

SETTING

3D QCA-based FFR indices have not yet been evaluated in the context of Heart Team decision-making; consecutive patients from six institutions were screened for eligibility and three-vessel vFFR was computed by blinded analysts.

PARTICIPANTS

Consecutive patients with chronic coronary syndrome or unstable angina referred for Heart Team consultation. Exclusion criteria involved: presentation with acute myocardial infarction (MI), significant valve disease, left ventricle ejection fraction <30%, inadequate quality of angiogram precluding vFFR computation in all three epicardial coronary arteries (ie, absence of a minimum of two angiographic projections with views of at least 30° apart, substantial foreshortening/overlap of the vessel, poor contrast medium injection, ostial lesions, chronic total occlusions).

PRIMARY AND SECONDARY OUTCOME MEASURES

Discordance between vFFR-confirmed lesion significance and revascularisation was assessed as the primary outcome measure. Rates of major adverse cardiac events (MACE) defined as cardiac death, MI and clinically driven revascularisation were reported.

RESULTS

Of a total of 1003 patients were screened for eligibility, 416 patients (age 65.6±10.6, 71.2% male, 53% stable angina) were included. The most important reason for screening failure was insufficient quality of the angiogram (43%). Discordance between vFFR confirmed lesion significance and revascularisation was found in 124/416 patients (29.8%) corresponding to 149 vessels (46/149 vessels (30.9%) were reclassified as significant and 103/149 vessels (69.1%) as non-significant by vFFR). Over a median of 962 days, the cumulative incidence of MACE was 29.7% versus 18.5% in discordant versus concordant patients (p=0.031).

CONCLUSIONS

vFFR computation is feasible in around 40% of the patients referred for Heart Team discussion, a limitation that is mostly based on insufficient quality of the angiogram. Three vessel vFFR screening indicated discordance between vFFR confirmed lesion significance and revascularisation in 29.8% of the patients.

Diagnostic Accuracy of Coronary Angiography-Based Vessel Fractional Flow Reserve (vFFR) Virtual Stenting

3D coronary angiography-based vessel fractional flow reserve (vFFR) proved to be an accurate diagnostic alternative to invasively measured pressure wire based fractional flow reserve (FFR). The ability to compute post-PCI vFFR using pre-PCI vFFR virtual stent analysis is unknown. We aimed to assess the feasibility and diagnostic accuracy of pre-PCI vFFR virtual stenting analysis (residual vFFR) with post-PCI FFR as a reference. This is an observational, single-center retrospective cohort study including consecutive patients from the FFR-SEARCH registry. We blindly calculated residual vFFR from pre-PCI angiograms and compared them to invasive pressure-wire based post-PCI FFR. Inclusion criteria involved presentation with either stable or unstable angina or non-ST elevation myocardial infarction (NSTEMI), ≥1 significant stenosis in one of the epicardial coronary arteries (percentage diameter stenosis of >70% by QCA or hemodynamically relevant stenosis with FFR ≤0.80) and pre procedural angiograms eligible for vFFR analysis. Exclusion criteria comprised patients with ST elevation myocardial infarction (STEMI), coronary bypass grafts, cardiogenic shock or severe hemodynamic instability. Eighty-one pre-PCI residual vFFR measurements were compared to post-PCI FFR and post-PCI vFFR measurements. Mean residual vFFR was 0.91 ± 0.06, mean post-PCI FFR 0.91 ± 0.06 and mean post-PCI vFFR was 0.92 ± 0.05. Residual vFFR showed a high linear correlation (r = 0.84) and good agreement (mean difference (95% confidence interval): 0.005 (−0.002−0.012)) with post-PCI FFR, as well as with post-PCI-vFFR (r = 0.77, mean difference −0.007 (−0.015−0.0003)). Residual vFFR showed good accuracy in the identification of lesions with post-PCI FFR < 0.90 (sensitivity 94%, specificity 71%, area under the curve (AUC) 0.93 (95% CI: 0.86−0.99), p < 0.001). Virtual stenting using vFFR provided an accurate estimation of post-PCI FFR and post-PCI vFFR. Further studies are needed to prospectively validate a vFFR-guided PCI strategy.

Polarimetric Signatures of Coronary Thrombus in Patients With Acute Coronary Syndrome

BACKGROUND

Intravascular polarization-sensitive optical frequency domain imaging (PS-OFDI) offers a novel approach to measure tissue birefringence, which is elevated in collagen and smooth muscle cells, that in turn plays a critical role in healing coronary thrombus (HCT). This study aimed to quantitatively assess polarization properties of coronary fresh and organizing thrombus with PS-OFDI in patients with acute coronary syndrome (ACS).Methods and Results:The POLARIS-I prospective registry enrolled 32 patients with ACS. Pre-procedural PS-OFDI pullbacks using conventional imaging catheters revealed 26 thrombus-regions in 21 patients. Thrombus was manually delineated in conventional OFDI cross-sections separated by 0.5 mm and categorized into fresh thrombus caused by plaque rupture, stent thrombosis, or erosion in 18 thrombus-regions (182 frames) or into HCT for 8 thrombus-regions (141 frames). Birefringence of coronary thrombus was compared between the 2 categories. Birefringence in HCTs was significantly higher than in fresh thrombus (∆n=0.47 (0.37-0.72) vs. ∆n=0.25 (0.17-0.29), P=0.007). In a subgroup analysis, when only using thrombus-regions from culprit lesions, ischemic time was a significant predictor for birefringence (ß (∆n)=0.001 per hour, 95% CI [0.0002-0.002], P=0.023).

CONCLUSIONS

Intravascular PS-OFDI offers the opportunity to quantitatively assess the polarimetric properties of fresh and organizing coronary thrombus, providing new insights into vascular healing and plaque stability.

Impact of intravascular ultrasound findings in patients with a post PCI fractional flow reserve ≤0.85 on 2 year clinical outcome

BACKGROUND

Patients with a low post PCI fractional flow reserve (FFR) are at increased risk for future adverse cardiac events. The aim of the present study was to assess the impact of specific intravascular ultrasound (IVUS) findings in patients with a low post percutaneous coronary intervention (PCI) FFR on long-term clinical outcome.

METHODS

In a subgroup analysis, 100 vessels with an FFR value ≤0.85 underwent post PCI IVUS to further assess the potential determinants for low post PCI FFR. No further action was taken to improve post PCI FFR. The primary endpoint of this study was the event free survival of target vessel failure (TVF) at two years in patients with a post PCI FFR ≤0.85, which was defined as a composite of cardiac death, target vessel myocardial infarction or target vessel revascularization.

RESULTS

In patients with a post PCI FFR ≤0.85, TVF free survival rates were 88.5% vs. 95.5% for patients with versus without residual proximal lesions and 88.2% vs. 95.5% for patients with versus without residual distal lesions respectively (HR = 2.53, 95% confidence interval (CI) 0.52-12.25, p = .25 and HR = 2.60, 95% CI 0.54-12.59, p = .24 respectively). TVF free survival was 92.8% vs. 93.5% in patients with versus without stent underexpansion >20% (HR = 1.01, 95% CI 0.21-4.88, p = .99) and 89.3% vs. 97.8% in patients with versus without any residual focal lesion including lumen compromising hematoma (HR = 4.64, 95% CI 0.55-39.22, p = .18).

CONCLUSION

Numerically higher TVF rates were observed in patients with a post PCI FFR ≤0.85 and clear focal residual disease as assessed with IVUS.

Long-term outcome in patients treated with first- versus second-generation drug-eluting stents for the treatment of unprotected left main coronary artery stenosis

OBJECTIVE AND BACKGROUND

The study aim is to provide long-term clinical outcome after percutaneous coronary intervention (PCI) for unprotected left main coronary arteries (ULMCA) stenosis with the first-generation (1^st -gen) drug-eluting stents (DES) in comparison to 2^nd -gen DES, since this is largely unknown.

METHODS

Between May 2002, and December 2014, a consecutive series of 656 all-comer patients underwent a PCI for ULMCA stenosis at the Erasmus Medical Center. A total of 235 patients were treated with 1^st -gen DES, while a total of 421 patients were treated with 2^nd -gen DES.

RESULTS

Overall, the population consisted of 73% males and 58% presented with an acute coronary syndrome. Median follow-up time was 1,361 days (range from 0 to 5,031). At 5 years, the cumulative incidence of major adverse clinical events (the primary composite endpoint of all-cause death, any myocardial infarction or target lesion revascularization; MACE) did not differ between 1^st - and 2^nd -gen DES (36.8 vs. 38.6%, respectively, Log Rank p = .79, adjusted hazard ratio [HR] = 1.28 [95% confidence interval (CI) 0.94-1.74]). No difference was found in the individual endpoints of all-cause mortality (29.5 vs. 29% respectively, p = .88, adjusted HR = 1.19 [95% CI, 0.84-1.68]), target vessel myocardial infarction (5.0 vs. 8.4%, p = 0.17, adjusted HR = 1.75 [95% CI, 0.78-3.96]) and target lesion revascularization (8.1 vs. 9.8%, p = .94, adjusted HR = 1.16 [95% CI, 0.59-2.29]) between the 1^st - and 2^nd -gen DES cohorts, respectively.

CONCLUSIONS

In this large cohort of consecutive patients treated for ULMCA stenosis, no significant differences were found in the safety and efficacy of 1^st versus 2^nd -gen DES at 5 years follow-up.

Intravascular Polarimetry in Patients With Coronary Artery Disease

OBJECTIVES

The aims of this first-in-human pilot study of intravascular polarimetry were to investigate polarization properties of coronary plaques in patients and to examine the relationship of these features with established structural characteristics available to conventional optical frequency domain imaging (OFDI) and with clinical presentation.

BACKGROUND

Polarization-sensitive OFDI measures birefringence and depolarization of tissue together with conventional cross-sectional optical frequency domain images of subsurface microstructure.

METHODS

Thirty patients undergoing polarization-sensitive OFDI (acute coronary syndrome, n = 12; stable angina pectoris, n = 18) participated in this study. Three hundred forty-two cross-sectional images evenly distributed along all imaged coronary arteries were classified into 1 of 7 plaque categories according to conventional OFDI. Polarization features averaged over the entire intimal area of each cross section were compared among plaque types and with structural parameters. Furthermore, the polarization properties in cross sections (n = 244) of the fibrous caps of acute coronary syndrome and stable angina pectoris culprit lesions were assessed and compared with structural features using a generalized linear model.

RESULTS

The median birefringence and depolarization showed statistically significant differences among plaque types (p < 0.001 for both, one-way analysis of variance). Depolarization differed significantly among individual plaque types (p < 0.05), except between normal arteries and fibrous plaques and between fibrofatty and fibrocalcified plaques. Caps of acute coronary syndrome lesions and ruptured caps exhibited lower birefringence than caps of stable angina pectoris lesions (p < 0.01). In addition to clinical presentation, cap birefringence was also associated with macrophage accumulation as assessed using normalized SD.

CONCLUSIONS

Intravascular polarimetry provides quantitative metrics that help characterize coronary arterial tissues and may offer refined insight into coronary arterial atherosclerotic lesions in patients.

Fractional flow reserve guided percutaneous coronary intervention optimization directed by high-definition intravascular ultrasound versus standard of care: Rationale and study design of the prospective randomized FFR-REACT trial

BACKGROUND

Post percutaneous coronary intervention (PCI) fractional flow reserve (FFR) is a significant predictor of major adverse cardiac events (MACE). The rationale for low post procedural FFR values often remains elusive based on angiographic findings alone, warranting further assessment using an FFR pullback or additional intravascular imaging. It is currently unknown if additional interventions intended to improve the PCI, decrease MACE rates.

STUDY DESIGN

The FFR REACT trial is a prospective, single-center randomized controlled trial in which 290 patients with a post PCI FFR <0.90 will be randomized (1:1) to either standard of care (no additional intervention) or intravascular ultrasound (IVUS)-directed optimization of the FFR (treatment arm). Eligible patients are those treated with angiographically successful PCI for (un)stable angina or non-ST elevation myocardial infarction (MI). Assuming 45% of patients will have a post PCI FFR <0.90, approximately 640 patients undergoing PCI will need to be enrolled. Patients with a post PCI FFR ≥ 0.90 will be enrolled in a prospective registry. The primary end point is defined as a composite of cardiac death, target vessel MI and clinically driven target vessel revascularisation (target vessel failure) at 1 year. Secondary end points will consist of individual components of the primary end point, procedural success, stent thrombosis and correlations on clinical outcome, changes in post PCI Pd/Pa and FFR and IVUS derived dimensions. All patients will be followed for 3 years.

CONCLUSION

The FFR-REACT trial is designed to explore the potential benefit of HD-IVUS-guided PCI optimization in patients with a post PCI FFR <0.90 (Dutch trial register: NTR6711).