Comprehensive Assessment of Myocardial Ischemia Mechanisms in the Catheterization Laboratory: Design and Rationale of the Advanced Invasive Diagnosis Strategy for Patients with Stable Coronary Syndromes Undergoing Coronary ANGIOgraphy - the AID-ANGIO Study.

BACKGROUND: The diagnostic yield of invasive coronary angiography (ICA) to identify obstructive coronary artery disease in the context of chronic coronary syndromes (CCS) is very low. Furthermore, myocardial ischemia may have a non-obstructive origin, which cannot be detected by ICA. METHODS: AID-ANGIO is an observational, prospective, single-cohort, multicenter study, intended to evaluate the diagnostic yield of adopting a hierarchical strategy to assess obstructive and non-obstructive causes of myocardial ischemia in an all-comers population of patients with CCS at the time of ICA. The primary endpoint will investigate the additional diagnostic value of such strategy over angiography alone regarding the identification of ischemia-generating mechanisms. SUMMARY: An estimated sample of consecutive 260 patients with CCS referred by their clinicians to ICA, will be enrolled. In a stepwise manner, a conventional ICA will be performed as the initial diagnostic tool. Those patients with severe-grade stenosis will not undergo further assessment and an obstructive origin for myocardial ischemia will be assumed. Subsequently, the remainder with intermediate-grade stenosis will be assessed with pressure guidewires. Those with a negative result from physiological evaluation and those without epicardial coronary stenosis will be further studied for ischemia of non-obstructive origin, including microvascular dysfunction and vasomotor disorders. The study will be conducted in two steps. Firstly, ICA images will be displayed to patient's referring clinicians, who will be asked to identify the existent epicardial stenosis, their angiographic severity and probable physiological relevance, together with a tentative therapeutic approach. Then, the diagnostic algorithm will continue to be applied and, considering the whole gathered information, a definite therapeutic plan will be consensually established by the interventional cardiologist and patient's referring clinicians. CONCLUSION: The AID-ANGIO study will assess the additional diagnostic yield of a hierarchical strategy over ICA alone to identify ischemia-generating mechanisms in patients with CCS and its impact on therapeutic approach. Positive results of the study might support a streamlined invasive diagnostic process for patients with CCS.

Angiography-derived assessment of coronary microcirculatory resistance in patients with suspected myocardial ischaemia and non-obstructive coronary arteries.

BACKGROUND: Myocardial ischaemia with non-obstructive coronary arteries (INOCA) represents a challenging and frequent, but largely underdiagnosed, condition. AIMS: We aimed to investigate the feasibility and diagnostic value of angiography-derived coronary microcirculatory resistance in patients with INOCA syndrome. METHODS: This is an investigator-driven, prospective and blinded study. The diagnostic yield of angiography-derived index of coronary microcirculatory resistance (angio-IMR) was investigated against thermodilution-derived IMR (thermo-IMR) in patients with clinically indicated coronary angiography due to suspected myocardial ischaemia and angiographically normal or non-obstructive coronary arteries. The angio-IMR was derived from resting angiograms (contrast-flow angio-IMR [cAngio-IMR]) by an expert analyst blinded to the thermo-IMR. An independent, blinded, physiology core laboratory analysed the raw intracoronary physiology data and provided the final thermo-IMR values. RESULTS: A total of 104 patients (108 coronary vessels) were analysed after fulfilling predefined inclusion criteria. Most patients were female (67%). Obstructive epicardial disease was angiographically (percent diameter stenosis <50%) and physiologically (fractional flow reserve>0.80) ruled out in all cases. Median thermo-IMR and cAngio-IMR were 16.6 (12.7, 23.0) and 16.8 (12.8, 23.1) units, respectively (median difference -0.31, 95% confidence interval: -1.53 to 1.00; p=0.654). cAngio-IMR showed good correlation (Pearson coefficient 0.76; p<0.001), agreement (mean bias 0.4), discriminatory power (area under the curve from the receiver operator characteristics 0.865; p<0.001) and accuracy (85%), compared to thermo-IMR (≥25 U). CONCLUSIONS: Evaluating coronary microcirculatory resistance in patients with INOCA syndrome using cAngio-IMR is feasible and accurate. By circumventing the need of coronary instrumentation and hyperaemic drugs, this method may facilitate the assessment of coronary microcirculatory resistance in patients with suspected INOCA. CLINICALTRIALS: gov: NCT04827498.

Optical coherence tomography in coronary atherosclerosis assessment and intervention.

Since optical coherence tomography (OCT) was first performed in humans two decades ago, this imaging modality has been widely adopted in research on coronary atherosclerosis and adopted clinically for the optimization of percutaneous coronary intervention. In the past 10 years, substantial advances have been made in the understanding of in vivo vascular biology using OCT. Identification by OCT of culprit plaque pathology could potentially lead to a major shift in the management of patients with acute coronary syndromes. Detection by OCT of healed coronary plaque has been important in our understanding of the mechanisms involved in plaque destabilization and healing with the rapid progression of atherosclerosis. Accurate detection by OCT of sequelae from percutaneous coronary interventions that might be missed by angiography could improve clinical outcomes. In addition, OCT has become an essential diagnostic modality for myocardial infarction with non-obstructive coronary arteries. Insight into neoatherosclerosis from OCT could improve our understanding of the mechanisms of very late stent thrombosis. The appropriate use of OCT depends on accurate interpretation and understanding of the clinical significance of OCT findings. In this Review, we summarize the state of the art in cardiac OCT and facilitate the uniform use of this modality in coronary atherosclerosis. Contributions have been made by clinicians and investigators worldwide with extensive experience in OCT, with the aim that this document will serve as a standard reference for future research and clinical application.

Association between patient age, microcirculation, and coronary stenosis assessment with fractional flow reserve and instantaneous wave-free ratio.

OBJECTIVES: To investigate the effect of aging on coronary stenosis functional assessment with fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR). BACKGROUND: Limited data exist regarding the impact of patient age on these coronary pressure indices. METHODS: We analyzed 514 patients with coronary stenosis interrogated with intravascular physiology. The influence of patient age on FFR, iFR, and microcirculation-related indices was investigated. Vessel-oriented composite outcome (VOCO) was assessed in the FFR-based deferred population according to iFR, coronary flow reserve (CFR), and age. RESULTS: FFR increased (r = 0.128, p = 0.004), iFR remained unchanged (r = -0.001, p = 0.980), and CFR decreased (r = -0.095, p = 0.001) with patient age. Relationship between FFR and CFR differed across age groups (r = 0.263 in <60 years old vs. r = 0.124 in ≥60 years old, p = 0.0056), whereas iFR correlated to CFR similarly regardless age (r = 0.283 in <60 years old vs. r = 0.219 in ≥60 years old, p = 0.3781). No differences were found on angiographic stenosis severity (%DS 47.4 in <60 years old and 49.8 in ≥60 years old, p = 0.317). At 5 years, FFR-based revascularisation deferral in patients ≥60 years old was associated with more VOCO when either iFR (25%) or CFR (16.9%) were abnormal, compared to patients with normal iFR (6.3%) or normal CFR (4.6%) (log-rank p < 0.001). This difference in clinical outcomes was not observed in younger patients. CONCLUSIONS: FFR values increased progressively with patient age, potentially associated with age-related changes in the coronary microcirculation. Conversely, iFR values remained unchanged across the patient age spectrum. In ≥60 years old patients with revascularisation deferral based on FFR, both abnormal iFR and CFR values were associated with worse long-term patient outcomes.

Human vs. machine vs. core lab for the assessment of coronary atherosclerosis with lumen and vessel contour segmentation with intravascular ultrasound.

A machine learning (ML) algorithm for automatic segmentation of intravascular ultrasound was previously validated. It has the potential to improve efficiency, accuracy and precision of coronary vessel segmentation compared to manual segmentation by interventional cardiology experts. The aim of this study is to compare the performance of human readers to the machine and against the readings from a Core Laboratory. This is a post-hoc, cross-sectional analysis of the IBIS-4 study. Forty frames were randomly selected and analyzed by 10 readers of varying expertise two separate times, 1 week apart. Their measurements of lumen, vessel, plaque areas, and plaque burden were performed in an offline software. Among humans, the intra-observer variability was not statistically significant. For the total 80 frames, inter-observer variability between human readers, the ML algorithm and Core Laboratory for lumen area, vessel area, plaque area and plaque burden were not statistically different. For lumen area, however, relative differences between the human readers and the Core Lab ranged from 0.26 to 12.61%. For vessel area, they ranged from 1.25 to 9.54%. Efficiency between the ML algorithm and the readers differed notably. Humans spent 47 min on average to complete the analyses, while the ML algorithm took on average less than 1 min. The overall lumen, vessel and plaque means analyzed by humans and the proposed ML algorithm are similar to those of the Core Lab. Machines, however, are more time efficient. It is warranted to consider use of the ML algorithm in clinical practice.

Non-invasive assessment of endothelial function in patients with spontaneous coronary artery dissection: A case-control study.

BACKGROUND: The physiopathology underlying spontaneous coronary artery dissection remains largely unknown. Endothelial dysfunction is an early feature of many vascular disorders. We sought to determine the endothelial function assessed by reactive hyperemia peripheral arterial tonometry (RH-PAT) in patients with SCAD and compare it to that of non-SCAD patients with similar cardiovascular risk profile. METHODS: This is a case-control study with the participation of 2 centers. Patients (cases) were diagnosed with SCAD between 2008 and 2018. Control subjects were individually matched 2:1 to SCAD cases from a cohort recruited for assessment with RH-PAT between 2006 and 2013. The primary measure variable was the mean difference in the log-transformed reactive hyperemia index (LnRH-PAT Index) between groups. RESULTS: LnRH-PAT data from 23 patients with SCAD and 46 matched controls were analyzed. No significant differences were noted in the matching variables (overall, 95.7% female with mean age 52.7 years). In the SCAD group, more patients reported migraine (61 vs. 21%) and more patients were on betablockers (70 vs 28%), ACE inhibitors (65 vs. 13%) and statins (70 vs. 28%), all differences statistically significant. The mean LnRH-PAT value was 0.55 ± 0.22 in patients with SCAD and 0.77 ± 0.23 in controls (mean difference: 0.22, p < 0.001). CONCLUSIONS: In this observational study, patients with SCAD had a poorer endothelial function than similar subjects without prior SCAD. This finding opens a new venue in the research of the physio pathologic mechanisms underlying SCAD.

Sex Differences in Long-Term Outcomes in Patients With Deferred Revascularization Following Fractional Flow Reserve Assessment: International Collaboration Registry of Comprehensive Physiologic Evaluation.

Background Sex-specific differences may influence prognosis after deferred revascularization following fractional flow reserve (FFR) measurement. This study sought to investigate the sex differences in long-term prognosis of patients with deferred revascularization following FFR assessment. Methods and Results A total of 879 patients (879 vessels) with deferred revascularization with FFR >0.75 who underwent FFR and coronary flow reserve measurements were enrolled from 3 countries (Korea, Japan, and Spain). Long-term outcomes were assessed in 649 men and 230 women by the patient-oriented composite outcome (POCO, a composite of any death, any myocardial infarction, and any revascularization). We applied inverse-probability weighting based on propensity scores to account for differences at baseline between women and men (age, hyperlipidemia, diabetes mellitus, diameter stenosis, lesion length, multivessel disease, FFR, coronary flow reserve. The median follow-up duration was 1855 days (745-1855 days). Median FFR values were 0.88 (0.83-0.93) in men and 0.89 (0.85-0.94) in women, respectively. The occurrences of POCO were significantly high in men compared with that in women (10.5% versus 4.2%, P=0.007). Kaplan-Meier analysis revealed that women had a significantly lower risk of POCO (χ2=7.2, P=0.007). Multivariate COX proportional hazards regression analysis revealed that age, male, diabetes mellitus, diameter stenosis, lesion length, and coronary flow reserve were independent predictors of POCO. After applying IPW, the hazard ratio of males for POCO was 2.07 (95% CI, 1.07-4.04, P=0.032). Conclusions This large multinational study reveals that long-term outcome differs between women and men in favor of women after FFR-guided revascularization deferral. Clinical Trial Registration URL: http://www.ClinicalTrials.gov. Unique identifier: NCT02186093.

Influence of Microcirculatory Dysfunction on Angiography-Based Functional Assessment of Coronary Stenoses.

OBJECTIVES: The authors sought to evaluate the influence of coronary microcirculatory dysfunction (CMD) on the diagnostic performance of the quantitative flow ratio (QFR). BACKGROUND: Functional angiographic assessment of coronary stenoses based on fluid dynamics, such as QFR, constitutes an attractive alternative to fractional flow reserve (FFR). However, it is unknown whether CMD affects the reliability of angiography-based functional indices. METHODS: FFR and the index of microcirculatory resistance (IMR) were measured in 300 vessels (248 patients) as part of a multicenter international registry. QFR was calculated at a blinded core laboratory. Vessels were classified into 2 groups according to microcirculatory status: low IMR (<23 U), and high IMR (≥23 U, CMD). The impact of CMD on the diagnostic performance of QFR, as well as on incremental value of QFR over quantitative angiography, was assessed using FFR as reference. RESULTS: Percent diameter stenosis (%DS) and FFR were similar in low- and high-IMR groups (%DS 51 ± 12% vs. 53 ± 11%; p = 0.16; FFR 0.80 ± 0.11 vs. 0.81 ± 0.11; p = 0.23, respectively). In the overall cohort, classification agreement (CA) between QFR and FFR and diagnostic efficiency of QFR (area under the receiver-operating characteristics curve [AUC]) were high (CA: 88%; AUC: 0.93 [95% confidence interval (CI): 0.90 to 0.96]). However, when assessed according to microcirculatory status, a significantly lower CA and AUC of QFR were found in the high-IMR group as compared with the low-IMR group (CA: 76% vs. 92%; p < 0.001; AUC: 0.88 [95% CI: 0.79 to 0.94] vs. 0.96 [95% CI: 0.92 to 0.98]; p < 0.05). Compared with angiographic assessment, QFR increased by 0.20 (p < 0.001) and by 0.16 (p < 0.001) the AUC of %DS in low- and high-IMR groups, respectively. Independent predictors of misclassification between QFR and FFR were high IMR and acute coronary syndrome. CONCLUSIONS: CMD decreases the diagnostic performance of QFR. However, even in the presence of CMD, QFR remains superior to angiography alone in ascertaining functional stenosis severity.

Coronary aneurysms in the acute patient: Incidence, characterization and long-term management results.

BACKGROUND: Coronary aneurysms (1.5 times dilation the reference-vessel) are uncommon and have been diagnosed with increasing frequency with coronary angiography. The incidence varies from 1.5% to 5%. Reported complications are multiple: thrombosis, distal embolization, rupture and vasospasm, causing ischemia, heart failure or arrhythmias. However, the natural history and prognosis remains obscure. We aimed to describe the characteristics of acute patients with coronary aneurysms. METHODS: Prospective coronariography registry of patients with the diagnosis of coronary aneurysm between 2002 and 2013. Among 51,555 consecutive coronary angiograms, 414 patients with aneurysms were reported, of which 256 were considered acute (82% NSTE-ACS). RESULTS: Predominantly male (80%, mean age 65.5years), cardiovascular risk factors were common (hypertension 65%, dyslipidemia 65%, obesity 25%, diabetes mellitus 28.5%, and smokers 67%). With frequent coronary stenoses (94%), mostly with one aneurysm (80%), it was observed more frequently in the anterior descending artery. After a median follow-up of 52months, 53 died (14 cardiac causes) and 42% presented a cardiovascular event. Complications from the aneurysm were found in 4. The duration of dual antiplatelet therapy, LVEF, age and peripheral vascular disease highlighted in the multivariate analysis of death. CONCLUSION: The presence of coronary aneurysms in patients undergoing coronary angiography with an acute event is low. Patients who present them also have a large burden of atherosclerotic risk factors. In the long-term, the probability of cardiovascular complications is high, but only a small proportion are due to the aneurysm itself. A more intense and prolonged antithrombotic treatment may result in lower mortality rates.

Influence of the amount of myocardium subtended to a coronary stenosis on the index of microcirculatory resistance. Implications for the invasive assessment of microcirculatory function in ischaemic heart disease.

AIMS: The index of microcirculatory resistance (IMR) is increasingly used to quantify microcirculatory function. However, in normal coronary arteries, resistance increases with the branching structure of the coronary tree, which suggests that IMR could be influenced by the amount of downstream myocardial mass (MM). We aimed to evaluate the influence of the amount of MM subtended to an intermediate stenosis on the IMR. METHODS AND RESULTS: IMR, fractional flow reserve and coronary flow reserve (CFR) were measured in 123 coronary arteries (102 patients) with intermediate stenosis. Jeopardised MM was estimated with the Myocardial Jeopardy Index (MJI). MM was inversely associated with IMR (R.

Low coronary microcirculatory resistance associated with profound hypotension during intravenous adenosine infusion: implications for the functional assessment of coronary stenoses.

BACKGROUND: Intravenous adenosine infusion produces coronary and systemic vasodilatation, generally leading to systemic hypotension. However, adenosine-induced hypotension during stable hyperemia is heterogeneous, and its relevance to coronary stenoses assessment with fractional flow reserve (FFR) remains largely unknown. METHODS AND RESULTS: FFR, coronary flow reserve, and index of microcirculatory resistance were measured in 93 stenosed arteries (79 patients). Clinical and intracoronary measurements were analyzed among tertiles of the percentage degree of adenosine-induced hypotension, defined as follows: %ΔP(a)=-[100-(hyperemic aortic pressure×100/baseline aortic pressure)]. Overall, %ΔP(a) was -13.6±12.0%. Body mass index was associated with %ΔP(a) (r=0.258; P=0.025) and obesity, an independent predictor of profound adenosine-induced hypotension (tertile 3 of %ΔP(a); odds ratio, 3.95 [95% confidence interval, 1.48-10.54]; P=0.006). %ΔP(a) was associated with index of microcirculatory resistance (ρ=0.311; P=0.002), coronary flow reserve (r=-0.246; P=0.017), and marginally with FFR (r=0.203; P=0.051). However, index of microcirculatory resistance (ß=0.003; P<0.001) and not %ΔP(a) (ß=-0.001; P=0.564) was a predictor of FFR. Compared with tertiles 1 and 2 of %ΔP(a) (n=62 [66.6%]), stenoses assessed during profound adenosine-induced hypotension (n=31 [33.3%]) had lower index of microcirculatory resistance (12.4 [8.6-22.7] versus 20 [15.8-35.5]; P=0.001) and FFR values (0.77±0.13 versus 0.83±0.12; P=0.021), as well as a nonsignificant increase in coronary flow reserve (2.5±1.1 versus 2.2±0.87; P=0.170). CONCLUSIONS: The modification of systemic blood pressure during intravenous adenosine infusion is related to hyperemic microcirculatory resistance in the heart. Profound adenosine-induced hypotension is associated with obesity, lower coronary microcirculatory resistance, and lower FFR values.

Morphometric assessment of coronary stenosis relevance with optical coherence tomography: a comparison with fractional flow reserve and intravascular ultrasound.

OBJECTIVES: The study sought to assess the diagnostic efficiency of optical coherence tomography (OCT) in identifying hemodynamically severe coronary stenoses as determined by fractional flow reserve (FFR). Concomitant OCT and intravascular ultrasound (IVUS) area measurements were performed in a subgroup of patients to compare the diagnostic efficiency of both techniques. BACKGROUND: The value of OCT to determine stenosis severity remains unsettled. METHODS: Sixty-one stenoses with intermediate angiographic severity were studied in 56 patients. Stenoses were labeled as severe if FFR ≤0.80. OCT interrogation was performed in all cases, with concomitant IVUS imaging in 47 cases. RESULTS: Angiographic stenosis severity was 50.9 ± 8% diameter stenosis with 1.28 ± 0.3 mm minimal lumen diameter. FFR was ≤0.80 in 28 (45.9%) stenoses. An overall moderate diagnostic efficiency of OCT was found (area under the curve [AUC]: 0.74; 95% confidence interval [CI]: 0.61 to 0.84), with sensitivity/specificity of 82%/63% associated with an optimal cutoff value of 1.95 mm(2). Comparison of the results in patients with simultaneous IVUS and OCT imaging revealed no significant differences in the diagnostic efficiency of OCT (AUC: 0.70; 95% CI: 0.55 to 0.83) and IVUS (AUC. 0.63; 95% CI: 0.47 to 0.77; p = 0.19). Sensitivity/specificity for IVUS was 67%/65% for an optimal cutoff value of 2.36 mm(2). In the subgroup of small vessels (reference diameter <3 mm) OCT showed a significantly better diagnostic efficiency (AUC: 0.77; 95% CI: 0.60 to 0.89) than IVUS (AUC: 0.63; 95% CI: 0.46 to 0.78) to identify functionally significant stenoses (p = 0.04). CONCLUSIONS: OCT has a moderate diagnostic efficiency in identifying hemodynamically severe coronary stenoses. Although OCT seems slightly superior to IVUS for this purpose (particularly in vessels <3 mm), its low specificity precludes its use as a substitute of FFR for functional stenosis assessment.

[Assessment of dynamic coronary plaque changes and the clinical consequences in type-II diabetic patients: a serial intracoronary ultrasound study]. / Evaluación de los cambios dinámicos de las placas coronarias y sus consecuencias clínicas en pacientes con diabetes mellitus tipo 2: un estudio de ecografía intracoronaria seriada.

INTRODUCTION AND OBJECTIVES: One of the aims of secondary prevention is to achieve plaque stabilization. This study sought to investigate the clinical consequences and predictive factors of the change in the type of plaque (CTP) as assessed by serial intracoronary ultrasound in type II diabetic patients with known coronary artery disease. METHODS: 237 segments (45 patients) from the DIABETES I, II, and III trials were included. Intracoronary ultrasound from motorized pullbacks (0.5mm/s) after index procedure and at 9-month angiographic follow-up was performed in the same coronary segment. Nontreated mild lesions (angiographic stenosis <25%) with ≥0.5mm plaque thickening and ≥5mm of length assessed by intracoronary ultrasound were included. As different types of plaques may be encountered throughout a given coronary lesion, each study lesion was divided into 3 segments for serial quantitative and qualitative analyses. Statistical adjustment by multiple lesion segments per patient (generalized estimating equations method) was performed. A CTP was defined as any qualitative change in plaque type at follow-up. At 1-year follow-up, major adverse cardiac events - death, myocardial infarction and target vessel revascularization) - were recorded. RESULTS: A CTP was observed in 48 lesions (20.2%) and occurred more frequently (52.1%) in mixed plaques. Independent predictors of CTP were glycated hemoglobin levels (odds ratio [OR] 1.2; 95% confidence interval [CI] 1.01-1.5; P=.04); glycoprotein IIb-IIIa inhibitors (OR 0.3; 95% CI 0.1-0.7; P=.004) and statin administration (OR 0.3; 95% CI 0.1-0.8; P=.02). At 1-year follow-up CTP was associated with an increase in major adverse cardiac events rate (CTP 20.8% vs non-CTP 13.8%, P=.008; hazard ratio=1.9, 95% CI 1.3-1.9, P=.01). CONCLUSIONS: Qualitative changes in mild stenosis documented by intracoronary ultrasound in type II diabetics are associated with suboptimal secondary prevention and may have clinical consequences. Full English text available from: www.revespcardiol.org.

A comparison of the distribution of necrotic core in bifurcation and non-bifurcation coronary lesions: an in vivo assessment using intravascular ultrasound radiofrequency data analysis.

AIMS: High-risk plaques are prone to develop at the site of coronary vessel bifurcations. The distribution of necrotic core at bifurcation lesions (BL) is known, however, little has been described on the necrotic core distribution in non-BLs. Therefore we compared the distribution of necrotic core between BL and non-BLs in coronary arteries using IVUS-VH imaging. METHODS AND RESULTS: A total of 129 patients (112 non-BL and 108 BL) were included. The lesions were divided into upstream and downstream segments according the location of the minimum lumen area (MLA) within the plaque. In BLs, compositional analysis showed no differences between the three segments. The necrotic core in contact with the lumen that was located in the downstream segment was significantly larger. While in non-BLs, this was not significantly different between segments. Plaque burden in BLs was 56.60±5.79% vs. 55.50±4.54% in non-BLs, p=0.04. Mean necrotic core area was larger in BLs 0.84±0.55mm2 vs. 0.70±0.49mm2, p=0.048. Mean percentage necrotic core was 15.48±8.02% vs. 14.51±7.64%, p=0.37. There was a trend towards a greater content of necrotic core in contact with the lumen in BLs. The percentage of frames with a major confluent pool of necrotic core in contact with the lumen >10% in BLs was 11.78±17.18 vs. 8.95±17.86 in non-BLs, p=0.065. There was a statistically significant difference in the frequency of IVUS derived thin capped fibroatheromas between bifurcation lesions 20 vs. 13 in non-bifurcation lesions, p=0.03. CONCLUSIONS: Bifurcation lesions appear to have a larger plaque burden with a different plaque composition compared to non-bifurcation lesions. This may partly explain the adverse outcomes seen following treatment of bifurcation lesions in contemporary practice.

Optical coherence tomography (OCT) in secondary revascularisation: stent and graft assessment.

Optical coherence tomography is a recently introduced intracoronary imaging modality with higher spatial resolution than intravascular ultrasound. For this reason, it is increasingly applied to investigate the characteristics of vulnerable atheromatous plaques and the result of stent implantation, struts coverage and restenosis, as well as in procedural decision-making. OCT is also useful in the field of secondary revascularisation, particularly in assessing implanted stents, evaluating relevant technologies like biodegradable stents, and in studying surgical grafts. In this article we perform a review of current developments and evidence in this area.

In vivo assessment of high-risk coronary plaques at bifurcations with combined intravascular ultrasound and optical coherence tomography.

OBJECTIVES: This study sought to evaluate the in vivo frequency and distribution of high-risk plaques (i.e., necrotic core rich) at bifurcations using a combined plaque assessment with intravascular ultrasound-virtual histology (IVUS-VH) and optical coherence tomography (OCT). BACKGROUND: Pathological examinations have shown that atherosclerotic plaque rich in necrotic core is prone to develop at bifurcations. High-risk plaque detection could be improved by the combined use of a technique able to detect necrotic core (IVUS-VH) and a high-resolution technique that allows the measurement of the fibrous cap thickness (OCT). METHODS: From 30 patients imaged with IVUS-VH and OCT, 103 bifurcations were selected. The main branch was analyzed at the proximal rim of the ostium of the side branch, at the in-bifurcation segment and at the distal rim of the ostium of the side branch. Plaques with more than 10% confluent necrotic core by IVUS-VH were selected and classified as fibroatheroma (FA) or thin-cap fibroatheroma (TCFA) depending on the thickness of the fibrous cap by OCT (>65 or < or =65 microm for FA and TCFA, respectively). RESULTS: Twenty-seven FA (26.2%) and 18 TCFA (17.4%) were found out of the 103 lesions studied. Overall the percentage of necrotic core decreases from proximal to distal rim (16.8% vs. 13.5% respectively, p = 0.01), whereas the cap thickness showed an inverse tendency (130 +/- 105 microm vs. 151 +/- 68 microm for proximal and distal rim, respectively, p = 0.05). The thin caps were more often located in the proximal rim (15 of 34, 44.1%), followed by the in-bifurcation segment (14 of 34, 41.2%), and were less frequent in the distal rim (5 of 34, 14.7%). CONCLUSIONS: The proximal rim of the ostium of the side branch has been identified as a region more likely to contain thin fibrous cap and a greater proportion of necrotic core.

Assessment of the absorption process following bioabsorbable everolimus-eluting stent implantation: temporal changes in strain values and tissue composition using intravascular ultrasound radiofrequency data analysis. A substudy of the ABSORB clinical trial.

AIMS: The main objective was to use IVUS-backscatter radiofrequency (IVUS-RF) to assess the degradation of a bioabsorbable stent by measuring serial changes in dense calcium (DC) and necrotic core (NC) as assessed by intravascular ultrasound-Virtual Histology (IVUS-VH) and in the strain as assessed by palpography. METHODS AND RESULTS: In the ABSORB trial, 27 patients treated with a single bioabsorbable everolimus-eluting stent (BVS, Abbott Vascular, Santa Clara, CA, USA) were all imaged with IVUS-RF post-stenting and at 6-month follow-up, and 13 and 12 patients were also investigated pre-stenting with IVUS-VH and palpography respectively. From pre- to post-stenting, with VH (n = 13), there was an increase in mean "DC" (9.8 vs. 25.4%, p = 0.0002) and "NC" (15.5 vs. 30.5%, p = 0.0002). In palpography (n = 12), the mean number of frames with Rotterdam Classification (ROC) III/IV per cm decreased from 1.22 +/- 1.91 to 0.12 +/- 0.31 (p = 0.0781) and the mean cumulative strain values (all frames with ROC I-IV scores) changed from 0.50 +/- 0.27 to 0.20 +/- 0.10% (p = 0.0034). Comparing post-stenting with follow-up (n = 27), VH showed a decrease in "DC" (29.7% vs. 21.1%, p = 0.0001). "NC" also decreased (26.9 vs. 21.5%, p = 0.0027). For palpography (n = 25 patients), an increase in the mean number of frames with ROC III/IV per cm was observed from 0.09 +/- 0.26 to 0.22 +/- 0.36 (p = -0.1563) while the mean cumulative strain values (all frames with ROC I-IV scores) changed from 0.15 +/- 0.10 to 0.26 +/- 0.12% (p < 0.0001). CONCLUSIONS: IVUS-VH changes at 6 months suggest alteration of the BVS with reduction of RF backscattering by polymeric struts. Strained plaques on the palpograms were almost abolished following stent implantation. However, strain values reappeared within 6 months suggesting an increase in endoluminal deformability of the stented vessel.