Morphological features of non-culprit plaques on optical coherence tomography and integrated backscatter intravascular ultrasound in patients with acute coronary syndromes

Intravascular Ultrasound in Vulnerable Plaque and Acute Coronary Syndrome

Vulnerable plaque plays a pivotal role in the pathogenesis of acute coronary syndrome (ACS), being responsible for most ACS. The concept of vulnerable plaque has evolved with advancements in basic and clinical investigations along with developments and rapid expansion of coronary imaging modalities. Intravascular ultrasound (IVUS) is the first widely applied clinical technology with sufficient tissue penetration and enables us to identify vulnerable plaque and comprehensively understand the pathophysiology of ACS. In this review, we summarize current clinical evidence established by IVUS and the recent advancements in our understanding of vulnerable plaque and its role in ACS management.

Radiomics-Based Precision Phenotyping Identifies Unstable Coronary Plaques From Computed Tomography Angiography

OBJECTIVES

The aim of this study was to precisely phenotype culprit and nonculprit lesions in myocardial infarction (MI) and lesions in stable coronary artery disease (CAD) using coronary computed tomography angiography (CTA)-based radiomic analysis.

BACKGROUND

It remains debated whether any single coronary atherosclerotic plaque within the vulnerable patient exhibits unique morphology conferring an increased risk of clinical events.

METHODS

A total of 60 patients with acute MI prospectively underwent coronary CTA before invasive angiography and were matched to 60 patients with stable CAD. For all coronary lesions, high-risk plaque (HRP) characteristics were qualitatively assessed, followed by semiautomated plaque quantification and extraction of 1,103 radiomic features. Machine learning models were built to examine the additive value of radiomic features for discriminating culprit lesions over and above HRP and plaque volumes.

RESULTS

Culprit lesions had higher mean volumes of noncalcified plaque (NCP) and low-density noncalcified plaque (LDNCP) compared with the highest-grade stenosis nonculprits and highest-grade stenosis stable CAD lesions (NCP: 138.1 mm3 vs 110.7 mm3 vs 102.7 mm3; LDNCP: 14.2 mm3 vs 9.8 mm3 vs 8.4 mm3; both Ptrend < 0.01). In multivariable linear regression adjusted for NCP and LDNCP volumes, 14.9% (164 of 1,103) of radiomic features were associated with culprits and 9.7% (107 of 1,103) were associated with the highest-grade stenosis nonculprits (critical P < 0.0007) when compared with highest-grade stenosis stable CAD lesions as reference. Hierarchical clustering of significant radiomic features identified 9 unique data clusters (latent phenotypes): 5 contained radiomic features specific to culprits, 1 contained features specific to highest-grade stenosis nonculprits, and 3 contained features associated with either lesion type. Radiomic features provided incremental value for discriminating culprit lesions when added to a machine learning model containing HRP and plaque volumes (area under the receiver-operating characteristic curve 0.86 vs 0.76; P = 0.004).

CONCLUSIONS

Culprit lesions and highest-grade stenosis nonculprit lesions in MI have distinct radiomic signatures compared with lesions in stable CAD. Within the vulnerable patient may exist individual vulnerable plaques identifiable by coronary CTA-based precision phenotyping.

Identification of anatomic risk factors for acute coronary events by optical coherence tomography in patients with myocardial infarction and residual nonflow limiting lesions: rationale and design of the PECTUS-obs study

INTRODUCTION

In patients with myocardial infarction, the decision to treat a nonculprit lesion is generally based on its physiological significance. However, deferral of revascularisation based on nonischaemic fractional flow reserve (FFR) values in these patients results in less favourable outcomes compared with patients with stable coronary artery disease, potentially caused by vulnerable nonculprit lesions. Intravascular optical coherence tomography (OCT) imaging allows for in vivo morphological assessment of plaque 'vulnerability' and might aid in the detection of FFR-negative lesions at high risk for recurrent events.

METHODS AND ANALYSIS

The PECTUS-obs study is an international multicentre prospective observational study that aims to relate OCT-derived vulnerable plaque characteristics of nonflow limiting, nonculprit lesions to clinical outcome in patients with myocardial infarction. A total of 438 patients presenting with myocardial infarction (ST-elevation myocardial infarction and non-ST-elevation myocardial infarction) will undergo OCT-imaging of any FFR-negative nonculprit lesion for detection of plaque vulnerability. The primary study endpoint is a composite of major adverse cardiovascular events (all-cause mortality, nonfatal myocardial infarction or unplanned revascularisation) at 2-year follow-up. Secondary endpoints will be the same composite at 1-year and 5-year follow-up, target vessel failure, target vessel revascularisation, target lesion failure and target lesion revascularisation.

ETHICS AND DISSEMINATION

This study has been approved by the Medical Ethics Committee of the region Arnhem-Nijmegen. The results of this study will be disseminated in a main paper and additional papers with subgroup analyses.

TRIAL REGISTRATION NUMBER

NCT03857971.

Rationale and design of the MULTISTARS AMI Trial: A randomized comparison of immediate versus staged complete revascularization in patients with ST-segment elevation myocardial infarction and multivessel disease

About half of patients with acute ST-segment elevation myocardial infarction (STEMI) present with multivessel coronary artery disease (MVD). Recent evidence supports complete revascularization in these patients. However, optimal timing of non-culprit lesion revascularization in STEMI patients is unknown because dedicated randomized trials on this topic are lacking. STUDY DESIGN: The MULTISTARS AMI trial is a prospective, international, multicenter, randomized, two-arm, open-label study planning to enroll at least 840 patients. It is designed to investigate whether immediate complete revascularization is non-inferior to staged (within 19-45 days) complete revascularization in patients in stable hemodynamic conditions presenting with STEMI and MVD and undergoing primary percutaneous coronary intervention (PCI). After successful primary PCI of the culprit artery, patients are randomized in a 1:1 ratio to immediate or staged complete revascularization. The primary endpoint is a composite of all-cause death, non-fatal myocardial infarction, ischemia-driven revascularization, hospitalization for heart failure, and stroke at 1 year. CONCLUSIONS: The MULTISTARS AMI trial tests the hypothesis that immediate complete revascularization is non-inferior to staged complete revascularization in stable patients with STEMI and MVD.

Different Microcirculation Response Between Culprit and Non-Culprit Vessels in Patients With Acute Coronary Syndrome

Background

This study investigated whether the microvascular dysfunction differed between culprit and non‐culprit vessels in patients with acute coronary syndrome who underwent percutaneous coronary intervention.

Methods and Results

In 115 prospectively recruited patients, after successful percutaneous coronary intervention, culprit and non‐culprit intracoronary hemodynamic measurements were performed and repeated at 6‐month follow‐up. ¹³N‐ammonia positron emission tomography was performed at 6‐month follow‐up visit to determine absolute myocardial blood flow. The resistance values of each vessel were calculated using the coronary pressure data and the myocardial blood flow values obtained from ¹³N‐ammonia positron emission tomography data. We compared the measurements between culprit and non‐culprit vessels and assessed changes in microvascular dysfunction during the study period. In 334 vessels (115 culprit and 219 non‐culprit), the culprit vessel group showed a lower fractional flow reserve and coronary flow reserve than the non‐culprit vessel group at baseline and 6‐month follow‐up, respectively. The value of index of microcirculatory resistance was different between the 2 groups in the baseline but not at 6‐month follow‐up. The microvascular resistance at rest and hyperemic microvascular resistance were not different between the 2 groups, but resistance to stenosis was higher in the culprit vessel group, under both resting and hyperemic status (P=0.02 and P<0.01, respectively). In the culprit vessel analysis, the fractional flow reserve and index of microcirculatory resistance decreased whereas coronary flow reserve increased (P<0.01 for all) at 6‐month follow‐up. However, there was no change in index of microcirculatory resistance, coronary flow reserve, and fractional flow reserve from baseline to 6‐month follow‐up in the non‐culprit vessel analysis.

Conclusions

The observed microvascular dysfunction in acute coronary syndrome is limited to the culprit vessel territory in the acute phase, which is relatively recovered in the chronic phase and there is no out‐of‐culprit territory involvement.

Registration

URL: https://www.clini​caltr​ials.gov; Unique identifier: NCT04169516.

Should fractional flow reserve follow angiographic visual inspection to guide preventive percutaneous coronary intervention in ST-elevation myocardial infarction?

Aims

We aimed to quantify the effect of preventive percutaneous coronary intervention (PCI to non-infarct arteries) on cardiac death and non-fatal myocardial infarction (MI) in patients with ST-elevation myocardial infarction (STEMI) according to whether the decision to carry out preventive PCI was based on angiographic visual inspection (AVI alone) or AVI plus fractional flow reserve (FFR) if AVI showed significant stenosis (AVI plus FFR).

Methods and results

Randomized trials comparing preventive PCI with no preventive PCI in STEMI without shock were identified by a systematic literature search and categorized according to whether they used AVI alone or AVI plus FFR to select patients for preventive PCI. Random effects meta-analyses and tests of heterogeneity were used to compare the two categories in respect of cardiac death and MI as a combined outcome and individually. Eleven eligible trials were identified. For cardiac death and MI, the relative risk estimates for AVI alone vs. AVI plus FFR were 0.39 (0.25–0.61) and 0.85 (0.57–1.28), respectively (P = 0.01 for difference), for cardiac death, alone the estimates were 0.36 (0.19–0.71) and 0.79 (0.36–1.77), respectively (P = 0.15 for difference), and for MI alone, 0.41 (0.23–0.73) and 0.98 (0.62–1.56), respectively (P = 0.04 for difference).

Conclusion

In preventive PCI among STEMI patients, AVI alone achieves a ∼60% reduction in cardiac death and MI but selecting patients using FFR in AVI positive patients loses much of the benefit. Angiographic visual inspection is best used without FFR in this group of patients.

Culprit-Only or Complete Revascularization for ST-Elevation Myocardial Infarction in Patients with and Without Shock

ST-elevation myocardial infarction (STEMI) patients with multivessel disease and without shock are a common clinical entity, but the best approach to nonculprit vessel lesions remains controversial. In contrast, STEMI patients with shock do not appear to benefit from primary multivessel percutaneous coronary interventions (PCIs) during the index procedure. The optimal treatment strategy in a given STEMI patient involves an individualized approach, incorporating clinical, hemodynamic, and angiographic/imaging parameters. Patients with STEMI and cardiogenic shock may benefit from therapies other than PCI, such as mechanical cardiovascular support.

Morphological Features and Plaque Composition in Culprit Atheromatous Plaques of Patients with Acute Coronary Syndromes

Background: The independent role of each plaque feature in relation to plaque vulnerability is still the subject of ongoing research. This study aimed to compare the morphologic characteristics of vulnerable atheromatous coronary plaques with the ones of stable, non-vulnerable plaques, and in plaques with different locations in the coronary tree, in order to identify the most relevant imaging-based biomarkers associated with coronary plaque vulnerability.

Material and methods: This was a prospective observational, non-randomized study that included 50 patients with unstable angina who underwent computed tomography angiography for assessment of the entire coronary artery tree followed by complex morphologic analysis of all lesions, divided into two groups: group 1 – 25 patients with vulnerable plaque (VP) and group 2 – 25 age- and gender-matched patients with non-vulnerable plaque (NVP).

Results: Lesions with a stenosis degree >70% were significantly longer than those with a stenosis degree <70% (8.27 ± 2.74 mm vs. 5.56 ± 4.11 mm, p = 0.04). VP presented significantly higher values of plaque thickness (p = 0.0005), plaque burden (p = 0.0004), and higher total plaque volume (p = 0.0005) than NVP. The remodeling index was not significantly different between the groups (p = 0.6), but the eccentricity index was (0.24 ± 0.14 compared to 0.14 ± 0.17, p = 0.023). Linear regression analysis revealed a significant correlation between plaque burden and plaque components in VP (r = 0.76, p <0.0001 for necrotic core; r = 0.62, p = 0.0008 for fibro-fatty tissue; and r = 0.5, p = 0.01 for fibrotic tissue volume). Culprit plaques located in the right coronary artery presented significantly larger plaque burden volumes (91.17 ± 4.88 mm3 vs. 83.35 ± 8.47 mm3, p = 0.04), larger volumes of necrotic core (82.03 ± 47.85 mm3 vs. 45.84 ± 43.72 mm3, p = 0.02) and fibrofatty tissue (53.23 ± 31.92 mm3 vs. 23.76 ± 20.90 mm3, p = 0.02) than the ones situated in the left coronary artery.

Conclusions: VPs from the culprit lesions exhibit a different phenotype than non-vulnerable ones, and vulnerability features are present in a significantly larger extent in VPs from the right coronary artery as compared to those from the left coronary artery.

Impact of the triglyceride level on coronary plaque components in female patients with coronary artery disease treated with statins

Several studies have reported that elevated triglyceride (TG) levels may be more strongly associated with an increased risk of coronary artery disease (CAD) in females than in males. We examined gender differences in the relationship between TG levels and coronary atherosclerosis using integrated backscatter intravascular ultrasound (IB IVUS) in CAD patients treated with statins. Three hundred seventy-eight CAD patients (105 females and 273 males) who underwent percutaneous coronary intervention using IB IVUS, and who were already receiving statin treatment, were included. Gray-scale and IB IVUS examinations were performed for the non-culprit segment of a coronary artery and fasting serum TG concentrations were measured. We found that TG levels were significantly correlated with increased lipid (r = 0.40, p < 0.001) and decreased fibrous (r = - 0.37, p < 0.001) plaque components in females, but not in males. Low-density lipoprotein cholesterol and high-density lipoprotein cholesterol levels were not related to either the gray-scale or IB IVUS parameters in both genders. After adjustment for conventional coronary risk factors by a multivariate stepwise regression analysis, higher TG levels in females were independently associated with increased lipid (β = 0.31, p< 0.001) contents in coronary plaques. In conclusion, among CAD patients treated with statins, TG levels were associated with lipid-rich coronary plaques in females, but not in males. TG levels may be more important indicators of residual risk after statin treatment in females than in males.

Early Detection and Treatment of the Vulnerable Coronary Plaque

Early identification and treatment of the vulnerable plaque, that is, a coronary artery lesion with a high likelihood of rupture leading to an acute coronary syndrome, have gained great interest in the cardiovascular research field. Postmortem studies have identified clear morphological characteristics associated with plaque rupture. Recent advances in invasive and noninvasive coronary imaging techniques have empowered the clinician to identify suspected vulnerable plaques in vivo and paved the way for the evaluation of therapeutic agents targeted at reducing plaque vulnerability. Local treatment of vulnerable plaques by percutaneous coronary intervention and systemic treatment with anti-inflammatory and low-density lipoprotein–lowering drugs are currently being investigated in large randomized clinical trials to assess their therapeutic potential for reducing adverse coronary events. Results from these studies may enable a more patient-tailored strategy for the treatment of coronary artery disease.

Assessment of Coronary Plaque Vulnerability in Acute Coronary Syndromes using Optical Coherence Tomography and Intravascular Ultrasound. A Systematic Review

The aim of this systematic review was to analyze studies characterizing vulnerable coronary plaques using optical coherence tomography (OCT) and intravascular ultrasound (IVUS), in order to identify the most efficient invasive technique permitting plaque characterization in patients with acute myocardial infarction.

Method: A total number of 432 studies were identified, 420 through database searching and 12 through manual searching. Eight duplicate studies were removed, leaving a total number of 424 studies to be screened. Twenty-six studies only available in Abstract-only form were excluded, resulting in 398 studies checked for eligibility. Eleven studies fulfilled the eligibility criteria and were included in this systematic analysis. Plaque vulnerability was investigated in plaques with thin cap fibroatheroma (TCFA) versus those with thick cap fibroatheroma, in ruptured coronary plaques versus non-ruptured coronary plaques, in culprit versus non-culprit lesions and in lipid-rich versus non-lipid-rich plaques.

Results: A total of 1,568 coronary plaques in 1,225 patients with acute coronary syndromes (ACS) who underwent both IVUS and OCT for analysis of plaque features were included in the final analysis. The review identified the following IVUS-derived features as significantly correlated with plaque vulnerability: plaque burden (p <0.001), remodeling index (p <0.001), external elastic membrane cross-sectional area (p <0.001), and the amount of necrotic core (p <0.001), while OCT-derived features characterizing unstable plaque were TCFA (p <0.001), lipid arch (p <0.001), accumulation of macrophages (p = 0.03), and presence of intracoronary thrombus (p <0.001).

Conclusion: Both IVUS and OCT are invasive imaging techniques able to provide relevant information on the vulnerability of coronary atheromatous plaques, identifying, as they do, various plaque features significantly associated with unstable plaques. Information provided by the two techniques is complementary, and both methods can serve as a useful clinical diagnostic tool, especially in cases of ACS patients undergoing a revascularization procedure.

Clinical Characteristics and Prognosis of Peri-strut Low-intensity Area Detected by Optical Coherence Tomography

Background:

Peri-strut low-intensity area (PLIA) is a typical image pattern of neointima detected by optical coherence tomography (OCT) after stent implantation. However, few studies evaluated the predictors and prognosis of the PLIA; therefore, we aimed to explore the genesis and prognosis of PLIA detected by OCT in this study.

Methods:

Patients presenting neointimal hyperplasia documented by OCT reexamination after percutaneous coronary intervention were prospectively included from 2009 to 2011. Peri-strut intensity was analyzed and classified into two patterns: Low-intensity and high-intensity. Clinical characteristics were analyzed to assess their contribution to peri-strut intensity patterns. Follow-up were performed in patients who did not receive revascularization during OCT reexamination, and the prognosis of the patients was evaluated.

Results:

There were 128 patients underwent OCT reexamination after stent implantation included in the study. PLIA was detected in 22 (17.2%) patients. The incidence of PLIA was positively correlated with serum triglyceride (odds ratio [OR]: 2.11, 95% confidence interval [CI]: 1.14–3.90, P = 0.017), low-density lipoprotein (OR: 2.61, 95% CI: 1.22–5.66, P = 0.015), history of cerebrovascular disease (OR: 101.11, 95% CI: 6.54–1562.13, P < 0.001), and initial clinical presentation of acute coronary syndrome (ACS, OR: 18.77, 95% CI: 2.73–128.83, P = 0.003) while negatively correlated with stent implantation time (OR: 0.57, 95% CI: 0.33–0.98, P = 0.043). The median follow-up was longer than 3.8 years. Major adverse cardiovascular events (MACEs) occurred in 7 (7.3%) patients while showed no correlation with PLIA. A total of 17 (17.7%) patients experienced unstable angina (UA) and showed significant correlation with PLIA (hazard ratio: 6.16, 95% CI: 1.25–30.33, P = 0.025).

Conclusions:

PLIA detected by OCT was positively correlated with higher serum lipid level, history of cerebrovascular disease and initial presentation of ACS, and negatively correlated with stent implantation time. Patients with PLIA were more likely to have UA than those with high-intensity while no significant difference was found in MACEs.

Glycemic Variability on Continuous Glucose Monitoring System Correlates With Non-Culprit Vessel Coronary Plaque Vulnerability in Patients With First-Episode Acute Coronary Syndrome - Optical Coherence Tomography Study

BACKGROUND

Glycemic variability (GV) is associated with coronary plaque rupture at the culprit lesion in acute myocardial infarction (AMI). The present study determined the relationship between GV and coronary plaque vulnerability in the non-culprit vessel.

METHODS AND RESULTS

The present prospective study involved 46 patients with first-episode acute coronary syndrome (ACS) who underwent optical coherence tomography in the non-culprit vessel. The relationship between GV, assessed with continuous glucose monitoring system, and the presence of thin-cap fibroatheroma (TCFA) at the non-culprit plaque with mild-to-moderate stenosis in the non-culprit vessel, was assessed. GV was quantified using mean amplitude of glycemic excursion (MAGE). Patients were divided into tertiles according to MAGE. TCFA was observed in 13 (28%) of the 46 patients. Fibrous cap thickness was thinner (MAGE tertiles: high, 80±40 µm; intermediate, 152±122 µm; low, 155±102 µm; P=0.01), and TCFA was more common (MAGE tertiles: high, 50%; intermediate, 27%; low, 7%; P=0.03) in patients with high MAGE. On multivariate logistic analysis high MAGE was the only significant determinant of TCFA, independent of coronary risk factors (OR, 5.000; P=0.021), homeostasis model assessment of insulin resistance, and hemoglobin A1c(OR, 5.674; P=0.018).

CONCLUSIONS

High MAGE measured early after the onset of first-episode ACS correlated with thinner fibrous cap thickness and higher prevalence of TCFA at the non-culprit plaque in the non-culprit vessel.