Intravascular ultrasound analysis of infarct-related and non-infarct-related arteries in patients who presented with an acute myocardial infarction

Clinical outcomes of acute myocardial infarction arising from non-lipid-rich plaque determined by NIRS-IVUS

Acute myocardial infarction (AMI) can rarely arise from non-lipid-rich coronary plaques. This study sought to compare the clinical outcomes after percutaneous coronary intervention (PCI) between AMI showing maximum lipid-core burden index in 4 mm (maxLCBI_4mm) < 400 and ≥ 400 in the infarct-related lesions assessed by near-infrared spectroscopy-intravascular ultrasound (NIRS-IVUS). We investigated 426 AMI patients who underwent NIRS-IVUS in the infarct-related lesions before PCI. Major adverse cardiovascular events (MACE) were defined as the composite of cardiac death, non-fatal MI, clinically driven target lesion revascularization (TLR), clinically driven non-TLR, and congestive heart failure requiring hospitalization. 107 (25%) patients had infarct-related lesions of maxLCBI_4mm < 400, and 319 (75%) patients had those of maxLCBI_4mm ≥ 400. The maxLCBI_4mm < 400 group had a younger median age at onset (68 years [IQR: 57-78 years] vs. 73 years [IQR: 64-80 years], P = 0.007), less frequent multivessel disease (39% vs. 51%, P = 0.029), less frequent TIMI flow grade 0 or 1 before PCI (62% vs. 75%, P = 0.007), and less frequent no-reflow immediately after PCI (5% vs. 11%, P = 0.039). During a median follow-up period of 31 months [IQR: 19-48 months], the frequency of MACE was significantly lower in the maxLCBI_4mm < 400 group compared with the maxLCBI_4mm ≥ 400 group (4.7% vs. 17.2%, P = 0.001). MaxLCBI_4mm < 400 was an independent predictor of MACE-free survival at multivariable analysis (hazard ratio: 0.36 [confidence interval: 0.13-0.98], P = 0.046). MaxLCBI_4mm < 400 measured by NIRS in the infract-related lesions before PCI was associated with better long-term clinical outcomes in AMI patients.

Utility of optical coherence tomography in acute coronary syndromes

Studies utilizing intravascular imaging have replicated the findings of histopathological studies, identifying the most common substrates for acute coronary syndromes (ACS) as plaque rupture, erosion, and calcified nodule, with spontaneous coronary artery dissection, coronary artery spasm, and coronary embolism constituting the less common etiologies. The purpose of this review is to summarize the data from clinical studies that have used high-resolution intravascular optical coherence tomography (OCT) to assess culprit plaque morphology in ACS. In addition, we discuss the utility of intravascular OCT for effective treatment of patients presenting with ACS, including the possibility of culprit lesion-based treatment by percutaneous coronary intervention.

Evolving concepts of the vulnerable atherosclerotic plaque and the vulnerable patient: implications for patient care and future research

Understanding the natural history of coronary artery atherosclerosis is necessary to determine prognosis and prescribe effective therapies. Traditional management of coronary artery disease has focused on the treatment of flow-limiting anatomical obstructions that lead to ischaemia. In most scenarios, revascularization of these atherosclerotic plaques has not substantially improved freedom from death or myocardial infarction, questioning the utility of contemporary revascularization strategies to improve prognosis. Advances in non-invasive and invasive imaging techniques have helped to identify the characteristics of obstructive and non-obstructive plaques that are precursors for plaque progression and future acute coronary syndromes as well as cardiac death. These 'vulnerable plaques' develop as a consequence of systemic inflammation and are prone to inducing thrombosis. Vulnerable plaques most commonly have a large plaque burden with a well-formed necrotic core and thin fibrous cap and are metabolically active. Perivascular adipose tissue might, in some patients, be used as a surrogate for coronary inflammation and predict future risk of adverse cardiac events. Vulnerable plaques can be identified in their quiescent state, offering the potential for therapeutic passivation. In this Review, we describe the biological and compositional features of vulnerable plaques, the non-invasive and invasive diagnostic modalities to characterize vulnerable plaques, the prognostic utility of identifying vulnerable plaques, and the future studies needed to explore the value of intensified pharmacological and focal treatments of vulnerable plaques.

Staged revascularization vs. culprit-only percutaneous coronary intervention for multivessel disease in elderly patients with ST-segment elevation myocardial infarction

Backgroundand objective

Studies have highlighted the significant role of staged percutaneous coronary intervention (PCI) for a multivessel disease (MVD) among patients with ST-elevation myocardial infarction (STEMI). However, the relative benefit of staged vs. culprit-only PCI for MVD in elderly patients with STEMI remains undetermined. Thus, the present study compared the clinical outcomes of staged and culprit-only PCI in this cohort.

Methods

From January 2014 to September 2019, 617 patients aged ≥65 years with STEMI and MVD who underwent primary PCI of the culprit vessels within 12 h of symptom onset were enrolled. They were then categorized into the staged and culprit-only PCI groups according to intervention strategy. Propensity score matching (PSM) was conducted to adjust for confounding factors between groups. The primary end point was major adverse cardiac and cerebrovascular events (MACCE), a composite of all-cause death, cardiac death, recurrent myocardial infarction (MI), stroke, and ischemia-driven revascularization.

Results

During a mean follow-up of 56 months, 209 patients experienced MACCE and 119 died. Staged revascularization was associated with a lower risk of MACCE, all-cause death, and cardiac death than culprit-only PCI in both overall patients and the PSM cohorts. In contrast, there was no significant difference in stroke or ischemia-driven revascularization. Moreover, on multivariate Cox regression analysis, staged PCI was a significant predictor of a lower incidence of MACCE and all-cause death.

Conclusion

In elderly patients with STEMI and MVD, staged PCI is superior to culprit-only PCI.

Role of Intracoronary Imaging in Acute Coronary Syndromes

Intravascular imaging with optical coherence tomography (OCT) and intravascular ultrasound provides superior visualization of the culprit plaques for acute coronary syndromes (ACS) compared with coronary angiography. Combined with angiography, intravascular imaging can be used to instigate ‘precision therapy’ for ACS. Post-mortem histopathology identified atherothrombosis at the exposed surface of a ruptured fibrous cap as the main cause of ACS. Further histopathological studies identified intact fibrous caps and calcified nodules as other culprit lesions for ACS. These plaque types were subsequently also identified on intravascular imaging, particularly with the high-resolution OCT. The less-common non-atherothrombotic causes of ACS are coronary artery spasm, coronary artery dissection, and coronary embolism. In this review, the authors provide an overview of clinical studies using intravascular imaging with OCT in the diagnosis and management of ACS.

Intravascular ultrasound insights into the unstable features of the coronary atherosclerotic plaques: A systematic review and meta-analysis

BACKGROUND

There is a lack of a comprehensive picture of plaque geometry and composition of unstable atherosclerotic lesions as observed with intravascular ultrasound techniques. We analysed through a systematic review with meta-analysis 39 characteristics of atherosclerotic plaques in three scenarios involving culprit and non-culprit lesions from acute coronary syndromes vs stable angina pectoris patients, and culprit vs non-culprit lesions in acute coronary syndromes patients.

METHODS

A systematic search of PubMed and EMBASE, from inception to April 2020 was performed. The combined odds ratios or mean differences of all IVUS characteristics were calculated with random-effects models.

RESULTS

Twenty-eight studies involving 5434 subjects, and 5618 lesions were included. Culprit lesions in acute coronary syndromes have larger plaque areas and remodeling indexes (MD = 0.13 [0.08; 0.17], p < 0.001) and contained larger necrotic cores (MD = 0.67 (95% CI 0.19;1.15), p = 0.006) that stable angina culprit lesions. In acute patients, culprit plaques were also more remodeled, had larger necrotic cores and had more frequently a Thin-Cap Fibroatheroma morphology (OR = 1.79 (95% CI 1.21; 2.65), p = 0.004) than non-culprit lesions. Non-culprit lesions in acute syndromes were more often ruptured (OR = 2.25 (95% CI:1.05; 4.82), p = 0.037) or Thin-Cap Fibroatheromas than in stable angina.

CONCLUSION

Culprit lesions from acute coronary patients are larger, more positively remodeled and contained more lipids as compared to stable angina lesions or non-culprit in acute patients. Non culprit lesions are also more often complicated or vulnerable in acute than stable patients.

Optical Coherence Tomography in Acute Coronary Syndromes

Advances in intravascular imaging have enabled assessment of the underlying plaque morphology in acute coronary syndromes, which allows for the initiation of individualized therapy. The atherothrombotic substrates for acute coronary syndromes consist of plaque rupture, erosion, and calcified nodule, whereas spontaneous coronary artery dissection, coronary artery spasm, and coronary embolism constitute rarer nonatherothrombotic etiologies. This review provides a brief overview of the data from clinical studies that have used intravascular optical coherence tomography to assess the culprit plaque morphology. We discuss the usefulness of intravascular imaging for effective treatment of patients presenting with acute coronary syndromes by percutaneous coronary intervention.

Lesion characteristics and prognosis of acute coronary syndrome without angiographically significant coronary artery stenosis

AIMS

While patients with acute coronary syndrome (ACS) presenting with non-obstructive coronary artery disease (CAD) are at high risk for cardiovascular mortality and morbidity, detailed lesion characteristics are unclear. The aim of this study was to investigate the lesion characteristics and prognosis of ACS with non-obstructive CAD.

METHODS AND RESULTS

This study consisted of 82 consecutive ACS patients without obstructive CAD who underwent optical coherence tomography (OCT). Based on the presence of high-risk lesions (HL) in the culprit artery, we classified the patients into two groups: HL group and non-high-risk lesions (NHL) group. A systematic clinical follow-up was performed at our outpatient clinic for up to 24 months. Our endpoint was recurrence of ACS with obstructive CAD. OCT revealed that 42 (51.2%) of 82 patients had hidden HL in the culprit artery, including ruptured plaque (15.9%), calcified nodule (11.0%), spontaneous coronary artery dissection (8.5%), lone thrombus (8.5%), thin-cap fibroatheroma (6.1%), and plaque erosion (1.2%). During angiography, 5 (11.9%) HL patients complained of chest pain without ST elevation. Patients in the HL group had poorer prognoses than those in the other groups (P = 0.040).

CONCLUSION

Hidden high-risk lesions accompany ACS patients without obstructive CAD, resulting in poorer outcomes. Vascular injury itself might provoke acute chest pain.

Pitavastatin Combined with Ezetimibe Treatment was an Effective Approach to Non-IRA Lesion of ST-segment Elevation Myocardial Infarction Patients with Primary Percutaneous Coronary Intervention

OBJECTIVE

ST-Segment Elevation Myocardial Infarction (STEMI) patients with the multivessel disease have distinctive plaque characteristics in non-IRA lesions. Intensive statin therapy was a potential approach to treat STEMI patients with the non-IRA disease. However, there is still poor evidence about the therapeutic effect. In this study, we have evaluated the detailed therapeutic effect of statin plus ezetimibe intensive therapy.

METHODS

For STEMI patients with non-IRA disease undergoing primary Percutaneous Coronary Intervention (PCI), 183 control STEMI patients without non-IRA disease undergoing primary PCI, and 200 STEMI patients with non-IRA disease undergoing primary PCI were introduced into this study. 200 STEMI patients with non-IRA disease undergoing primary PCI were divided into Normal group, Intensive group, Normal & Combined group, and Intensive & Combined group. The baseline information for each participant was recorded. Meanwhile, the physiological and biochemical indicators of each member with different treatments were collected after one-year follow-up.

RESULTS

For STEMI patients with non-IRA disease undergoing primary PCI, no differences could be detected in multiple indexes such as OCT examination results, age, stroke, etc. However, diabetes mellitus, smoking, and coronary Gensini score were different between different groups (P<0.05). After one year follow-up, cholesterol, low-density lipoprotein, coronary Gensini score, thin-cap fibroatheroma, length of non-infarcted arterial lesions, non-infarct artery lesion range, myocardial infarction again, and revascularization again were significantly different between different groups (P<0.05).

CONCLUSION

The results mentioned above suggested that pitavastatin combined with ezetimibe was an effective approach for STEMI patients with non-IRA disease undergoing primary PCI. The results obtained in this study have provided a novel method for the treatment of STEMI patients with non-IRA disease undergoing primary PCI.

Mechanically Rotating Intravascular Ultrasound (IVUS) Transducer: A Review

Intravascular ultrasound (IVUS) is a valuable imaging modality for the diagnosis of atherosclerosis. It provides useful clinical information, such as lumen size, vessel wall thickness, and plaque composition, by providing a cross-sectional vascular image. For several decades, IVUS has made remarkable progress in improving the accuracy of diagnosing cardiovascular disease that remains the leading cause of death globally. As the quality of IVUS images mainly depends on the performance of the IVUS transducer, various IVUS transducers have been developed. Therefore, in this review, recently developed mechanically rotating IVUS transducers, especially ones exploiting piezoelectric ceramics or single crystals, are discussed. In addition, this review addresses the history and technical challenges in the development of IVUS transducers and the prospects of next-generation IVUS transducers.

Atherothrombosis in Acute Coronary Syndromes-From Mechanistic Insights to Targeted Therapies

The atherothrombotic substrates for acute coronary syndromes (ACS) consist of plaque ruptures, erosions and calcified nodules, while the non-atherothrombotic etiologies, such as spontaneous coronary artery dissection, coronary artery spasm and coronary embolism are the rarer causes of ACS. The purpose of this comprehensive review is to (1) summarize the histopathologic insights into the atherothrombotic plaque subtypes in acute ACS from postmortem studies; (2) provide a brief overview of atherogenesis, while mainly focusing on the events that lead to plaque destabilization and disruption; (3) summarize mechanistic data from clinical studies that have used intravascular imaging, including high-resolution optical coherence tomography, to assess culprit plaque morphology and its underlying pathobiology, especially the newly described role of innate and adaptive immunity in ACS secondary to plaque erosion; (4) discuss the utility of intravascular imaging for effective treatment of patients presenting with ACS by percutaneous coronary intervention; and (5) discuss the opportunities that these mechanistic and imaging insights may provide for more individualized treatment of patients with ACS.

Culprit lesion detection in patients presenting with non-ST elevation acute coronary syndrome and multivessel disease

BACKGROUND/PURPOSE

Identification of the culprit lesion in patients with non-ST elevation acute coronary syndrome (NSTE-ACS) allows appropriate coronary revascularization but may be unclear in patients with multivessel coronary disease (MVD). Therefore, we investigated the rate of culprit lesion identification during coronary angiography in NSTE-ACS and multivessel disease.

METHODS/MATERIALS

Consecutive patients presenting with NSTE-ACS and MVD, between January 2012 and December 2016 were evaluated. Coronary angiograms, intravascular imaging, and ECGs were analyzed for culprit lesion identification. Long-term clinical outcomes in terms of major adverse cardiac events (MACE) and mortality were reported in patients with or without culprit identification.

RESULTS

A total of 1107 patients with NSTE-ACS and MVD were included in the analysis, 310 (28.0%) with unstable angina and 797 (72.0%) with non-ST elevation myocardial infarction. The culprit lesion was angiographically identified in 952 (86.0%) patients, while no clear culprit lesion was found in 155 (14.0%) patients. ECG analysis allowed to predict the location of the culprit vessel with low sensitivity (range 28.4%-36.7%) and high specificity (range 90.6%-96.5%). Higher lesion complexity was associated with inability to identify the culprit. Intravascular imaging was applied in 55 patients and helped to identify the culprit lesion in 53 patients (96.4%). There was no difference in all-cause mortality (21.4% vs. 25.8%, p = 0.24) and MACE (39.2% vs. 47.6%, p = 0.07) between the cohorts with or without culprit lesion identification by angiography.

CONCLUSIONS

The culprit lesion appeared unclear by coronary angiography in >10% of patients with NSTE-ACS and MVD. Complementary invasive imaging substantially enhanced the diagnostic accuracy of culprit lesion detection.

Three-Dimensional Fluid Dynamical Features of Coronary Plaque Rupture Provoking Acute Coronary Syndrome

AIM

Coronary plaque rupture is the main cause of acute coronary syndrome (ACS), but the role of blood flow features around plaque rupture for ACS is still unknown. The present study aimed to assess the relationship between the geometric configuration of ruptured plaque and ACS occurrence using computational fluid dynamics (CFD) by moving particle method in patients with coronary artery disease.

METHODS

In this study, 45 patients with coronary artery disease who underwent three-dimensional intravascular ultrasound (IVUS) and had a coronary ruptured plaque (24 plaques with provoked ACS, 21 without) were included. To compare the difference in blood flow profile around ruptured plaque between the patients with and without ACS, the IVUS images were analyzed via the novel CFD analysis.

RESULTS

There were no significant differences in localized flow profile around ruptured plaque between the two groups when the initial particle velocity was 10.0 cm/s corresponded to a higher coronary flow velocity at ventricular diastole. However, when it was 1.0 cm/s corresponded to lower coronary flow velocity at ventricular systole, particles with lower velocity (0 ≤ V ≤ 5 cm/s) were more prevalent around ACS-PR (p=0.035), whereas particles with higher velocity (10 ≤ V ≤ 20 cm/s) were more often detected in silent plaque ruptures (p=0.018).

CONCLUSIONS

Three-dimensional IVUS revealed that coronary plaque rupture was a complex one with a wide variety of its stereoscopic configuration, leading to various patterns of the local coronary flow profile. A novel CFD analysis suggested that the local flow was more stagnant around ACS-provoked ruptures than in silent ones.

Relationship between arterial remodelling and serial changes in coronary atherosclerosis by intravascular ultrasound: an analysis of the IBIS-4 study

AIMS

Arterial remodelling is an important determinant of coronary atherosclerosis. Assessment of the remodelling index, comparing a lesion to a local reference site, is a suboptimal correlate of serial vascular changes. We assessed a novel approach which, unlike the local-reference approach, uses the entire artery's global remodelling as reference.

METHODS AND RESULTS

Serial (baseline and 13 months) intravascular ultrasound was performed in 146 non-infarct-related arteries of 82 patients treated with high-intensity statin. Arteries were divided into 3-mm segments (n = 1479), and focal remodelling was characterized in individual segments at both timepoints applying the global arterial reference approach. First, we compared preceding vascular changes in relation to follow-up remodelling. Second, we examined whether baseline remodelling predicts subsequent plaque progression/regression. At follow-up, segments with constrictive vs. compensatory or expansive remodelling had greater preceding reduction of vessel area (-0.67 vs. -0.38 vs. -0.002 mm2; P < 0.001) and lumen area (-0.82 vs. -0.09 vs. 0.40 mm2; P < 0.001). Overall, we found significant regression in percent atheroma volume (PAV) [-0.80% (-1.41 to -0.19)]. Segments with constrictive remodelling at baseline had greater subsequent PAV regression vs. modest regression in the compensatory, and PAV progression in the expansive remodelling group (-6.14% vs. -0.71% vs. 2.26%; P < 0.001). Lesion-level analyses (n = 118) showed no differences when remodelling was defined by the local reference approach at baseline or follow-up.

CONCLUSION

Remodelling assessment using a global arterial reference approach, but not the commonly used, local reference site approach, correlated reasonably well with serial changes in arterial dimensions and identified arterial segments with subsequent PAV progression despite intensive statin treatment and overall atheroma regression.

High Dietary Inflammatory Index Is Associated With Increased Plaque Vulnerability of Carotid in Patients With Ischemic Stroke

BACKGROUND AND PURPOSE

Long-term dietary patterns can influence the intensity of systemic inflammation and, therefore, the development of atherosclerosis. This study aimed to evaluate the association between dietary inflammatory index (DII) and vulnerability characteristics of carotid atherosclerotic plaques in patients with ischemic stroke.

METHODS

Patients with ischemic stroke within 7 days of onset were enrolled. DII was calculated from 32 food components with the help of a food frequency questionnaire. Vulnerable plaque was defined as presence of artery positive remodeling (remodeling index >1.1) and low CT attenuation plaques (<35 HU) on carotid arteries by computed tomography angiography.

RESULTS

Of the 398 enrolled patients, 144 (36.2%) were detected with vulnerable plaque. Their DII ranged from -4.58 to 4.18. Patients with vulnerable plaques consumed less nutrients with anti-inflammatory properties, less fruits and vegetables (85.6±64.3 versus 94.6±74.4 g/d, P=0.027), and less nuts (5.66±7.14 versus 8.84±15.9 g/d, P=0.024) than patients without vulnerable plaques. Patients with vulnerable plaque had higher DII than patients without vulnerable plaque (-0.26±1.54 versus -0.64±1.53, P=0.018). Logistic regression analysis revealed that DII was associated with vulnerable plaques after adjusted for major confounding factors (odds ratio=1.307; 95% CI, 1.113-1.533).

CONCLUSIONS

DII is associated with the vulnerability of carotid plaques in patients with ischemic stroke. Considering a possible causal relationship, the mechanisms underlying the association between diet and atherosclerosis warrant further study.

Comparison of Intravascular Ultrasound Virtual Histology Parameters in Diabetes versus Non-Diabetes with Acute Coronary Syndrome

INTRODUCTION

The progression and pattern of coronary atherosclerosis in diabetes mellitus (DM) is different from non-DM, leading to a higher rate of vascular complications in DM.

OBJECTIVE

This study aims to assess and compare the high-risk plaque characteristics in the culprit artery of DM and non-DM patients with acute coronary syndrome (ACS) using virtual histology intravascular ultrasound (VH-IVUS).

METHODS

A total of 158 ACS patients were included, 63 of whom were known to have DM. IVUS analysis was done in the de novo target vessel and culprit lesion for which percutaneous coronary intervention was planned. Culprit lesions with a visual-estimate angiographic stenosis of <70% were excluded.

RESULTS

The mean age of patients was 52.4 ± 11.6 years. The study group comprised 82% men, 31% with hypertension, and 39.87% with DM. No significant difference was observed between the DM and non-DM groups in relation to quantitative IVUS parameters like lesion length, minimal lumen area, and plaque area. However, there was a significant difference in VH-IVUS parameters like higher necrotic core and dense calcium in the DM patients than in the non-DM patients (p < 0.01). The occurrence of VH-derived thin-cap fibroatheroma (VH-TCFA) in the culprit vessel was significantly higher in the DM group than in the non-DM group (25.3 vs. 5.2%; p < 0.01). Positive vessel-wall remodeling was noted in both groups without any significant difference (p = 0.74).

CONCLUSION

The DM patients had high-risk plaque composition features like a higher necrotic core, which is a marker of plaque vulnerability. Thus, aggressive medical therapy targeting vascular inflammation using high-dose statins would help in the stabilization of unstable plaque morphology and the reduction of major cardiovascular events.

Improved crossability with novel cutting balloon versus scoring balloon in the treatment of calcified lesion

Cutting balloons and scoring balloons are commonly used for the preparation of calcified lesion. However, problems with crossability occasionally limit the use of cutting balloons. We prospectively selected 173 calcified lesions treated using a novel cutting balloon (Wolverine™, C group). As control, we retrospectively analyzed 146 calcified lesions treated using a scoring balloon (Lacrosse NSE ALPHA™, S group). Either intravascular ultrasound (IVUS) or optical coherence tomography (OCT) was used by the operator's discretion. The primary outcome was delivery success, which was defined as successful passage to the target lesion immediately after IVUS or OCT evaluation. The secondary outcome was acute cross-sectional area (CSA) gain, which was defined as post-interventional minimum stent area minus pre-procedural minimum lumen area. A multivariate analysis evaluated the independent predictors for delivery success. The delivery success rate was significantly higher in the C group versus the S group (90.8% versus 79.5%, P = 0.006). However, the acute CSA gain was similar between the two groups (IVUS: 3.2 ± 1.8 mm² versus 3.4 ± 1.9 mm², P = 0.53; OCT: 3.6 ± 1.4 mm² versus 4.1 ± 1.9 mm², P = 0.11). Usage of cutting balloon was an independent predictor for delivery success even after the adjustment for the patient and lesion characteristics [odds ratio (OR): 2.72 (95% confidence interval 1.38-5.33), P = 0.004] as well as the procedural characteristics [OR: 2.34 (1.15-4.86), P = 0.018]. Novel cutting balloons demonstrated better crossability and similar acute CSA gain compared with scoring balloons in calcified lesion.

Association of slow flow with clinical factors in intravascular ultrasound-guided percutaneous coronary intervention for patients with left main trunk-acute myocardial infarction

BACKGROUND

Slow flow can be fatal in primary percutaneous coronary interventions for left main trunk (LMT)-acute myocardial infarction (AMI), however, risk factors for slow flow in LMT-AMI have not been well investigated. Intravascular ultrasound (IVUS) may help to stratify the high-risk lesion for slow flow in LMT-AMI.

METHODS

A total of 51 LMT-AMI were included as the study population, and were divided into the slow-flow group (n=22) and the non-slow-flow group (n=29). Slow flow was defined as either transient or persistent Thrombolysis in Myocardial Infarction (TIMI) flow grade ≤2.

RESULTS

The incidence of in-hospital death was higher in the slow-flow group (27.3%) than the non-slow-flow group (10.3%) without reaching statistical significance (p=0.116). Although the reference diameter measured by angiography was not different between the two groups, the vessel diameter measured by IVUS was significantly longer in the slow-flow group (5.22±0.69mm) than in the non-slow-flow group (4.50±0.47mm) (p<0.001). Multivariate logistic regression analyses revealed that the vessel diameter by IVUS (OR 27.487, 95%CI 3.975-190.062, p=0.001) and the vessel area by IVUS (OR 1.458, 95%CI 1.160-1.832, p=0.001) were significantly associated with slow flow.

CONCLUSIONS

In LMT-AMI, the vessel diameter measured by IVUS was closely associated with slow flow, while the reference diameter measured by angiography was not associated with slow flow. IVUS would be important to find high-risk features for slow flow in LMT-AMI.

Gender differences in plaque characteristics of nonculprit lesions in patients with coronary artery disease

BACKGROUND

Although numerous reports suggest sex-related differences in atherosclerosis, limited data describing gender-associated differences in plaque morphology and composition are currently available. The aim of the present study was to compare coronary nonculprit plaque characteristics in women and men with coronary artery disease (CAD) by optical coherence tomography (OCT).

METHODS

This was a retrospective study. A total of 187 nonculprit plaques were identified in 103 patients with CAD who underwent OCT imaging of all 3 coronary arteries. These patients included 77 (74.8%) men and 26 (25.2%) women.

RESULTS

Female patients were significantly older than males (mean age, 70.8 ± 7.3 vs 60.8 ± 9.8 years; P < 0.001) and less likely to be current smokers (P = 0.007). OCT analysis included the presence of lipid-rich plaque, maximum lipid arc, lipid-core length, lipid index (LI), fibrous cap thickness, and the incidence of thin-cap fibroatheroma (TCFA). Nonculprit plaques in men exhibited greater lipid-core length and LI compared with those of women (9.4 ± 4.5 vs. 7.3 ± 4.3 mm, P = 0.024; 1615.1 ± 893.8 vs. 1237.8 ± 859.8, P = 0.035, respectively). In the univariate linear regression model, sex and current smoker were all associated with a larger LI, whereas only use of statin was independent risk factor for a larger LI in multivariate analysis.

CONCLUSIONS

Coronary nonculprit plaques in male patients with CAD contain larger lipid cores than those of female patients.

Thrombus Formation and Propagation in the Onset of Cardiovascular Events

Ischemic cardiovascular disease is a major cause of morbidity and mortality worldwide and thrombus formation on disrupted atherosclerotic plaques is considered to trigger its onset. Although the activation of platelets and coagulation pathways has been investigated intensively, the mechanisms of thrombus formation on disrupted plaques have not been understood in detail. Platelets are thought to play a central role in the formation of arterial thrombus because of rapid flow conditions; however, thrombus that develops on disrupted plaques consistently includes large amounts of fibrin in addition to aggregated platelets. While, thrombus does not always become large enough to completely occlude the vascular lumen, indicating that the propagation of thrombus is also critical for the onset of cardiovascular events. Various factors, such as vascular wall thrombogenicity, altered blood flow and imbalanced blood hemostasis, modulate thrombus formation and propagation on disrupted plaques. Pathological findings derived from humans and experimental animal models of atherothrombosis have identified important factors that affect thrombus formation and propagation, namely platelets, extrinsic and intrinsic coagulation factors, proinflammatory factors, plaque hypoxia and blood flow alteration. These findings might provide insight into the mechanisms of thrombus formation and propagation on disrupted plaques that lead to the onset of cardiovascular events.

Summation and Cancellation Effects on QRS and ST-Segment Changes Induced by Simultaneous Regional Myocardial Ischemia

Simultaneous ischemia in two myocardial regions is a potentially lethal clinical condition often unrecognized whose corresponding electrocardiographic (ECG) patterns have not yet been characterized. Thus, this study aimed to determine the QRS complex and ST-segment changes induced by concurrent ischemia in different myocardial regions elicited by combined double occlusion of the three main coronary arteries. For this purpose, 12 swine were randomized to combination of 5-min single and double coronary artery occlusion: Group 1: left Circumflex (LCX) and right (RCA) coronary arteries (n = 4); Group 2: left anterior descending artery (LAD) and LCX (n = 4) and; Group 3: LAD and RCA (n = 4). QRS duration and ST-segment displacement were measured in 15-lead ECG. As compared with single occlusion, double LCX+RCA blockade induced significant QRS widening of about 40 ms in nearly all ECG leads and magnification of the ST-segment depression in leads V1-V3 (maximal 228% in lead V3, p < 0.05). In contrast, LAD+LCX or LAD+RCA did not induce significant QRS widening and markedly attenuated the ST-segment elevation in precordial leads (maximal attenuation of 60% in lead V3 in LAD+LCX and 86% in lead V5 in LAD+RCA, p < 0.05). ST-segment elevation in leads V7-V9 was a specific sign of single LCX occlusion. In conclusion, concurrent infero-lateral ischemia was associated with a marked summation effect of the ECG changes previously elicited by each single ischemic region. By contrast, a cancellation effect on ST-segment changes with no QRS widening was observed when the left anterior descending artery was involved.

[Optimal Conditions for 3D Non-contrast T1-weighted Magnetic Resonance Imaging Segmented Turbo Fast Low-angle Shot for Tissue Characterization of Coronary Plaques]

In three-dimensional (3D) T₁-weighted magnetic resonance imaging used for tissue characterization of coronary plaques, the contrast for electrocardiographic synchronization may vary according to the R-R interval (RR). The coronary artery plaque image shows suppression of the fluid compartment signal for the coronary artery luminal blood as well as the fat signal in the region of interest; in addition, it is necessary to ensure that the value of the plaque-to-muscle signal intensity ratio (PMR) does not change according to the difference in RR. In the current study, the phantom review and clinical data suggested that the PMR changes that occur due to the differences in RR can be minimized by adjusting the inversion time (TI) in the range of the required black blood effect. Moreover, the signal-to-noise ratio (SNR), which varies according to the difference between the RR and the TI, was determined to identify the maximum value flip angle (FA) value that would lead to improvement in the SNR. Thus, signal suppression of the PMR, SNR, and the fluid compartment of the coronary artery luminal blood can be controlled using different RRs with the relational expressions for calculating optimal TI and FA.

RNAi targeting multiple cell adhesion molecules reduces immune cell recruitment and vascular inflammation after myocardial infarction

Myocardial infarction (MI) leads to a systemic surge of vascular inflammation in mice and humans, resulting in secondary ischemic complications and high mortality. We show that, in ApoE(-/-) mice with coronary ligation, increased sympathetic tone up-regulates not only hematopoietic leukocyte production but also plaque endothelial expression of adhesion molecules. To counteract the resulting arterial leukocyte recruitment, we developed nanoparticle-based RNA interference (RNAi) that effectively silences five key adhesion molecules. Simultaneously encapsulating small interfering RNA (siRNA)-targeting intercellular cell adhesion molecules 1 and 2 (Icam1 and Icam2), vascular cell adhesion molecule 1 (Vcam1), and E- and P-selectins (Sele and Selp) into polymeric endothelial-avid nanoparticles reduced post-MI neutrophil and monocyte recruitment into atherosclerotic lesions and decreased matrix-degrading plaque protease activity. Five-gene combination RNAi also curtailed leukocyte recruitment to ischemic myocardium. Therefore, targeted multigene silencing may prevent complications after acute MI.

Coronary Plaque Characteristics Associated With Reduced TIMI (Thrombolysis in Myocardial Infarction) Flow Grade in Patients With ST-Segment-Elevation Myocardial Infarction: A Combined Optical Coherence Tomography and Intravascular Ultrasound Study

BACKGROUND

Previous studies reported that reduced TIMI (Thrombolysis in Myocardial Infarction) flow grade before procedure was associated with worse clinical outcomes in patients with ST-segment-elevation myocardial infarction undergoing primary percutaneous coronary intervention. The aim of this study was to identify specific morphological characteristics of the culprit plaque associated with poor TIMI flow grade at baseline in patients with ST-segment-elevation myocardial infarction using both optical coherence tomography and intravascular ultrasound.

METHODS AND RESULTS

A total of 111 ST-segment-elevation myocardial infarction patients who underwent percutaneous coronary intervention within 24 hours of symptom onset were included. Both optical coherence tomography and intravascular ultrasound were performed after thrombectomy. Patients were divided into 2 groups according to preprocedural TIMI flow grade (TIMI 0-1 [n=82] and TIMI 2-3 [n=29]). Patients with preprocedural TIMI 0 to 1 had a greater lipid arc (P=0.037), a longer lipid length (P=0.021), and a greater lipid index (P=0.007) determined by optical coherence tomography and a larger external elastic membrane cross-sectional area (P=0.030) and plaque plus media cross-sectional area (P=0.030) determined by intravascular ultrasound, compared with patients with preprocedural TIMI 2 to 3.

CONCLUSIONS

ST-segment-elevation myocardial infarction patients with reduced TIMI flow grade at baseline have greater lipid burden, larger vessel sizes, and larger plaque areas.

Tissue characterization of non-culprit intermediate coronary lesions in non ST elevation acute coronary syndromes

Background

Disruption of vulnerable plaques is the most common cause of acute coronary syndromes. Intravascular ultrasound facilitates cross-sectional imaging of coronary arteries. We aimed at using IVUS to investigate the morphology and tissue characteristics of atherosclerotic plaques of non-culprit intermediate coronary lesions in non-ST elevation ACS setting.

Methods

IVUS assessment of sixty-one intermediate coronary lesions in twenty-eight patients with the diagnosis of Non ST elevation acute coronary syndromes. Ultrasound signals were obtained by an IVUS system using a 40-MHz catheter.

Results

Mean age was 53.2 ± 9.1 years. Males = 20 (71.4%). Smoking in 17 (60.7%), hypertension in 16 (57.1%), Dyslipidemia in 12 (42.9%) and DM in 8 (28.6%). Culprit vessels represent 42% of affected vessels. Sixty-one intermediate lesions were detected. Twenty-nine lesions in culprit vessels and thirty-two lesions in non-culprit vessels with higher lipidic content in lesions of culprit vessels (P < 0.001) while a higher calcific content in lesions of non-culprit vessels (P < 0.001). Higher calcific content of proximal more than distal lesions (P = 0.048). Negative remodeling in 55.7% of lesions.

Conclusions

A higher lipidic content in lesions of culprit vessels, while the lesions of non-culprit vessels were more calcific. Higher calcific content of proximal more than distal lesions was defined as well.

[Clinical outcomes of intravascular ultrasound in guiding the treatment of non-left main intermediate coronary lesions for patients with acute coronary syndrome]

OBJECTIVE

To evaluate the long-term clinical outcomes of intravascular ultrasound(IVUS) in guiding the treatment of non-left main intermediate coronary lesions for patients of acute coronary syndrome (ACS).

METHODS

A total of 25 patients with intermediate coronary lesions(stenosis of 40%-70%) confirmed by coronary angiography were performed with IVUS. When MLA≥4 mm², we deferred the PCI treatment and performed optimal medical treatment (OMT). The patient were followed up for 12 month. The primary outcome was target vessel revascularization (TVR) and secondary outcome was major adverse cardiac events (MACEs).

RESULTS

A total of 25 lesions of 25 patients were examined by IVUS. 19(76%) lesions were attenuated plaque, 4(16%)were echo-lucent plaque, 2(8%) were calcified plaque. Most of the plaque (18/25, 72%) were eccentric. Positive remodeling was found in 20(80%) lesions and negative remodeling in 5(20%) lesions with meanremodeling index of 1.17=0.15. Thrombus was found in 1 case, accounting for 4%. The diameter stenosis, area stenosis, minimal lumen area and the reference diameter mea-sured by IVUS were larger than those measured by quantitative coronary angiography (all P<0.05). One patient with non-ST segment elevated myocardiac infarction was performed revascularization because MI attacked again, and 2 patients with Unstable angina were treated with OMT but they were still rehospitalization because of angina occurred repeatedly. The incidence of TVR was 4.00%, so as 16.00% of MACE.

CONCLUSION

IVUS can be used to guide the treatment of non-left main intermediate coronary lesions for patients of acute coronary syndrome.

Systemic Versus Coronary Levels of Inflammation in Acute Coronary Syndromes

To address a possible link between systemic and coronary inflammation in the setting of acute coronary syndromes, the authors examined both levels of 3 inflammatory mediators such as high sensitive C-reactive protein (hs-CRP), interleukin (IL)-6, and matrix metalloproteinase (MMP)-9 in patients with the early phase of acute myocardial infarction (AMI). In total, 20 patients with AMI showing minimal elevation of cardiac enzymes were studied. Before angioplasty, peripheral blood and culprit coronary thrombus were sampled to compare systemic and coronary levels of hs-CRP, IL-6, and MMP-9. Relation of systemic levels of hs-CRP and IL-6 to culprit coronary morphology was also evaluated by the use of intravascular ultrasound. Systemic and coronary levels of hs-CRP were nearly equivalent (4.3 ±5.0 vs 4.7 ±5.4 mg/L, p=0.279), whereas IL-6 and MMP-9 showed higher in coronary levels than in systemic levels (169 ±154 vs 93 ±107 pg/mL, p=0.002 and 164 ±116 vs 103 ±94 ng/mL, p=0.018, respectively). Systemic levels of hs-CRP were correlated with coronary levels of IL-6 (r =0.566, p=0.009). Culprit coronary plaque area demonstrated a positive relation with systemic levels of hs-CRP (r =0.466, p=0.038) and also IL-6 (r =0.707, p<0.001). The present study may provide an important insight into the link between systemic and coronary levels of inflammation, which is also associated with vulnerable coronary morphology in the setting of acute coronary syndromes.

High-grade culprit lesions are a common cause of ST-segment elevation myocardial infarction

INTRODUCTION

Conventional knowledge holds that the majority of ruptured atherosclerotic plaques causing ST-segment elevation myocardial infarction (STEMI) are found in moderate stenoses that produce < 50% loss of arterial diameter. This study aimed to analyse the culprit lesions in patients who presented with STEMI and underwent primary percutaneous coronary intervention (PPCI) at our institution.

METHODS

Patients who underwent PPCI between June 2008 and August 2010 at our institution were included in the analysis. Quantitative coronary angiography was performed for the culprit lesions immediately after antegrade flow was restored by thrombectomy, low-profile balloon predilatation or guidewire crossing.

RESULTS

A total of 1,021 patients were included in the study. The mean age was 57 ± 12 years and 85.2% were male. Lesion measurement was done after coronary flow was restored by thrombectomy (73.1%), balloon dilatation (24.1%) and following guidewire passage across the lesion (2.8%). Mean minimal luminal diameter was 1.1 ± 0.5 mm, mean reference vessel diameter was 2.8 ± 0.6 mm, mean diameter stenosis was 61 ± 16% and mean lesion length was 16 ± 6 mm. Most (80.2%) of the culprit lesions had diameter stenoses > 50% (p < 0.01). Although balloon angioplasty was performed in 24.1% of the patients, the majority (64.2%) still had diameter stenoses > 50%. High-grade stenoses (> 50%) were more frequently observed in male patients (p = 0.04).

CONCLUSION

Contrary to the existing paradigm, we found that most of the patients with STEMI in our institution had culprit lesions with diameter stenosis > 50%.

Comparison of plaque characteristics in narrowings with ST-elevation myocardial infarction (STEMI), non-STEMI/unstable angina pectoris and stable coronary artery disease (from the ADAPT-DES IVUS Substudy)

Assessment of Dual Antiplatelet Therapy With Drug-Eluting Stents (ADAPT-DES) was a prospective, multicenter registry of 8,582 consecutive stable and unstable patients who underwent percutaneous coronary intervention using a drug-eluting stent. We sought to identify key morphologic features leading to ST-segment elevation myocardial infarction (STEMI) versus non-STEMI (NSTEMI) or unstable angina pectoris (UA) versus stable coronary artery disease (CAD) presentation. In the prespecified grayscale and virtual histology (VH) substudy of ADAPT-DES, preintervention imaging identified 676 patients with a single culprit lesion. The relation between lesion morphology and clinical presentation was compared among patients with (1) STEMI, (2) NSTEMI or UA, and (3) stable CAD. Intravascular ultrasound identified more plaque rupture and VH thin-cap fibroatheroma (TCFA) in STEMI lesions compared with NSTEMI/UA or stable CAD lesions; conversely, fibroatheromas appeared more often calcified with a thick fibrous cap in stable CAD. Minimum lumen cross-sectional area (MLA) was smaller with larger plaque burden and positive remodeling in STEMI lesions. Lesions with plaque rupture versus those without plaque rupture showed higher prevalence of VH-TCFA and larger plaque burden with positive remodeling, especially in patients with STEMI. Multivariate analysis showed that in the lesions with plaque rupture, plaque burden at the MLA site was the only independent predictor for STEMI (cutoff of plaque burden = 85%) and in lesions without plaque rupture, MLA was the only independent predictor for STEMI (cutoff of MLA = 2.3 mm(2)). In conclusion, culprit lesions causing STEMI have smaller lumen areas, greater plaque burden, and more plaque rupture or VH-TCFA compared with NSTEMI/UA or stable CAD; in lesions with plaque rupture, only plaque burden predicted STEMI, and in lesions without plaque rupture, only MLA area predicted STEMI.

Differences in intravascular ultrasound and histological findings in culprit coronary plaques between ST-segment elevation myocardial infarction and stable angina

A comprehensive evaluation of culprit coronary lesions may help to understand vulnerable plaques responsible for ST-segment elevation myocardial infarction (STEMI). We compared intravascular ultrasound (IVUS) and histological findings in culprit coronary plaques from 94 patients with STEMI (n = 54) or stable angina (n = 40). Tissue specimens were obtained by directional coronary atherectomy and IVUS was performed before percutaneous coronary intervention. IVUS and histological data were analyzed. Clinical characteristics were largely similar between the two groups. Plaque rupture and thrombi were more frequently found in the STEMI group than in the stable angina group. There were no significant differences between plaque types or proximal and distal reference measurements in the two groups. However, the site of minimal lumen area had a greater vessel area, remodeling index, and plaque burden with lesser lumen area in the STEMI group than in the stable angina group. Plaque areas immunopositive for CD68 and CD31 were significantly larger in the STEMI group, while the area immunopositive for α-smooth muscle actin was larger in the stable angina group. In conclusion, culprit lesions in STEMI patients showed a greater plaque burden, remodeling index, and more frequent thrombi with increased inflammation and neovascularization compared to the stable angina group, supporting the current concept of vulnerable plaques being responsible for STEMI.

The myth of the "vulnerable plaque": transitioning from a focus on individual lesions to atherosclerotic disease burden for coronary artery disease risk assessment

The cardiovascular science community has pursued the quest to identify vulnerable atherosclerotic plaque in patients for decades, hoping to prevent acute coronary events. However, despite major advancements in imaging technology that allow visualization of rupture-prone plaques, clinical studies have not demonstrated improved risk prediction compared with traditional approaches. Considering the complex relationship between plaque rupture and acute coronary event risk suggested by pathology studies and confirmed by clinical investigations, these results are not surprising. This review summarizes the evidence supporting a multifaceted hypothesis of the natural history of atherosclerotic plaque rupture. Managing patients at risk of acute coronary events mandates a greater focus on the atherosclerotic disease burden rather than on features of individual plaques.

Imaging plaques to predict and better manage patients with acute coronary events

Culprit lesions of patients, who have had an acute coronary syndrome commonly, are ruptured coronary plaques with superimposed thrombus. The precursor of such lesions is an inflamed thin-capped fibroatheroma. These plaques can be imaged by means of invasive techniques, such as intravascular ultrasound (and derived techniques), optical coherence tomography, and near-infrared spectroscopy. Often these patients exhibit similar (multiple) plaques beyond the culprit lesion. These remote plaques can be assessed noninvasively by computed tomographic angiography and MRI and also using invasive imaging. The detection of these remote plaques is not only feasible but also in natural history studies have been associated with clinical coronary events. Different systemic pharmacological treatments have been studied (mostly statins) with modest success and, therefore, newer approaches are being tested. Local treatment for such lesions is in its infancy and larger, prospective, and randomized trials are needed. This review will describe the pathological and imaging findings in culprit lesions of patients with acute coronary syndrome and the assessment of remote plaques. In addition, the pharmacological and local treatment options will be reviewed.

Advances in mechanisms, imaging and management of the unstable plaque

Post-mortem observations demonstrated that plaque fissure was the final event leading to coronary thrombosis and occlusion in about two-thirds of cases of sudden coronary death. Plaques prone to fissure have, therefore, been defined "vulnerable plaques" and are identified by specific anatomic features including thin inflamed fibrous cap, large lipidic core and positive remodeling. Accordingly, elegant imaging modalities have been developed in order to identify this "holy grail". However, the results of prognostic studies based on the identification of vulnerable plaques have not been encouraging because of the low positive predictive value for major cardiovascular events. This observation is not surprising as the pathogenesis of acute coronary syndromes is complex and multifactorial. In this review we propose a pathogenetic classification of acute coronary syndromes in the attempt to identify homogeneous groups of patients with a common mechanism of coronary instability which can be identified by using specific biomarkers and imaging techniques, and become a specific therapeutic target.

Detection by near-infrared spectroscopy of large lipid core plaques at culprit sites in patients with acute ST-segment elevation myocardial infarction

OBJECTIVES

This study sought to describe near-infrared spectroscopy (NIRS) findings of culprit lesions in ST-segment elevation myocardial infarction (STEMI).

BACKGROUND

Although autopsy studies demonstrate that most STEMI are caused by rupture of pre-existing lipid core plaque (LCP), it has not been possible to identify LCP in vivo. A novel intracoronary NIRS catheter has made it possible to detect LCP in patients.

METHODS

We performed NIRS within the culprit vessels of 20 patients with acute STEMI and compared the STEMI culprit findings to findings in nonculprit segments of the artery and to findings in autopsy control segments. Culprit and control segments were analyzed for the maximum lipid core burden index in a 4-mm length of artery (maxLCBI(4mm)).

RESULTS

MaxLCBI(4mm) was 5.8-fold higher in STEMI culprit segments than in 87 nonculprit segments of the STEMI culprit vessel (median [interquartile range (IQR)]: 523 [445 to 821] vs. 90 [6 to 265]; p < 0.001) and 87-fold higher than in 279 coronary autopsy segments free of large LCP by histology (median [IQR]: 523 [445 to 821] vs. 6 [0 to 88]; p < 0.001).Within the STEMI culprit artery, NIRS accurately distinguished culprit from nonculprit segments (receiver-operating characteristic analysis area under the curve = 0.90). A threshold of maxLCBI(4mm) >400 distinguished STEMI culprit segments from specimens free of large LCP by histology (sensitivity: 85%, specificity: 98%).

CONCLUSIONS

The present study has demonstrated in vivo that a maxLCBI(4mm) >400, as detected by NIRS, is a signature of plaques causing STEMI.