The Relationship Between Attenuated Plaque Identified by Intravascular Ultrasound and No-Reflow After Stenting in Acute Myocardial Infarction

Suppression of Bim by microRNA-19a may protect cardiomyocytes against hypoxia-induced cell death via autophagy activation

Microvascular obstruction (MO), one of unfavorable complications of percutaneous coronary intervention (PCI), is responsible for the lost benefit of reperfusion therapy. Determination of microRNA-19a, a member of the miR-17-92 cluster, using quantitative real-time polymerase chain reaction (PCR) revealed notably down-regulated microRNA-19a, in myocardium with MO. Nonetheless, the role of miR-19a in MO and the underlying mechanism remains to be elucidated. To this end, an in vitro microembolization model in cardiomyocytes was used. Our data revealed that hypoxic exposure prompted cardiomyocyte apoptosis in a time-dependent manner accompanied by reduced miR-19a. miR-19a overexpression clearly ameliorated hypoxia-induced cell death (necrosis and apoptosis), at least in part, through switching on autophagy. Further dual-luciferase reporter assay and immunoblotting studies demonstrated that miR-19a-induced cytoprotection might be achieved in part through modulation of the specific target Bcl-2 interacting mediator of cell death, Bim, an apoptotic activator. Bim sufficiently interfered with miR-19a-induced LC3 conversion and increased cardiomyocyte apoptosis under hypoxia. Moreover, cardiomyocytes pretreated with 3-methyladenine conferred resistance to the cytoprotective effect of miR-19a and displayed notably increased TUNEL staining and caspase-3 activity. In conclusion, miR-19a protected cardiomyocytes against hypoxia-induced lethality at least in part via Bim suppression and subsequently autophagy activation.

Impact of attenuated plaques on TIMI grade flow and clinical outcomes of coronary artery disease patients: a systematic review and meta analysis

BACKGROUND

Plaques with a large necrotic core or lipid pool and thin-cap fibroatheroma manifest as attenuated plaques on intravascular ultrasound (IVUS). Their impact on TIMI grade flow and clinical outcomes remains undefined. We performed a systematic review and meta-analysis to summarize the association between attenuated plaque and distal embolization and clinical outcomes of coronary artery disease (CAD) from pooled data of published eligible cohort studies.

METHODS

We searched the literature on TIMI grade flow and clinical outcomes on PubMed, Ovid, EMBASE, the Cochrane Library, CNKI and WanFang databases. Study heterogeneity and publication bias were estimated.

RESULTS

A total of 3,833 patients were enrolled in nine studies. Five studies investigated TIMI grade flow and attenuated plaques. They revealed no difference in TIMI grade flow before percutaneous coronary intervention (PCI) between the attenuated and non-attenuated plaque group (RR =1.25; 95% CI: 0.65 to 2.41; P=0.50). After balloon dilation and stent implantation, the incidence of TIMI 0~2 grade flow in the attenuated plaque group was statistically significant higher than that of the non-attenuated plaque group (RR =4.73; 95% CI: 3.03 to 7.40; P<0.001). Five other studies investigated major cardiovascular events (MACEs) and attenuated plaques and found no difference in MACE rates within three years of follow up.

CONCLUSIONS

Our study presents the evidence that plaque with ultrasound signal attenuation would induce slow/no reflow phenomenon and distal embolization during PCI, but this appearance has no impact on MACE rates within three years.

Usefulness of Intravascular Ultrasound for Predicting Risk of Intraprocedural Stent Thrombosis

Intraprocedural stent thrombosis (IPST) is a rare complication of percutaneous coronary intervention that leads to poor outcomes; however, the factors contributing to IPST remain largely unknown. Accordingly, we used intravascular ultrasound (IVUS) to examine the lesion characteristics in patients with IPST. We retrospectively analyzed 1,504 consecutive stent-implanted lesions in 1,324 patients (326 with ST-segment elevation myocardial infarction [STEMI], 403 patients with non-ST-segment elevation acute coronary syndrome [NSTE-ACS], and 595 patients with stable angina). Of these, IPST occurred in 5 patients during percutaneous coronary intervention (0.4% per patient; 3 with STEMI, 2 with NSTE-ACS). The IVUS characteristics of plaques that developed IPST were compared with those of controls without the evidence of IPST (non-IPST; n = 15) who were matched by age, gender, lesion location, and clinical presentation (STEMI, NSTE-ACS, or stable angina). All 5 lesions that led to IPST had ruptured plaques with positive remodeling and attenuation. Plaque rupture was also observed in 40% of the non-IPST group. Multiple plaque ruptures in the culprit lesion were more common in the IPST group (80% vs 7%; p <0.01). The maximum cavity area was larger in the IPST group than in the non-IPST group having plaque rupture (4.6 mm(2) [interquartile range, 4.3 to 6.5] vs 2.4 mm(2) [1.8 to 2.9]; p <0.01). In conclusion, we found using IVUS that multiple plaque ruptures with larger cavities more often evolved into IPST.

Level of Pregnancy-associated Plasma Protein-A Correlates With Coronary Thin-cap Fibroatheroma Burden in Patients With Coronary Artery Disease: Novel Findings From 3-Vessel Virtual Histology Intravascular Ultrasound Assessment

Pregnancy-associated plasma protein-A (PAPP-A) level is an independent predictor of acute cardiovascular event occurrence. To test the hypothesis that increased PAPP-A levels would be associated with a higher burden of coronary thin-cap fibroatheroma (TCFA) thereby underlying the heightened risk for cardiovascular events in patients with coronary artery disease; 154 patients (462 vessels and 975 plaques) with stable angina or non-ST-segment elevation acute coronary syndrome (NSTE-ACS) referred for percutaneous coronary intervention were assessed using 3-vessel virtual histology (VH)-intravascular ultrasound (IVUS). Thin-cap fibroatheroma virtual histology was defined as focal, necrotic core (NC)-rich (≥10% of cross-sectional area) plaques in contact with the lumen, and plaque burden ≥40%. Pregnancy-associated plasma protein-A levels were determined by sandwich enzyme-linked immunosorbent assay, and patients were divided into 3 groups based on PAPP-A level tertiles. Although the highest PAPP-A level tertile was not associated with 3-vessel plaque number, it was associated with 3-vessel VH-TCFA number and necrotic core volume. Patients with ≥3 VH-TCFAs had a higher PAPP-A level than patients with 1 to 3 VH-TCFAs or without any VH-TCFA (13.3 ± 11.8 versus 7.8 ± 4.7 versus 7.4 ± 4.7 mIU/L, P < 0.001, respectively). Moreover, PAPP-A level was an independent predictor of higher total number of VH-TCFAs (OR 1.18; 95% CI 1.07-1.29, P = 0.001). This VH-IVUS study demonstrated, for the first time to our knowledge, that higher PAPP-A levels are associated with higher 3-vessel TCFA burden in patients with coronary artery disease. Pregnancy-associated plasma protein-A, therefore, might be a useful serum biomarker to predict increased coronary TCFA burden and plaque instability.

Predictors and outcome of no-reflow post primary percutaneous coronary intervention for ST elevation myocardial infarction

Background

No-reflow (TIMI < 3) during primary PCI (PCI) for STEMI occurs in 11–41% of cases, indicates poor myocardial tissue perfusion, and is associated with a poor outcome. We aimed to determine predictors and 12 month outcomes of patients who developed no-reflow.

Methods

We analysed the PCI database of The Canberra Hospital and identified 781 patients who underwent primary PCI during 2008–2012. Follow-up at 12 months was with letter, phone call and review of hospital records.

Results

No-reflow was observed in 189 patients (25%) at the end of the procedure. Patients with no-reflow were older (64 vs. 61 years, p = 0.03). No-reflow patients were more likely to have initial TIMI flow < 3 (89% vs. 79%, p = 0.001), thrombus score ≥ 4 (83% vs. 69%, p = 0.0001), higher use of glycoprotein IIb/IIIa inhibitors (57% vs. 48%, p = 0.03) and longer median symptom to balloon time (223 min vs. 192 min, p = 0.004). No-reflow was an independent predictor of mortality (HR 1.95, CI 1.04-3.59, p = 0.037) during 12 month follow-up. On multivariate analysis, age > 60 years, thrombus score ≥ 4 and symptom to balloon time > 360 min were independent predictors of no-reflow. In 17% of cases of no reflow, it occurred only after stent insertion.

Conclusions

No-reflow occurred in 25% of STEMI patients undergoing primary PCI and was more likely with older age, high thrombus burden and delayed presentation. No-reflow was associated with a higher risk of death at 12 month follow-up.

Role of Intravascular Ultrasound in Patients with Acute Myocardial Infarction

Rupture of a vulnerable plaque and subsequent thrombus formation are important mechanisms leading to the development of an acute myocardial infarction (AMI). Typical intravascular ultrasound (IVUS) features of AMI include plaque rupture, thrombus, positive remodeling, attenuated plaque, spotty calcification, and thin-cap fibroatheroma. No-reflow phenomenon was attributable to the embolization of thrombus and plaque debris that results from mechanical fragmentation of the vulnerable plaque by percutaneous coronary intervention (PCI). Several grayscale IVUS features including plaque rupture, thrombus, positive remodeling, greater plaque burden, decreased post-PCI plaque volume, and tissue prolapse, and virtual histology-IVUS features such as large necrotic corecontaining lesion and thin-cap fibroatheroma were the independent predictors of no-reflow phenomenon in AMI patients. Non-culprit lesions associated with recurrent events were more likely than those not associated with recurrent events to be characterized by a plaque burden of ≥70%, a minimal luminal area of ≤4.0 mm(2), or to be classified as thin-cap fibroatheromas.

Myocardial Injury after Percutaneous Coronary Intervention for In-Stent Restenosis Versus de novo Stenosis

OBJECTIVE

Periprocedural myocardial injury (PMI) remains a relatively common complication even after successful procedures. In-stent restenosis (ISR) may be involved in lesion-related factors for PMI. We compared the incidence of PMI between patients with ISR and those with de novo stenosis.

METHODS

The study population consisted of 121 patients with coronary artery disease who had been treated with statins and subsequently underwent angiographically successful percutaneous coronary intervention (PCI). Blood samples for troponin I were collected 18 to 24 hours after PCI. PMI was defined as an increase in the troponin I levels greater than 0.15 ng/mL. Major PMI was defined as an increase in the troponin I levels greater than 0.75 ng/mL.

RESULTS

There were 34 patients with ISR and 87 patients with de novo stenosis. The incidence of PMI was similar between the two groups (47.1 % vs. 55.2 %, p=0.42). Among the patients with ISR, the incidences of PMI were 33.3 %, 60.0 % and 66.7 % in patients with focal ISR, diffuse ISR and diffuse proliferative ISR, respectively, although these differences were not statistically significant. The incidence of major PMI was significantly less frequent in patients with ISR than those with de novo stenosis (5.9 % vs. 25.3 %, p=0.03). A multivariate logistic regression analysis showed that ISR [odds ratio (OR) 0.22, 95% confidence interval (CI) 0.03-0.90; p=0.03] and the maximum inflation pressure (OR 1.15, 95% CI 1.04-1.30; p=0.009) were independent predictors of major PMI.

CONCLUSION

Our results suggest that while PMI occurs in patients with ISR as commonly as those with de novo stenosis, major PMI occurs less frequently in patients with ISR.

Long-term prognostic impact of the attenuated plaque in patients with acute coronary syndrome

Several intravascular ultrasound studies have reported that culprit lesion-attenuated plaque (AP) is related to slow flow/no reflow after percutaneous coronary intervention (PCI). Long-term prognostic impact of the AP is unknown. The aim of this study was to investigate acute and long-term clinical impact of the AP in patients with acute coronary syndrome (ACS). A total of 110 ACS patients who underwent successful PCI were enrolled. Acute and long-term clinical outcomes were compared between patients with AP (AP group: n = 73) and those without AP (non-AP group: n = 37). Long-term cardiac event was defined as a composite of death and ACS. Baseline characteristics in 2 groups were similar. AP was associated with higher TIMI frame count immediately after the first balloon inflation. After thrombectomy and intracoronary drug administration, final TIMI frame count became similar between AP and non-AP group. Although AP was associated with higher incidence of fatal arrhythmia during hospitalization, in-hospital mortality did not differ between the 2 groups. During follow-up (median 6.2 years), cardiac event-free survival did not differ between the 2 groups. Despite the initial unfavorable effect on coronary reflow, presence of AP did not affect acute as well as long-term clinical outcome in patients with ACS.

Expectations and limitations of contemporary intravascular imaging: lessons learned from pathology

Acute coronary syndrome is the leading cause of death worldwide and plaque rupture is the most common underlying mechanism of coronary thrombosis. During the last 2 decades the understanding of atherosclerotic plaque progression advanced dramatically and pathology studies provided fundamental insights of underlying plaque morphology, which paved the way for invasive imaging modalities, which bring a new area of atherosclerotic plaque characterization in vivo. The development of intravascular ultrasound (IVUS) allowed the field to evaluate the principles of vascular anatomy, which is often underestimated by coronary angiography. Furthermore, IVUS image technologies were developed to obtain improved characterization of plaque composition. However, since spatial resolution of IVUS is insufficient to distinguish details of plaque morphology, a broad adoption of this technology in clinical practice was missing. Optical coherence tomography is a light-based imaging modality with higher spatial resolution compared to IVUS, which enables the assessment of vascular anatomy with great detail.

Intravascular ultrasound analysis to determine the relationship between high-density lipoprotein cholesterol and lesion characteristics in patients with coronary artery disease

OBJECTIVES

This study utilized grayscale intravascular ultrasound (IVUS) to explore the relationship between high-density lipoprotein cholesterol (HDL-C) levels and culprit lesion characteristics in patients with coronary artery disease.

BACKGROUND

Low HDL-C is associated with an increased risk of cardiovascular events. Previous IVUS studies have suggested a significant association between lesion characteristics and cardiovascular events.

METHODS

According to HDL-C levels, 120 patients who underwent IVUS for native, de novo coronary lesions before any intervention were divided into a low HDL-C group (<40 mg/dL, n = 60) and a high HDL-C group (≥40 mg/dL, n = 60). Quantitative and qualitative IVUS analyses were performed to compare lesion characteristics.

RESULTS

Quantitative IVUS measurements showed no significant differences between the 2 groups. HDL-C level was not significantly correlated with remodeling index (r = 0.03, P = 0.78). However, attenuated plaque was more frequent in the low HDL-C group (48.3% vs. 28.3%, P = 0.02) and a greater percentage of attenuated plaque was found in this group (32.5 ± 21.3% vs. 21.0 ± 11.0%, P = 0.02). Moreover, when categorized into 4 groups according to HDL-C levels, the proportion of attenuated plaque (64.7% in group with <30 mg/dL, 41.9% in group with 30-39 mg/dL, 36.4% in group with 40-59 mg/dL, and 6.3% in group with ≥60 mg/dL; P = 0.001 for trend) was significantly different among groups. On multivariate analysis, only HDL-C and male gender were independently associated with the presence of attenuated plaque at the culprit lesions.

CONCLUSIONS

Patients with low levels of HDL-C may be at increased risk of having a higher incidence of attenuated plaques.

Clinical utility of intravascular imaging and physiology in coronary artery disease

Intravascular imaging and physiology techniques and technologies are moving beyond the framework of research to inform clinical decision making. Currently available technologies and techniques include fractional flow reserve; grayscale intravascular ultrasound (IVUS); IVUS radiofrequency tissue characterization; optical coherence tomography, the light analogue of IVUS; and near-infrared spectroscopy that detects lipid within the vessel wall and that has recently been combined with grayscale IVUS in a single catheter as the first combined imaging device. These tools can be used to answer questions that occur during daily practice, including: Is this stenosis significant? Where is the culprit lesion? Is this a vulnerable plaque? What is the likelihood of distal embolization or periprocedural myocardial infarction during stent implantation? How do I optimize acute stent results? Why did thrombosis or restenosis occur in this stent? One of the legacies of coronary angiography is to presume that one technique will answer all of these questions; however, that often has been proved inaccurate in contemporary practice.

The vulnerable plaque: current concepts and future perspectives on coronary morphology, composition and wall stress imaging

Cardiovascular imaging plays an important role in the identification and characterization of the vulnerable plaque. A major goal is the ability to identify individuals at risk of plaque rupture and developing an acute coronary syndrome. Early recognition of rupture-prone atherosclerotic plaques may lead to the development of pharmacologic and interventional strategies to reduce acute coronary events. We review state-of-the-art cardiovascular imaging for identification of the vulnerable plaque. There is ample evidence of a close relationship between plaque morphology and patient outcome, but molecular imaging can add significant information on tissue characterization, inflammation and subclinical thrombosis. Additionally, identifying arterial wall exposed to high shear stress may further identify rupture-prone arterial segments. These new modalities may help reduce the individual, social and economic burden of cardiovascular disease.

Plaque characteristics and serum pregnancy-associated plasma protein A levels predict the no-reflow phenomenon after percutaneous coronary intervention

OBJECTIVES

To investigate the relationship between serum plasma pregnancy-associated plasma protein A (PAPP-A) and coronary plaque characteristics, and their prognostic value for coronary no-reflow after percutaneous coronary intervention (PCI).

METHODS

Patients with unstable angina undergoing PCI were divided into a normal reflow group and a no-reflow group after stent deployment. Coronary blood flow was measured angiographically; plaque components were detected by virtual histology intravascular ultrasound. Serum PAPP-A and high-sensitivity C-reactive protein (hsCRP) were measured before PCI. Cardiac troponin T (cTnT) was measured before and 24 h after PCI.

RESULTS

A total of 166 patients with unstable angina undergoing PCI were included: normal reflow group (n = 145) and no-reflow group (n = 21), after stent deployment. Baseline coronary blood flow was similar in the two groups. The no-reflow group had plaques with less-fibrotic tissue and a larger necrotic core, more thin-cap fibroatheromas and plaque ruptures, and higher serum PAPP-A, hsCRP and post-PCI cTnT levels than the normal reflow group. Serum PAPP-A was correlated negatively with plaque fibrotic area and positively with necrotic core area.

CONCLUSION

High serum PAPP-A and plaque lesions with a large necrotic core are associated with the no-reflow phenomenon after PCI, in patients with unstable angina.