Acute coronary syndrome: insight from angioscopy

Hepatic steatosis evidenced by computed tomography in patients undergoing primary percutaneous coronary intervention for acute myocardial infarction

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) and acute myocardial infarction (AMI) have common pathological links. This study investigates the prognostic impact of NAFLD assessed as hepatic steatosis (HS) by computed tomography (CT) in AMI patients and explores the mechanistic role of NAFLD in cardiovascular (CV) events using coronary angioscopy (CAS).

METHODS

We retrospectively examined 342 AMI patients who underwent CT followed by primary percutaneous coronary intervention (PCI) between January 2014 and December 2019. HS was defined as a hepatic to spleen attenuation ratio of <1.0 on CT scans. Major cardiac events (MCE) included cardiac death, non-fatal myocardial infarction, target-vessel revascularization, and target-lesion revascularization.

RESULTS

HS was identified in 88 patients (26 %). Patients with HS were significantly younger, had a higher body mass index, and higher hemoglobin A1c, triglyceride, and malondialdehyde low-density lipoprotein levels (all p < 0.05). MCE occurred more frequently [27 (30.7 %) vs. 39 (15.4 %), p = 0.001] in the HS group than in the non-HS group. In the multivariate analysis, the presence of HS was an independent predictor of MCE after adjusting for metabolic risk factor and liver function markers. Among the 74 patients who underwent CAS for a median of 15 days after primary PCI, 51 (69 %) had intrastent thrombus, which was strongly associated with the presence of HS [18 (35 %) vs. 1 (4 %), p = 0.005].

CONCLUSIONS

AMI patients with NAFLD detected by CT often had CAS-derived intrastent thrombi and were at a high risk for CV events. Therefore, these patients should be carefully monitored.

Efficacy and safety of low dose rivaroxaban in patients with coronary heart disease: a systematic review and meta-analysis

The mortality effects and risk-benefit profile of low dose rivaroxaban (2.5 mg twice daily) in patients with coronary heart disease are not completely understood. Five randomized controlled trials (26,110 patients) were selected using PubMed and Cochrane library till April 2019. The background antiplatelet therapy was aspirin in 3 trials, P2Y12 inhibitor in 1 trial, and in 1 trial 65% patients received aspirin and 35% were on dual antiplatelet therapy (DAPT). The outcomes of interest were cardiovascular mortality, all-cause mortality, myocardial infarction (MI), stroke and major bleeding events. Random effects hazard ratios (HR) with 95% confidence intervals (CI) were calculated. Low dose rivaroxaban did not reduce the risk of cardiovascular mortality (HR 0.90, 95% CI 0.73-1.11, P = 0.34) or all-cause mortality (HR 0.91, 95% CI 0.74-1.12, P = 0.38) compared with control. However, low dose rivaroxaban was associated with reduction in MI (HR 0.85, 95% CI 0.73-0.99, P = 0.04), and stroke (HR 0.59, 95%CI 0.48-0.73, P < 0.001) at the expense of major bleeding (HR 1.64, 95% CI 1.39-1.94, P < 0.001) compared with control. These effects did not vary according to acute coronary syndrome or stable coronary heart disease (P-interaction > 0.05). The use of low dose rivaroxaban in patients with coronary heart disease predominantly receiving antiplatelet monotherapy did not reduce cardiovascular or all-cause mortality. The benefits of preventing MI and stroke were balanced by increased risk of major bleeding.

Correlation between small and dense low-density lipoprotein cholesterol and cardiovascular events in Beijing community population

The relationship between small dense low‐density lipoprotein cholesterol (sdLDL‐C) and different cardiovascular events has been observed in several large community studies, and the results have been controversial. However, there is currently no cross‐sectional or longitudinal follow‐up study on sdLDL‐C in the Chinese hypertension population. We analyzed the association of plasma sdLDL‐C levels with major adverse cardiovascular events in 1325 subjects from a longitudinal follow‐up community‐based population in Beijing, China. During the follow‐up period, a total of 191 subjects had MACEs. Cox regression analysis showed that sdLDL‐C is a major risk factor for MACEs independent of sex, age, BMI, hypertension, diabetes, smoking, SBP, DBP, FBG, eGFR in the general community population (1.013 (1.001 −1.025, P < .05)), but the correlation disappeared after adjusting for TC and HDL‐C in Model 3. Cox analysis showed that hypertension combined with high level of sdLDL‐C was still the risk factor for MACEs ((2.079 (1.039‐4.148)). Our findings in the Chinese cohort support that sdLDL‐C is a risk factor for major adverse cardiovascular events in hypertension subjects.

Gender based differences in clinical and Angiographic characteristics and outcomes of Acute Coronary Syndrome (ACS) in Asian population

Objective:

There is very limited data about gender based differences in Acute Coronary Syndrome (ACS) in Asian population. This study was therefore aimed to ascertain gender based differences in clinical and angiographic characteristics and clinical outcomes in patient admitted with ACS.

Methods:

This was a cross sectional, observational study including patients admitted with diagnosis of ACS. Patients were divided into two groups (Males and Females) and their clinical characteristics were noted. Gender based assessment was done following coronary angiography.

Results:

A total of 386 patients were included, with 210 males and 176 females. Anterior wall myocardial infarction (AWMI) was present in 177(45.86%) patients. Mean age was 72.8±12.9 years in females and 66.8±11.2 years in males. Diabetes was present in 38.1% females and 31% males. Patients from rural population were 225(58.3%), while from urban 161(41.7%). Mean ejection fraction was 43.9±7.9% in women and 38.2±8.68% in males.

Conclusion:

ACS was more common in males, rural population and AWMI was most common cause. Women were more elderly and had more adverse events as compared to males. Impaired renal dynamics were more commonly observed in males. Women were less aggressively treated with coronary interventions and radial approach was better tolerated regardless of gender.

The role of sphingosine 1 phosphate in coronary artery disease and ischemia reperfusion injury

Coronary artery disease (CAD) is a common cause of morbidity and mortality worldwide. Atherosclerotic plaques, as a hallmark of CAD, cause chronic narrowing of coronary arteries over time and could also result in acute myocardial infarction (AMI). The standard treatments for ameliorating AMI are reperfusion strategies, which paradoxically result in ischemic reperfusion (I/R) injury. Sphingosine 1 phosphate (S1P), as a potent lysophospholipid, plays an important role in various organs, including immune and cardiovascular systems. In addition, high-density lipoprotein, as a negative predictor of atherosclerosis and CAD, is a major carrier of S1P in blood circulation. S1P mediates its effects through binding to specific G protein-coupled receptors, and its signaling contributes to a variety of responses, including cardiac inflammation, dysfunction, and I/R injury protection. In this review, we will focus on the role of S1P in CAD and I/R injury as a potential therapeutic target.

Endogenous Interleukin-1β Is Implicated in Intraplaque Hemorrhage in Apolipoprotein E Gene Null Mice

BACKGROUND

Intraplaque hemorrhage (IPH) has been implicated in plaque instability and rupture in atherosclerotic lesions, although the mechanisms by which IPH progresses remain largely unknown. In this study, apolipoprotein E-deficient mice with carotid artery ligation and cuff placement around the artery were used, and pro-inflammatory cytokines that are implicated in IPH were analyzed.Methods and Results:The expression of interleukin-1β (IL-1β) increased significantly following cuff placement compared with mice with carotid artery ligation alone. IPH occurred in the cuff-placed carotid artery following treatment with the negative control (NC) small interfering RNA (siRNA). However, the occurrence was significantly reduced in the cuff-placed carotid artery following treatment with an IL-1β siRNA. Neovessel formation was significantly reduced in the carotid artery treated with the NC siRNA compared with that treated with IL-1β siRNA. IL-1β significantly inhibited the tube formation and wound healing capacities of vascular endothelial cells in vitro. Furthermore, immunostaining of matrix metalloproteinase-9 (MMP-9) significantly increased in the carotid artery treated with the NC siRNA compared with that treated with IL-1β siRNA.

CONCLUSIONS

These results suggest that endogenous IL-1β is implicated in the progression of IPH via the inhibition of physiological angiogenesis in the atherosclerotic plaque, leading to the formation of leaky neovessels. Furthermore, the stimulation of MMP-9 expression may also contribute to the formation of leaky neovessels.

Targeting blood thrombogenicity precipitates atherothrombotic events in a mouse model of plaque destabilization

Although some features of plaque instability can be observed in genetically modified mouse models, atherothrombosis induction in mice has been attested to be difficult. We sought to test the hypothesis that alterations in blood thrombogenicity might have an essential role in the development of atherothrombosis in ApoE-/- mice. In a mouse model of plaque destabilization established in our laboratory, we targeted blood thrombogenicity by systemically overexpressing murine prothrombin via adenovirus-mediated gene transfer. Systemic overexpression of prothrombin increased blood thrombogenicity, and remarkably, precipitated atherothrombotic events in 70% of the animals. The affected plaques displayed features of culprit lesions as seen in human coronary arteries, including fibrous cap disruption, luminal thrombosis, and plaque hemorrhage. Treatment with aspirin and clopidogrel substantially reduced the incidence of atherothrombosis in this model. Mechanistically, increased inflammation, apoptosis and upregulation of metalloproteinases contributed to the development of plaque destabilization and atherothrombosis. As conclusions, targeting blood thrombogenicity in mice can faithfully reproduce the process of atherothrombosis as occurring in human coronary vessels. Our results suggest that blood-plaque interactions are critical in the development of atherothrombosis in mice, substantiating the argument that changes in blood coagulation status may have a determinant role in the onset of acute coronary syndrome.

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.

Progression of coronary atherosclerosis in stable patients with ultrasonic features of high-risk plaques

AIM

Large plaque burden, expansive vascular remodelling, and spotty calcification have been considered as important morphologies of high-risk plaques causing acute coronary events. Although non-occlusive rupture of high-risk plaques has been proposed as a mechanism for disease progression in post-mortem studies, the natural history of coronary atherosclerosis in stable patients with high-risk plaques has not been fully elucidated. We sought to evaluate coronary atheroma progression in stable patients with greyscale intravascular ultrasound (IVUS)-derived high-risk plaques.

METHODS AND RESULTS

We analysed 4477 patients with stable coronary artery disease underwent serial greyscale IVUS imaging in eight clinical trials. We compared volumetric intravascular ultrasound (IVUS) data in the non-culprit segments between patients with and without high-risk plaques, defined as the combination of per cent atheroma volume (PAV) >63%, positive remodelling and spotty calcification. High-risk plaques were observed in 201 (4.5%) of patients. Patients with high-risk plaques exhibited a greater PAV (47.1 ± 8.4 vs. 37.7 ± 8.7%, P < 0.001) at baseline. On serial evaluation, however, regression of PAV (-0.26 ± 0.39 vs. 0.24 ± 0.32%, P = 0.03) was observed. In patients with high-risk plaques, the non-statin use was associated with the accelerated atheroma progression, whereas atheroma regression was observed under statin therapy (change in PAV: 1.87 ± 0.68% vs. -0.83 ± 0.53%, P = 0.01).

CONCLUSIONS

Patients with high-risk plaques exhibit extensive atheroma burden, which is modifiable with anti-atherosclerotic therapies. These findings underscore risk modification using a statin in patients with high-risk plaques.

Vasospasm-induced acute myocardial infarction-Thrombus formation without thrombogenic lesion at the culprit

Although plaque rupture is the major cause of acute myocardial infarction, vasospasm is also known as a potential cause of acute myocardial infarction. However, it is very rare and is sometimes difficult to diagnose correctly. A 30-year-old male patient with suspected unstable angina pectoris who received catheterization in 1999 had normal coronary artery but positive result in the provocation test of vasospasm. Although his angina had been suppressed by medications, he suffered ST-elevation acute myocardial infarction after the discontinuation of medication. The initial angiogram showed total occlusion of the proximal left anterior descending coronary artery. Thrombolysis and nitroglycerin achieved recanalization of the culprit lesion with only mild residual stenosis. Angioscopy revealed normal white luminal wall without any thrombogenic lesion. Therefore, the cause of coronary occlusion was diagnosed as vasospasm. However, since the repeated vasospastic occlusion of the culprit lesion regardless of repeated intra-coronary injection of nitroglycerin was observed, a stent was implanted and vasospasm was successfully prevented. It is not easy to judge from the angiogram that the cause of coronary occlusion in the patients with acute myocardial infarction is vasospasm. It is important to think routinely about the possibility of vasospasm as a cause of acute myocardial infarction. <Learning objective: In a patient with acute myocardial infarction caused by vasospasm, angioscopy revealed normal white luminal vessel wall without any thrombogenic lesion at the culprit, although the initial angiogram suggested the presence of thrombus. It is not easy to judge from the angiogram that the cause of coronary occlusion in the patients with acute myocardial infarction is vasospasm.>.

Targeting Therapy to the Fibrin-Mediated Pathophysiology of Acute Coronary Syndrome

Acute coronary syndrome (ACS) encompasses a spectrum of diseases, ranging from ST-elevation myocardial infarction to non-ST-elevation myocardial infarction and unstable angina. A key initiating event in the pathology of ACS is atheromatous plaque disruption, in which the exposure of thrombogenic material triggers simultaneous activation of primary and secondary hemostatic pathways. Targeting platelet-mediated thrombus formation with dual antiplatelet therapy comprising acetylsalicylic acid and a P2Y12 antagonist is the current mainstay for management of ACS. However, a significant proportion of patients remain at risk of cardiovascular events. Fibrin is an important contributor to thrombogenesis and may account for the residual event rates. This review examines evidence for the role of the coagulation cascade in thrombus formation in ACS, which provides a rationale for the use of anticoagulation therapy. The current status of research with novel oral anticoagulants in combination with dual antiplatelet therapy for the secondary prevention of ACS is also discussed.

Systemic and local factors associated with coronary plaque disruption

INTRODUCTION

Yellow plaques are regarded vulnerable; and disrupted yellow plaques are the major cause of acute coronary syndrome. We examined the factors associated with the disruption of yellow plaques among patients and lesion characteristics.

MATERIALS AND METHODS

Consecutive 161 patients with ischemic heart diseases who received coronary angioscopic examination were analyzed. Yellow plaques in the segments to which intervention had never been performed were included, and their yellow color grade and presence/ absence of disruption were examined. Associated factors for plaque disruption were examined among patients and lesion characteristics.

RESULTS

In 161 patients, 392 yellow plaques were included for analysis and 70 of them were disrupted. Frequency of plaque disruption (=disrupted / all yellow plaques) was significantly higher at the segments of severer stenosis (stenosis≥75% vs. 75-25% vs. <25%: 34% vs. 21% vs. 14%, p=0.006). Multivariate analysis revealed angiographic stenosis (odds ratio [OR], 1.014; 95% confidence interval [CI], 1.005-1.023; p=0.003), yellow color grade (OR, 3.297; 95% CI, 2.062-5.273, p<0.001), LDL-cholesterol (OR, 1.012; 95% CI, 1.004-1.020, p=0.003), male gender (OR, 3.608; 95% CI, 1.538-8.465; p=0.003), and hypertension (OR, 2.552; 95% CI, 1.094-5.953; p=0.030) as significant associated factors for plaque disruption.

CONCLUSION

Angiographic stenosis, yellow color grade, LDL-cholesterol, male gender, and hypertension were significantly associated with the disruption of yellow plaques.

Relationship between coronary plaque vulnerability and serum n-3/n-6 polyunsaturated fatty acid ratio

BACKGROUND

A low ratio of serum eicosapentaenoic acid to arachidonic acid (EPA/AA) has been associated with cardiovascular events. Higher-grade yellow color coronary plaques are associated with higher plaque vulnerability and higher thrombogenic potential. Therefore, the association between EPA/AA ratio and yellow color grade of coronary plaques was examined.

METHODS AND RESULTS

Consecutive patients (n=54) who underwent percutaneous coronary intervention were enrolled in this study. The serum EPA/AA ratio was examined on admission. All patients underwent an angioscopic examination of the culprit vessel to examine the color grade of yellow plaques (0, white; 1, slight yellow; 2, yellow; and 3, intense yellow) and the presence of thrombus. Excluding 16 patients with acute coronary syndrome (ACS), 38 patients with stable angina were divided into 2 groups according to their EPA/AA ratio: the low EPA/AA group (n=19, EPA/AA ratio <0.37 [median]) and the high EPA/AA group (n=19, EPA/AA ratio ≥0.37). The maximum color grade (2.5 ± 0.5 vs. 1.9 ± 0.9; P=0.01) of yellow plaques was significantly higher and the number of non-culprit yellow plaques with thrombus (1.7 ± 0.8 vs. 1.2 ± 1.1; P=0.06) tended to be higher in low EPA/AA than in high EPA/AA stable angina patients. Multivariate analysis revealed that the serum EPA level (odds ratio=0.98, 95% confidence interval=0.96-0.99, P=0.03) was associated with the presence of grade-3 yellow plaques.

CONCLUSIONS

A low serum EPA level and a low EPA/AA ratio was associated with high vulnerability of coronary plaques.

Fluffy luminal surface of the non-stenotic culprit coronary artery in patients with acute coronary syndrome: an angioscopic study

BACKGROUND

Approximately 15% of acute coronary syndrome (ACS) cases have no significant coronary stenosis. Mechanisms underlying the attacks are, however, unknown.

METHODS AND RESULTS

The clinical study had 254 patients with ACS; 38 patients (31 females and 7 males; aged 51.0 ± 8.0 years) had no significant coronary stenosis on angiography. They underwent a dye-staining angioscopy of the suspected culprit coronary artery using Evans blue, which selectively stains fibrin and damaged endothelial cells. A fluffy coronary luminal surface was observed in the suspected culprit artery in all 38 patients. The fluffy luminal surface was stained blue with Evans blue. In animal experiments involving 5 beagles, 10% hydrogen peroxide solution was injected into the iliac arteries to damage endothelial cells, which was then followed by blood reperfusion, and then the artery was examined by intravascular microscopy and histology. In the beagles, the arterial segment, where the thrombus had been formed, exhibited a fluffy luminal surface after a washout of the thrombus, and the surface was stained blue. Histologically, the fluffy surfaces were composed of damaged endothelial cells attached by multiple fibrin threads and platelets.

CONCLUSIONS

It was considered that the coronary segment exhibiting a fluffy luminal surface was the culprit lesion and that the fluffy surface was caused by residual thrombi after dispersion of an occlusive thrombus, which had formed on the damaged endothelial cells.

Visualization of lipid components in human coronary plaques using color fluorescence angioscopy

BACKGROUND

If oxidized low-density lipoprotein (oxLDL), LDL, lysophosphatidylcholine (LPC) and apolipoprotein B (apoB) can be visualized simultaneously, their roles in the initiation, progression and destabilization of atherosclerotic plaques can be objectively evaluated.

METHODS AND RESULTS

(1) The fluorescence characteristic of each atherogenic substance was investigated by microscopy using a band-pass filter (470 nm) and a band-absorption filter (520 nm) with homidium bromide (Ho) and trypan blue (TB) as indicators. (2) 50 excised human coronary plaques were classified by their autofluorescence into green, greenish-yellow and yellow, and the localization of oxLDL, LDL, LPC and apoB were investigated by color fluorescence angioscopy (CFA). The plaque colors were white, yellow and glistening yellow by conventional angioscopy. (1) OxLDL and LDL exhibited golden fluorescence, whereas LPC and apoB exhibited red fluorescence. (2) By CFA, 16 of 19 greenish-yellow and 1 of 8 yellow plaques exhibited red and golden fluorescence in a mosaic pattern, indicating co-deposition of oxLDL/LDL and LPC/apoB; 3 greenish-yellow and 7 yellow plaques exhibited red fluorescence, indicating solitary deposition of apoB; 23 green plaques infrequently exhibited these fluorescence colors.

CONCLUSIONS

OxLDL/LDL and LPC/apoB were successfully visualized as co-deposited in greenish-yellow autofluorescence plaques, but only LPC/apoB in yellow autofluorescence plaques.