Long-term ischaemic and bleeding outcomes after primary percutaneous coronary intervention for ST-elevation myocardial infarction in the elderly

Background

The population is ageing rapidly and the proportion of patients aged ≥ 80 years undergoing primary percutaneous coronary intervention (PCI) is rising, but clinical trials have primarily been performed in younger patients.

Methods

Patients undergoing primary PCI between 2003 and 2008 were subdivided into 3 groups: < 60, 60-79, and ≥ 80 years. Endpoints at 3-year follow-up included all-cause mortality, recurrent myocardial infarction (reMI), stent thrombosis, target lesion revascularisation (TLR), bleeding (BARC bleeding ≥ 3), stroke, and major adverse cardiovascular events (MACE, a composite of cardiac mortality, reMI, stroke and TLR).

Results

2002 patients with ST-segment elevation myocardial infarction (STEMI) were included, 885 (44.2 %) aged < 60, 921 (46.0 %) 60–79, and 196 (9.7 %) ≥ 80 years. Comorbidities such as diabetes mellitus, prior stroke, malignant disease, anaemia, and chronic kidney disease were more prevalent in patients ≥ 80 years. The incidence of both ischaemic and bleeding events strongly increased with age. Age ≥ 80 years was an independent predictor of mortality (HR 2.56, 95 % CI1.69–3.87, p < 0.001), a borderline non-significant predictor of overall bleeding (HR 1.38, 95 %CI 0.95–2.00, p = 0.088), and a significant predictor of non-access site bleeding (HR 2.26, 95 %CI 1.46–3.51, p < 0.001).

Conclusion

Patients ≥ 80 years experienced high rates of ischaemic and bleeding complications; especially in this high-risk patient group individualised therapy is needed to optimise clinical outcomes.

Electronic Supplementary Material

The online version of this article (doi:10.1007/s12471-015-0733-2 contains supplementary material, which is available to authorized users.     

Early versus late ST-segment resolution and clinical outcomes after percutaneous coronary intervention for acute myocardial infarction

Background. Absence of complete ST-segment resolution (STR) after percutaneous coronary intervention (PCI) for ST-segment-elevation myocardial infarction (STEMI) is a determinant of mortality. Traditionally, STR is determined on the coronary care unit (CCU) 60 to 90 minutes after the initiation of reperfusion therapy. We studied the prognostic value of STR immediately after PCI. Methods. We analysed 223 consecutive patients with STEMI and successful PCI. Continuous ECG data were collected during PCI and at 30 minutes after arrival on the CCU (mean time 81±17 minutes after reflow of the culprit artery). Patients were divided into three groups: patients with complete STR immediately after PCI (‘early’), patients with complete and persistent STR at 30 minutes on the CCU, but not immediately after PCI (‘late’) and patients without STR. One-year follow-up was obtained for death and rehospitalisation for major adverse cardiac events. Cox proportional hazards regression was used to evaluate the association between STR and outcome. Results. Early STR occurred in 115 (52%) and late STR in 43 (19%) patients. Patients with early or late STR had a lower incidence of one-year cardiac death than those without STR (1.9 vs. 9.2%; p=0.02). In contrast, rehospitalisation occurred more frequently in patients with early or late STR (20.3 vs. 6.2%; p=0.009). As compared with patients without STR, early and late STR had a similar prognostic value (hazard ratios [95% confidence interval] for cardiac death 0.40 [0.08-2.03] and 0.25 [0.03-2.08]). Conclusions. We found no (major) change in prognostic value of STR during the 0 to 90 minutes time window after PCI. (Neth Heart J 2010;18:416-22.)     

Association of admission testosterone level with ST-segment resolution in male patients with ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention

Background

Low level of testosterone may be associated with cardiovascular diseases in men, as some evidence suggests a protective role for testosterone in cardiovascular system. Little is known about the possible role of serum testosterone in response to reperfusion therapy in ST-elevation myocardial infarction (STEMI) and its relationship with ST-segment recovery. The present study was conducted to evaluate the association of serum testosterone levels with ST-segment resolution following primary percutaneous coronary intervention (PPCI) in male patients with acute STEMI.

Methods

Forty-eight men (mean age 54.55 ± 12.20) with STEMI undergoing PPCI were enrolled prospectively. Single-lead ST segment resolution in the lead with maximum baseline ST-elevation was measured and patients were divided into two groups according to the degree of ST-segment resolution: complete (> or =50%) or incomplete (<50%). The basic and demographic data of all patients, their left ventricular ejection fraction (LVEF) and laboratory findings including serum levels of free testosterone and cardiac enzymes were recorded along with angiographic finding and baseline TIMI (Thrombolysis in Myocardial Infarction) flow and also in-hospital complications and then these variables were compared between two groups.

Results

A complete ST-resolution (≥50%) was observed in 72.9% of the patients. The serum levels of free testosterone (P = 0.04), peak cardiac troponin (P = 0.03) were significantly higher and hs-CRP (P = 0.02) were lower in patients with complete ST-resolution compared to those with incomplete ST-resolution. In-hospital complications were observed in 31.2% of patients. The patients with a lower baseline TIMI flow (P = 0.03) and those who developed complications (P = 0.04) had lower levels of free testosterone. A significant positive correlation was observed between the left ventricular function and serum levels of free testosterone (P = 0.01 and r = +0.362).

Conclusion

This study suggests that in men with STEMI undergoing PPCI, higher serum levels of testosterone are associated with a better reperfusion response, fewer complications and a better left ventricular function.

     

Final benefit of primary percutaneous coronary intervention for ST-elevation myocardial infarction in older patients: long-term results of a randomised trial

Netherlands Heart Journal - Although the short-term benefit of primary percutaneous coronary intervention (PCI) in elderly patients with ST-elevation myocardial infarction (STEMI) has been...     

A 60-s postconditioning protocol by percutaneous coronary intervention inhibits myocardial apoptosis in patients with acute myocardial infarction

Different postconditioning (Postcon) methods have been demonstrated to protect heart from ischemia/reperfusion injury. The relationship between Postcon by percutaneous coronary intervention (PCI) and apoptosis is not clear. Our objective was to test whether Postcon by PCI in patients with acute myocardial infarction (AMI) reduces myocardial apoptosis. Seventy-five patients were randomly assigned to one of three groups before stenting. The Routine group (n = 26) received no Postcon intervention prior to the onset of reperfusion; Postcon-30s (n = 25) and Postcon-60s groups (n = 24) underwent three cycles of 30- or 60-s balloon deflation and 30- or 60-s inflation. Additionally, 34 normal controls (NC) were enrolled in the study. Plasma concentrations of soluble Fas/APO-1 ([sFas]) and Fas ligand ([sFasL]) were determined at baseline and 7 days after PCI via ELISA. The [sFas] and [sFasL] in AMI patients were significantly elevated at baseline as compared with NC (P < 0.01), and showed an upward trend in the Routine group, a slightly upward trend in Postcon-30s, and a downward trend in Postcon-60s at 7 days. Comparison among the three groups showed significant differences (P < 0.05, 3.8 vs. 4.6 vs. 5.1 ng ml⁻¹). The [sFasL] in Postcon-60s was significantly decreased at 7 days (P < 0.05, 3.9 vs. 3.1 ng ml⁻¹) compared with baseline, but not Postcon-30s and Routine. More importantly, Postcon-60s group had the lowest [sFasL], followed by Postcon-30s, which had a lower value than Routine at 7 days (P < 0.05, 3.1 vs.3.7 vs. 4.2 ng ml⁻¹). Our results suggest that Postcon-60s was visibly better than Postcon-30s, which in turn was better than Routine for inhibition of the effects of myocardial apoptosis and reduction of reperfusion injury in patients with acute myocardial infarction.     

Primary coronary intervention for ST-elevation myocardial infarction in Indonesia and the Netherlands: a comparison

Background. Although the beneficial effects of primary percutaneous coronary intervention (PCI) for ST-elevation myocardial infarction (STEMI) have been demonstrated in a number of trials, most studies were conducted in Western countries. Experience, logistics and patient characteristics may differ in other parts of the world. Methods. Consecutive patients treated with primary PCI in Cinere Hospital, Jakarta, Indonesia, between January 2008 and October 2008 were compared with those treated in the Isala Clinics, Zwolle, the Netherlands. Results. During the study period, a total of 596 patients were treated by primary PCI, 568 in Zwolle and 28 in Jakarta. Patients in Indonesia were younger (54 vs 63 years), more often had diabetes (36 vs. 12%) and high lipids and were more often smokers (68 vs. 31%). Time delay between symptom onset and admission was longer in Indonesia. Patients from Indonesia more often had signs of heart failure at admission. The time between admission and balloon inflation was longer in Indonesia. At angiography, patients from Indonesia more often had multivessel disease. There was no difference in the percentage of restoration of TIMI 3 flow by primary PCI between the two hospitals. Conclusion. Patients with STEMI in Indonesia have a higher risk profile compared with those in the Netherlands, according to prevalence of coronary risk factors, signs of heart failure, multivessel disease and patient delay. Time delay between admission and balloon inflation was much longer in Indonesia, because of both logistic and financial reasons. (Neth Heart J 2009;17:418–21.)     

Conditions mimicking acute ST-segment elevation myocardial infarction in patients referred for primary percutaneous coronary intervention

Background/Objectives. A rapid diagnosis of ST-segment elevation myocardial infarction (STEMI) is mandatory for optimal treatment. However, a small proportion of patients with suspected STEMI suffer from other conditions. Although case reports have described these conditions, a contemporary systematic analysis is lacking. We report the incidence, clinical characteristics and outcome of patients with suspected STEMI referred for primary percutaneous coronary intervention (PCI) with a final diagnosis other than STEMI. Methods. From January 2004 to July 2005, 820 consecutive patients were included with suspected STEMI who were referred for primary PCI to a university medical centre, based on a predefined protocol. Clinical characteristics, final diagnosis and outcome were obtained from patient charts and databases. Results. In 19 patients (2.3%), a final diagnosis other than myocardial infarction was established: coronary aneurysm (n=1), (myo)pericarditis (n=5), cardiomyopathy (n=2), Brugada syndrome (n=1), aortic stenosis (n=1), aortic dissection (n=3), subarachnoidal haemorrhage (n=2), pneumonia (n=1), chronic obstructive pulmonary disease (n=1), mediastinal tumour (n=1), and peritonitis after recent abdominal surgery (n=1). These patients less often reported previous symptoms of angina (p<0.001), smoking (p<0.05) and a positive family history of cardiovascular diseases (p<0.05) than STEMI patients. Mortality at 30 days was 16%. Conclusion. A 2.3% incidence of conditions mimicking STEMI was found in patients referred for primary PCI. A high clinical suspicion of conditions mimicking STEMI remains necessary. (Neth Heart J 2008;16:325-31.)     

Effect of primary percutaneous coronary intervention on stress hyperglycaemia in myocardial infarction

Diabet. Med. 29, 1317-1320 (2012) ABSTRACT: Aim To measure the effect of primary percutaneous coronary intervention on stress hyperglycaemia induced by ST segment elevation myocardial infarction. Methods We measured blood glucose before primary percutaneous coronary intervention and 1?h after intervention in all patients presenting with ST segment elevation myocardial infarction for 2?months in our unit. A paired t-test was used for a statistical analysis. Results From 157 patients accepted for primary percutaneous coronary intervention, 90 patients were included in the analysis. Blood glucose before intervention was 8.4?±?2.46?mmol/l (mean?±?SD) and after intervention was 7.9?±?2.0?mmol/l (mean?±?sd) (P?=?0.003). In the subset of 15 patients with hyperglycaemia (glucose greater than 10?mmol/l), glucose before intervention was 12.7?±?2.62?mmol/l (mean?±?SD) and after intervention was 9.8?±?3.42?mmol/l (mean?±?sd) (P?=?0.0002). Conclusions Blood glucose in patients with ST segment elevation myocardial infarction is significantly lower after primary percutaneous coronary intervention and this reduction is most marked in patients with hyperglycaemia. Waiting for the stress response to diminish means that 11.1% of patients' glucose levels fell below the treatment threshold of 10?mmol/l. Using the post-intervention blood glucose level avoids the need for treatment with insulin in this population. Further randomized studies are warranted to investigate the impact on mortality and morbidity of administering insulin triggered by pre-invention blood glucose vs. post-intervention blood glucose.     

The impact of adjunctive eptifibatide therapy with percutaneous coronary intervention for acute myocardial infarction

The role of small molecules anti-glycoprotein (GP) IIb/IIIa pharmacotherapy during acute myocardial infarction (AMI) has not been established. The purpose of our study was to evaluate the clinical outcomes of patients sustaining AMI who underwent emergent percutaneous coronary intervention (PCI) and who were distinguished by the use of the anti-GP IIb/IIIa agent eptifibatide. We studied a consecutive group of 216 patients who underwent PCI for acute ST-elevation myocardial infarction and compared the outcomes of patients who received eptifibatide just prior and following the procedure (n=167) to those who were not on anti GP IIb/IIIa inhibitors (n=49). On average, patients treated using eptifibatide were younger and were more likely to be men, hypertensive, and smokers. The eptifibatide treated patients were less likely to have diabetes and renal failure and had worse angiographic characteristics. There were no significant differences between the groups in any of the clinical outcomes, including the composite endpoint (e.g. death, MI, repeat revascularization) and the rate of sub-acute stent thrombosis. Nonetheless, there was a non-significant trend towards lower 30 day mortality in the eptifibatide group (4.8% versus 12%, P=0.09). We concluded that in our comparative study of periprocedural administration of eptifibatide during emergent AMI angioplasty, there was a non-significant trend towards better short-term survival among eptifibatide treated patients although the composite endpoint did not differ between patients distinguished by the use of anti GP IIb/IIIa small molecule pharmacotherapy.     

Prospective register of primary percutaneous coronary interventions in patients with acute myocardial infarction

The present study has evaluated the immediate angiographic results of primary percutaneous interventions (PCI) in patients with acute myocardial infarction, as well as hospital and 6-month clinical outcomes. The analysis covered a total of 265 patients (females (23%) and males (77%)); their mean age was 57+/-11 years. The mean time before the first balloon dilatation during PCI was 278+/-135 minutes after the development of the pain syndrome or 109+/-94 minutes after hospital admission. PCI proved to be effective in 96% of the patients, as evidenced by angiography. TIMI 3 blood flow was achieved in 83% of cases during PCI. After primary PCI, hospital mortality was 98.9% and 95% survived 6 months. At 6-month follow-up, 22% patients had positive exercise tests, recurrent angina pectoris and/or more than 50% luminal stenosis of the infarct-related artery. Control angiography made less than 6 months later showed 11% restenosis. This prospective study has demonstrated the high immediate and long effectiveness and safety of primary interventions in acute myocardial infarction.     

NGAL对直接PCI术后对比剂肾病的早期诊断价值

目的:评价NGAL在急性心肌梗死患者直接PCI术后预测CIN的诊断作用.方法:选择2009.01～2009.12我科收治的65例行直接PCI的急性心肌梗死患者,测定介入治疗前和术后8～12h、48h的血清肌酐变化情况,确定发生对比剂肾痛的患者.分别收集术前、术后8～12h血清标本置于-80℃冰箱,采用ELISA法测定各组血清中NGAL表达水平,观察术后NGAL浓度对CIN的诊断价值.结果:①145例术前肌酐正常的PCI患者,术后共有14例患者被诊断为CIN,其中研究组有8例(12.3%)、对照组有6例(7.5%)诊断为发生了CIN.②研究组中被诊断为CIN的患者术后8～12h血清NGAL的浓度与术前比较[(9.21±0.18 vs 4.05±1.30)ng/ml,p＜0.01]有显著差异,而术后8～12h Scr、BUN、GFR等指标与术前比较差异无统计学意义,血清NGAL较Scr提前至少24h诊断CIN.ROC曲线下的面积为0.851±0.052,AUC 95%的可信区间为(0.748,0.953).根据ROC曲线结果分析,NGAL预测CIN的临界点为9.04ng/ml,对应的灵敏度为78.6%,特异度为85.2%,③单变量分析示术前NGAL水平与GFR呈负相关,与Scr、BUN、舒张压(DBP)呈正相关;术后NGAL水平与GFR呈负相关,与Scr、对比剂用量呈正相关;多元Logistic回归分析显示Scr、GFR、对比剂用量是NGAL水平的独立影响因子.结论:NGAL对于AMI患者直接PCI术后发生的CIN具有良好的预测诊断作用,为早期诊断CIN提供了新思路.     

Prognostic value of rising mean platelet volume during hospitalization in patients with ST-segment elevation myocardial infarction treated with primary percutaneous coronary intervention

Background

The prognostic significance of changes in mean platelet volume (MPV) during hospitalization in ST segment elevation myocardial infarction (STEMI) patients underwent primary percutaneous coronary intervention (pPCI) has not been previously evaluated. The aim of this study was to determine the association of in-hospital changes in MPV and mortality in these patients.

Methods

Four hundred eighty consecutive STEMI patients were enrolled in this retrospective study. The patients were grouped as survivors (n?=?370) or non-survivors (n?=?110). MPV at admission, and at 48–72?h was evaluated. Change in MPV (MPV at 48–72?h minus MPV on admission) was defined as ΔMPV.

Results

At follow-up, long-term mortality was 23%. The non-survivors had a high ΔMPV than survivors (0.37 (??0.1–0.89) vs 0.79 (0.30–1.40) fL, p?<? 0.001). A high ΔMPV was an independent predictor of all cause mortality ((HR: 1.301 [1.070–1.582], p?=?0.008). Morever, for long-term mortality, the AUC of a multivariable model that included age, LVEF, Killip class, and history of stroke/TIA was 0.781 (95% CI:0.731–0.832, p?<? 0.001). When ΔMPV was added to a multivariable model, the AUC was 0.800 (95% CI: 0.750–0.848, z?=?2.256, difference p?=?0.0241, Fig. 1). Also, the addition of ΔMPV to a multivariable model was associated with a significant net reclassification improvement estimated at 24.5% (p?=?0.027) and an integrated discrimination improvement of 0.014 (p?=?0.0198).

Conclusions

Rising MPV during hospitalization in STEMI patients treated with pPCI was associated with long-term mortality.

     

Sex-specific outcomes of diabetic patients with acute myocardial infarction who have undergone percutaneous coronary intervention: a register linkage study

Background

Chronic arterial stiffness contributes to the negative health effects of obesity and insulin resistance, which include hypertension, stroke, and increased cardiovascular and all-cause mortality. Weight loss and improved insulin sensitivity are individually associated with improved central arterial stiffness; however, their combined effects on arterial stiffness are poorly understood. The purpose of this study was to determine how insulin levels modify the improvements in arterial stiffness seen with weight loss in overweight and obese young adults.

Methods

To assess the effects of weight loss and decreased fasting insulin on vascular stiffness, we studied 339 participants in the Slow the Adverse Effects of Vascular Aging (SAVE) trial. At study entry, the participants were aged 20?C45, normotensive, non-diabetic, and had a body-mass index of 25?C39.9?kg/m². Measures of pulse wave velocity (PWV) in the central (carotid-femoral (cfPWV)), peripheral (femoral-ankle (faPWV)), and mixed (brachial-ankle (baPWV)) vascular beds were collected at baseline and 6?months. The effects of 6-month change in weight and insulin on measures of PWV were estimated using multivariate regression.

Results

After adjustment for baseline risk factors and change in systolic blood pressure, 6-month weight loss and 6-month change in fasting insulin independently predicted improvement in baPWV but not faPWV or cfPWV. There was a significant interaction between 6-month weight change and change in fasting insulin when predicting changes in baPWV (p?<?0.001). Individuals experiencing both weight loss and insulin reductions showed the greatest improvement in baPWV.

Conclusions

Young adults with excess weight who both lower their insulin levels and lose weight see the greatest improvement in vascular stiffness. This improvement in vascular stiffness with weight loss and insulin declines may occur throughout the vasculature and may not be limited to individual vascular beds.

Trial registration

NCT00366990     

Predictors of ventricular tachyarrhythmia in high-risk myocardial infarction patients treated with primary coronary intervention

Background. We investigated the association between clinical characteristics, angiographic data and ventricular arrhythmia in patients with ST-elevation myocardial infarction (STEMI) treated with primary percutaneous coronary intervention (PCI) Methods. In patients with STEMI (n=225), a Holter analysis was performed the first 12 hours after primary PCI. Results. A total of 151 (66%) patients had ≥1 episode of ventricular tachycardia (VT). Age <70 years (RR 4.9, 95% CI 1.8 to 12.7), TIMI 0-1 pre-PCI (RR 2.6, 95% CI 1.1 to 6.1) and peak CK (RR 3.5, 95% CI 1.9 to 5.8) were independent predictors of VT. One-year mortality was 7%, no association between mortality and presence of early VT was found. Conclusion. Ventricular tachycardia is common in the first 12 hours after primary PCI for STEMI. Independent predictors of VT are younger age, TIMI 0-1 flow prior to PCI and larger infarct size. The presence of early VT was not significantly associated with one-year mortality. (Neth Heart J 2010;18:122-8.)     

Interpretation of elevated plasma visfatin concentrations in patients with ST-elevation myocardial infarction

Visfatin is a cytokine that is expressed in many tissues, including the heart, and has been proposed to play a role in plaque destabilization leading to acute myocardial injury. The present study evaluates plasma levels of visfatin in acute ST-elevation myocardial infarction (STEMI) patients and examines the temporal changes in visfatin levels from the acute period to the subacute period to determine a correlation with the degree of myocardial ischemia. We evaluated 54 patients with STEMI. Circulating levels of visfatin and brain natriuretic peptide (BNP) were measured by ELISA. In addition, local expression of visfatin and BNP were detected by quantitative real-time polymerase chain reaction and immunohistochemical (IHC) analysis of left ventricular myocytes in a mouse model of myocardial infarction (MI). Plasma levels of visfatin were significantly increased in patients with STEMI on admission, relative to controls (effort angina patients and individuals without coronary artery disease). The visfatin levels reached a peak 24 h after percutaneous coronary intervention (PCI) and then decreased toward the control range during the first week after PCI. The basal plasma visfatin levels were found to correlate with peak troponin-I, peak creatine kinase-MB, total white blood cell count, and BNP levels. Trend analyses confirmed that visfatin levels correlated with the number of diseased coronary arteries. Further, in MI mice, mRNA levels of visfatin and BNP were found to be higher than in sham-treated mice. IHC analysis showed that visfatin and BNP immunoreactivity was diffusely observable in left ventricular myocytes of the MI mice. This study indicates that plasma visfatin levels are significantly higher in STEMI patients and that these higher visfatin levels correlate with elevated levels of cardiac enzymes, suggesting that increased plasma visfatin may be closely related to the degree of myocardial damage.     

Sex-specific outcomes of diabetic patients with acute myocardial infarction who have undergone percutaneous coronary intervention: a register linkage study

ABSTRACT: BACKGROUND: The presence of diabetes mellitus poses a challenge in the treatment of patients with acute myocardial infarction (AMI). We aimed to evaluate the sex-specific outcomes of diabetic and non-diabetic patients with AMI who have undergone percutaneous coronary intervention (PCI). METHODS: Data of the Estonian Myocardial Infarction Registry for years 2006[EN DASH]2009 were linked with the Health Insurance Fund database and the Population Registry. Hazard ratios (HRs) with the 95 % confidence intervals (CIs) for the primary composite outcome (non-fatal AMI, revascularization, or death whichever occurred first) and for the secondary outcome (all cause mortality) were calculated comparing diabetic with non-diabetic patients by sex. RESULTS: In the final study population (n = 1652), 14.6 % of the men and 24.0 % of the women had diabetes. Overall, the diabetics had higher rates of cardiovascular risk factors, co-morbidities, and 3[EN DASH]4 vessel disease among both men and women (p < 0.01). Among women, the diabetic patients were younger, they presented later and less often with typical symptoms of chest pain than the non-diabetics (p < 0.01). Women with diabetes received aspirin and reperfusion for ST-segment elevation AMI less often than those without diabetes (p < 0.01). During a follow-up of over two years, in multivariate analysis, diabetes was associated with worse outcomes only in women: the adjusted HR for the primary outcome 1.44 (95 % CI 1.05 [MINUS SIGN] 1.96) and for the secondary outcome 1.83 (95 % CI 1.17 [MINUS SIGN] 2.89). These results were largely driven by a high (12.0 %) mortality during hospitalization of diabetic women. CONCLUSIONS: Diabetic women with AMI who have undergone PCI are a high-risk group warranting special attention in treatment strategies, especially during hospitalization. There is a need to improve the expertise to detect AMI earlier, decrease disparities in management, and find targeted PCI strategies with adjunctive antithrombotic regimes in women with diabetes.     

The emerging role of thrombus aspiration in contemporary percutaneous coronary intervention practice

Coronary atherosclerosis may lead towards thrombogenesis, usually triggered by rupture or erosion of a vulnerable epicardial coronary artery plaque. Most acute coronary syndromes are caused by ruptured atherosclerotic plaques with superimposed thrombus.