Predictors of major adverse cardiac events among patients with chest pain and low HEART score in the emergency department.

AIM: For patients who present to the emergency departments (ED) with undifferentiated chest pain, the risk of major adverse cardiac events (MACE) may be underestimated in low-HEART score patients. We aimed to identify characteristics of patients who were classified as low risk by HEART score but subsequently developed MACE at 6 weeks. METHODS: We studied a multiethnic cohort of patients who presented with chest pain arousing suspicion of acute coronary syndrome to EDs in the Netherlands and Singapore. Patients were risk-stratified using HEART score and followed up for MACE at 6 weeks. Risk factors of developing MACE despite low HEART scores (scores 0-3) were identified using logistic and Cox regression models. RESULTS: Among 1376 (39.8%) patients with low HEART scores, 63 (4.6%) developed MACE at 6 weeks. More males (53/806, 6.6%) than females (10/570, 2.8%) with low HEART score developed MACE. There was no difference in outcomes between ethnic groups. Among low-HEART score patients with 2 points for history, 21% developed MACE. Among low-HEART score patients with 1 point for troponin, 50% developed MACE, while 100% of those with 2 points for troponin developed MACE. After adjusting for HEART score and potential confounders, male sex was independently associated with increased odds (OR 4.12, 95%CI 2.14-8.78) and hazards (HR 3.93, 95%CI 1.98-7.79) of developing MACE despite low HEART score. CONCLUSION: Male sex, highly suspicious history and elevated troponin were disproportionately associated with MACE. These characteristics should prompt clinicians to consider further investigation before discharge.

HEART score performance in Asian and Caucasian patients presenting to the emergency department with suspected acute coronary syndrome.

BACKGROUND: The HEART score is a simple and effective tool to predict short-term major adverse cardiovascular events in patients suspected of acute coronary syndrome. Patients are assigned to three risk categories using History, ECG, Age, Risk factors and Troponin (HEART). The purpose is early rule out and discharge is considered safe for patients in the low risk category. Its performance in patients of Asian ethnicity is unknown. We evaluated the performance of the HEART score in patients of Caucasian, Chinese, Indian and Malay ethnicity. METHODS: The HEART score was assessed retrospectively in 3456 patients presenting to the emergency department with suspected acute coronary syndrome (1791 Caucasians, 1059 Chinese, 344 Indians, 262 Malays), assigning them into three risk categories. RESULTS: The incidence of major adverse cardiovascular events within six weeks after presentation was similar between the ethnic groups. A smaller proportion of Caucasians was in the low risk category compared with Asians (Caucasians 35.8%, Chinese 43.5%, Indians 45.3%, Malays 44.7%, p<0.001). The negative predictive value of a low HEART score was comparable across the ethnic groups, but lower than previously reported (Caucasians 95.3%, Chinese 95.0%, Indians 96.2%, Malays 96.6%). Also the c-statistic for the HEART score was not significantly different between the groups. CONCLUSIONS: These results show that the overall performance of the HEART score is equal among Caucasian and Asian ethnic groups. The event rate in the low risk group, however, was higher than reported in previous studies, which queries the safety of early discharge of patients in the low risk category.

Sex-Based Differences in the Performance of the HEART Score in Patients Presenting to the Emergency Department With Acute Chest Pain.

BACKGROUND: Sex-based differences in clinical presentation, pathophysiology, and outcomes of patients with acute chest pain are increasingly being recognized, but are not implemented in guidelines and clinical prediction tools. We evaluated the performance of the HEART score in women versus men, because sex-based differences may exist among the algorithm's components: history, electrocardiogram, age, risk factors, and admission troponin level. METHODS AND RESULTS: The HEART score was retrospectively assessed in 831 women and 1084 men presenting to the emergency department with acute chest pain, assigning patients to the low-, intermediate-, or high-risk category for the occurrence of major adverse cardiac events (MACE) within 6 weeks. MACE, consisting of myocardial infarction, coronary revascularization, and all-cause death, also included events during index visit. Six-week MACE rates were 2 times lower in women than men (10.0% versus 20.8%; P<0.01). Despite similar discriminatory accuracy of the HEART score among women and men (c-statistic, 0.80 [0.75-0.84] versus 0.77 [0.74-0.81]; P=0.43), 6-week MACE rates were significantly lower in women than men across all HEART risk categories: 2.1% versus 6.5% (P<0.01) in the low-risk category, 12.7% versus 21.3% (P<0.01) in intermediate-risk category, and 53.1% versus 77.0% (P=0.02) in the high-risk category. The HEART score-adjusted risk ratio for men was 1.6 (1.3-2.0; P<0.01). CONCLUSIONS: The markedly higher 6-week MACE risk in men across all HEART risk categories should be taken into account when using the HEART score to guide clinical decision making; early discharge with a low-risk HEART score appears less safe for men than women with acute chest pain.

Ethnic differences in clinical outcome of patients presenting to the emergency department with chest pain.

BACKGROUND: Ethnicity, although known to influence cardiovascular outcome in assorted clinical settings, has not been investigated previously as a risk factor in patients presenting to the emergency department with suspected acute myocardial infarction. METHODS: In this multi-ethnic cohort study conducted in Singapore and The Netherlands, 2784 patients presenting to the emergency department with chest pain were enrolled (788 Caucasians, 1281 Chinese, 404 Indians and 311 Malays) and were followed up for 1 year. RESULTS: Although Caucasian patients on average were older and had incurred more cardiovascular adverse events, the Asian ethnic groups carried a greater burden of cardiovascular risk factors. Caucasian and Malay patients were most frequently diagnosed with acute myocardial infarction (Caucasians 11.2%, Chinese and Indians 6.4%, Malays 10.6%, P<0.001), also after correction for baseline differences. Chinese and Indian patients, however, more often had unstable angina. Asian patients had strikingly more extensive coronary artery disease than Caucasian patients (triple-vessel disease: Caucasians 6.5%, Chinese 22.8%, Indians 32.4%, Malays 32.8%, P<0.001) and Chinese patients with myocardial infarction more frequently underwent coronary revascularisation compared with Caucasian patients (Caucasians 41.4%, Chinese 67.5%, Indians 62.5%, Malay 46.7%, P=0.005). Ethnicity was not an independent predictor of major adverse cardiovascular events during 1-year follow-up in all chest pain patients. CONCLUSIONS: The prevalence of myocardial infarction and unstable angina, revascularisation rate and extent of coronary artery disease differ significantly among chest pain patients of different ethnic groups. These findings have important clinical implications and support consideration of ethnicity in risk stratification and determination of the patient management strategy in patients with symptoms suggestive of myocardial infarction.

BLT1 antagonist LSN2792613 reduces infarct size in a mouse model of myocardial ischaemia-reperfusion injury.

AIMS: Restoration of coronary blood flow is crucial in the treatment of acute myocardial infarction. Reperfusion, however, induces ischaemia-reperfusion (IR) injury, which further deteriorates myocardial function. The innate immune system plays an important role in this process, mediating rapid influx of immune cells into the reperfused myocardium. Leukotriene B4 is an important leucocyte chemoattractant, performing its actions through binding to its specific receptor BLT1. We hypothesized that treatment with LSN2792613, a selective BLT1 antagonist, reduces infarct size (IS) in a mouse model of myocardial IR injury. METHODS AND RESULTS: Male C57Bl/6J mice were subjected to myocardial ischaemia for 30 min by surgical coronary artery ligation, followed by reperfusion. Mice received either LSN2792613 or vehicle, three times daily (orally) for up to 72 h after reperfusion. BLT1 inhibition with LSN2792613 reduced IS compared with vehicle treatment (26.9 ± 2.7 vs. 34.9 ± 2.2%, P = 0.030) at 24 h after reperfusion. The levels of IL-6 and keratinocyte chemoattractant were reduced in the infarcted tissue of LSN2792613-treated mice. Reduced apoptosis in LSN2792613-treated mice was suggested by increased levels of phosphorylated JNK and GSK3α/ß, and confirmed by flow cytometric analysis showing less apoptotic and necrotic cardiomyocytes in the infarcted myocardium. Echocardiography at 4 weeks after myocardial IR showed a slightly higher ejection fraction and stroke volume in mice treated with LSN2792613 compared with vehicle-treated mice, whereas left ventricular volumes were comparable. CONCLUSION: Selective BLT1 inhibition with LSN2792613 reduces inflammation and apoptosis following IR, resulting in reduced IS, and therefore might be a promising strategy to prevent myocardial IR injury.

Leucocyte expression of complement C5a receptors exacerbates infarct size after myocardial reperfusion injury.

AIMS: Early reperfusion is mandatory for the treatment of acute myocardial infarction. This process, however, also induces additional loss of viable myocardium, called ischaemia-reperfusion (IR) injury. Complement activation plays an important role in IR injury, partly through binding of C5a to its major receptor (C5aR). We investigated the role of C5aR on infarct size and cardiac function in a model for myocardial IR injury. METHODS AND RESULTS: BALB/c (WT) mice and C5aR(-/-) mice underwent coronary occlusion for 30 min, followed by reperfusion. Infarct size, determined 24 h after IR, was reduced in C5aR(-/-) mice compared with WT mice (28.5 ± 2.1 vs. 35.7 ± 2.5%, P = 0.017). Bone marrow (BM) chimaera experiments showed that this effect was due to the absence of C5aR on circulating leucocytes, since a similar reduction in infarct size was observed in WT mice with C5aR-deficient BM cells (25.3 ± 2.2 vs. 34.6 ± 2.8%, P < 0.05), but not in C5aR(-/-) mice with WT BM cells. Reduced infarct size was associated with fewer neutrophils, T cells, and macrophages in the infarcted area 24 h after IR in C5aR(-/-) mice, and also with lower levels of Caspase-3/7 indicating less inflammation and apoptosis. Echocardiography 4 weeks after IR showed an improved ejection fraction in C5aR(-/-) mice (25.8 ± 5.5 vs. 19.2 ± 5.4%, P < 0.001). CONCLUSION: The absence of C5aR on circulating leucocytes reduces infarct size, is associated with reduced leucocyte infiltration and with less apoptosis in the infarcted myocardium, and improves cardiac function in a mouse model of myocardial IR injury. Selective blocking of C5aR might be a promising strategy to prevent myocardial IR injury.

Serum extracellular vesicle protein levels are associated with acute coronary syndrome.

AIMS: Biomarkers are essential in the early detection of acute coronary syndromes (ACS). Serum extracellular vesicles are small vesicles in the plasma containing protein and RNA and have been shown to be involved in ACS-related processes like apoptosis and coagulation. Therefore, we hypothesized that serum extracellular vesicle protein levels are associated with ACS. METHODS AND RESULTS: Three serum extracellular vesicle proteins potentially associated with ACS were identified with differential Q-proteomics and were evaluated in 471 frozen serum samples of ACS-suspected patients presenting to the emergency department (30% of whom had an ACS). Protein levels were measured after vesicle isolation using ExoQuick. Mean serum extracellular vesicle concentration of the different proteins was compared between ACS and non-ACS patients. Selected proteins were tested in a univariate logistic regression model, as well as in a multivariate model to adjust for cardiovascular risk factors. A separate analysis was performed in men and women. In the multivariate logistic regression analysis, polygenic immunoglobulin receptor, (pIgR; OR 1.630, p=0.026), cystatin C (OR 1.641, p=0.021), and complement factor C5a (C5a, OR 1.495, p=0.025) were significantly associated with ACS, while total vesicle protein concentration was borderline significant. The association of the individual proteins with ACS was markedly stronger in men. CONCLUSIONS: These data show that serum extracellular vesicle pIgR, cystatin C, and C5a concentrations are independently associated with ACS and that there are pronounced gender differences. These observations should be validated in a large, prospective study to assess the potential role of vesicle content in the evaluation of patients suspected of having an ACS.

The innate immune response in reperfused myocardium.

One of the major therapeutic challenges in the arena of interventional cardiology is to design strategies aimed at reducing myocardial tissue damage after myocardial infarction. In response to tissue injury, an innate immune response is initiated that orchestrates homeostatic responses and is a prerequisite for subsequent wound healing. An exaggerated inflammatory reaction, however, countervenes these beneficial effects and contributes to maladaptive tissue damage. Herein, we discuss the pathways involving the innate immune system that have been investigated in the setting of myocardial ischaemia and reperfusion injury. Endogenous 'danger' signals [danger-associated molecular patterns (DAMPs)] are expressed following tissue injury and alert the innate immune system. Toll-like receptors and the complement system are activated, resulting in an inflammatory reaction involving inflammatory cell influx and the production and release of inflammatory cytokines. A potential involvement of cell-derived microparticles in the modulation of the innate immune response following myocardial injury will also be discussed. Our future challenge lies within the counteraction of maladaptive inflammatory cascades, without interfering in the benign wound healing response, and in translating these anti-inflammatory strategies into clinical practice.