[Diagnosis of acute coronary syndrome]. / Diagnose des akuten Koronarsyndroms.

Acute coronary syndrome is one of the most important differential diagnostic considerations in emergency medicine. It describes the constellation of newly occurring clinical symptoms, often accompanied by typical 12-lead ECG changes and the release of cardiac troponins. The spectrum includes unstable angina pectoris, non-ST-segment elevation myocardial infarction (NSTEMI), and ST-segment elevation myocardial infarction (STEMI). It is important to consistently carry out the diagnostic steps that are crucial for further therapeutic procedures to avoid delaying life-saving invasive coronary diagnostics, without losing sight of the diverse, sometimes time-critical differential diagnoses. Anamnesis and clinical examination form the basis of the further procedure. Further developments of biomarker assays with personalized limit values, new imaging modalities with ever higher resolution and faster imaging methods as well as advances in automated ECG analysis with integration of all findings through artificial intelligence will continue to offer many optimization options in the future diagnosis of acute coronary syndrome.

[Treatment of Acute Coronary Syndromes]. / Therapie des akuten Koronarsyndroms.

Despite significant advances in the detection and rapid management of acute coronary syndromes (ACS), it continues to lead the cause of death statistics and they continuously represent the leading cause of death and living with disabilities, globally. Since ACS combine a spectrum of different diagnoses, a high degree of variability in possible clinical presentation and relevant gender differences, Individualised treatment is not always easy and is constantly changing due to novel evidence from research studies. Therefore, the aim of this article is therefore to explain relevant treatment options and to present the current state of science in the context of clinical patient treatment.

Characteristics of Patients With Acute Coronary Syndrome and Normal Electrocardiogram.

Background: Patients with acute coronary syndrome (ACS) and normal electrocardiogram (ECG) may have an increased risk of late diagnosis and complications of the disease. Objective: To study the demographic, angiographic and echocardiographic characteristics of patients hospitalized for ACS in whom the ECG was normal on admission to the hospital. Methods: This retrospective study included patients who were hospitalized for ACS without ST-elevation between 2015 and 2023 and who had coronary artery disease (CAD) confirmed by coronary angiography. By further inspection of the electronic databases, patients with ACS who had a normal ECG on admission were filtered out and analyzed separately. Results: Of the total 3137 patients with suspected ACS without ST-elevation, 129 patients (4.1%) were diagnosed as having ACS with a normal ECG. In three patients a non-atherosclerotic cause for the ACS was found. A significantly higher proportion of patients had single-vessel (54.3%) compared to two-vessel (29.5%) and three-vessel (14%) CAD. In addition to a normal ECG, 5.7% of patients with single-vessel CAD and 3.5% of patients with multi-vessel CAD had normal troponin levels and normal regional LV systolic function on echocardiography. Conclusion: Less than 5% of hospitalized patients with ACS without ST-elevation had a normal ECG on admission. The majority of these patients have single-vessel CAD. In about 5% of patients with single-vessel CAD, neither elevated troponin levels nor LV asynergy are detected.

Acute coronary syndrome patterns in the Young: risk factor profile and in-hospital outcomes in a tertiary referral hospital in Kenya.

INTRODUCTION: Acute coronary syndrome (ACS) accounts for coronary artery disease (CAD) -related morbidity and mortality. There has been growing concern about the rising incidence of ACS among young individuals globally both in developed and developing countries, including Sub-Saharan Africa. This group's phenotypic characteristics; risk factors and clinical outcomes are not well described. contextual and regional studies are necessary to understand the magnitude of ACS among young Individuals and help highlight challenges and opportunities for improved ACS outcomes in the region. The study aimed to describe the demographic and clinical characteristics of young individuals hospitalized with ACS and report on in-hospital outcomes. METHODOLOGY: This single-center retrospective study was conducted at the Aga Khan University Hospital, Nairobi. Medical records of all young individuals hospitalized with ACS from 30th June 2020 to 1st May 2023 were reviewed. We defined young individuals as 50 years or below. Categorical variables were reported as frequencies and proportions, and compared with Pearson chi- square or Fisher's exact tests. Continuous variables were reported as means or medians and compared with independent t-tests or Mann-Whitney U tests. P- value < 0.05 was considered statistically significant. RESULTS: Among 506 patients hospitalized with ACS, (n = 138,27.2%) were aged 50 years and below. The study population was male (n = 107, 79.9%) and African(n = 82,61.2%) predominant with a median age of 46.5 years (IQR 41.0-50.0). Hypertension (n = 101,75.4%) was noted in most study participants. More than half of the cohort were smokers (n = 69,51.5%) having a family history of premature ASCVD(n = 70,52.2%) and were on lipid-lowering therapy(n = 68,50.7%) prior to presentation. ST-segment-elevation myocardial infarction (STEMI) was the most common clinical manifestation of ACS (n = 77, 57.5%). Of the significant coronary artery disease (n = 75,56.0%), the majority of the individuals had single vessel disease (n = 60, 80%) with a predilection of left anterior deciding artery(n = 47,62.6%). The Main cause of ACS was atherosclerosis (n = 41,54.6%). The mean left ventricular ejection fraction was 46.0 (± 12.4). The in-hospital mortality was (n = 2, 1.5%). CONCLUSION: This study highlights that young individuals contribute to a relatively large proportion of patients presenting with ACS at our center. The most common presentation was STEMI. The principal cause was atherosclerosis. The findings of this study highlight the importance of developing systems of care that enable the early detection of CAD. Traditional cardiovascular risk factors were prevalent and modifiable, thus targets of intervention.

Superoxide dismutases: marker in predicting reduced left ventricular ejection fraction in patients with type 2 diabetes and acute coronary syndrome.

AIM: To examine the prognostic value of superoxide dismutase (SOD) activity for monitoring reduced left ventricular ejection fraction(LVEF)in the patients with type 2 diabetes and acute coronary syndrome (ACS). METHODS: The population of this cross-sectional study included 2377 inpatients with type 2 diabetes who had an ACS admitted to the Shandong Provincial Hospital Affiliated to Shandong First Medical University from January 2016 to January 2021. RESULTS: Diabetic patients with ACS were divided into 2 subgroups based on LVEF. The mean SOD activity was significantly lower in patients with an LVEF ≤ 45% than in those with an LVEF > 45% (149.1 (146.4, 151.9) versus 161.9 (160.8, 163.0)). Using ROC statistic, a cut-off value of 148.8 U/ml indicated an LVEF ≤ 45% with a sensitivity of 51.6% and a specificity of 73.7%. SODs activity were found to be correlated with the levels of NT-proBNP, hs-cTnT, the inflammatory marker CRP and fibrinogen. Despite taking the lowest quartile as a reference (OR 0.368, 95% CI 0.493-0.825, P = 0.001) or examining 1 normalized unit increase (OR 0.651, 95% CI 0.482-0.880, P = 0.005), SOD activity was found to be a stronger predictor of reduced LVEF than CRP and fibrinogen, independent of confounding factors. CONCLUSIONS: Our cross-sectional study suggests that SOD activity might be a valuable and easily accessible tool for assessing and monitoring reduced LVEF in the diabetic patients with ACS.

The effect of coronary stent policies on the risk of percutaneous coronary intervention among acute coronary syndrome patients in Shanghai: Real-world evidence.

OBJECTIVE: This study aimed to analyze the effect of coronary stent policies implemented in Shanghai on the risk of percutaneous coronary intervention (PCI) in acute coronary syndrome (ACS) inpatients based on real-world data. METHODS: Two retrospective cohorts of inpatients with a first diagnosis of ACS who had undergone PCI for the first time in the previous year in Shanghai hospitals were examined (one for the postpolicy period and the other for the prepolicy period). χ2 tests were used to compare categorical variables between the two cohorts. Single- and multivariate Cox proportional hazards models were used to compare the risk of major adverse cardiovascular events (MACEs) between the two cohorts. RESULTS: A total of 31,760 ACS patients were included in this study. The proportion of ACS inpatients who had at least one bid-winning stent and 3 or more coronary stents implanted for first-time PCI in the postpolicy cohort was higher than that in the prepolicy cohort (86.52% vs. 55.67% and 6.27% vs. 4.39%, respectively; all p values < 0.0001). The single- and multivariate Cox proportional hazards models revealed that the unadjusted and adjusted hazard ratios for MACEs at 1 year after PCI for the postpolicy cohort relative to the prepolicy cohort were 0.869 (P<0.0001) and 0.814 (P = 0.0007), respectively. CONCLUSIONS: The implementation of coronary stent policies changed coronary stent utilization but had no significant adverse effects on the risk of PCI among ACS patients in Shanghai in the short term. However, the reasons for changes in the number of coronary stents implanted should be analyzed and addressed in the future.

Prediabetes and major adverse cardiac events after acute coronary syndrome: An overestimated concept.

BACKGROUND: Unlike diabetes, the effect of prediabetes on outcomes in patients with acute coronary syndrome (ACS) who underwent percutaneous coronary intervention (PCI) is not much investigated. We investigated the association between fasting glycemic status and major adverse cardiovascular and cerebrovascular events (MACCE) in patients with ACS undergoing PCI and had mid to long-term follow-up after coronary stenting. METHODS: Registry-based retrospective cohort study included ACS patients who underwent PCI at the Tehran Heart Center from 2015 to 2021 with a median follow-up of 378 days. Patients were allocated into normoglycemic, prediabetic, and diabetic groups. The primary and secondary outcomes were MACCE and its components, respectively. Unadjusted and adjusted Cox models were used to evaluate the association between glycemic status and outcomes. RESULTS: Among 13 682 patients, 3151 (23%) were prediabetic, and 5834 (42.6%) were diabetic. MACCE risk was significantly higher for diabetic versus normoglycemic (adjusted hazard ratio [aHR]: 1.22, 95% confidence interval [CI]: 1.06-1.41), but nonsignificantly higher for prediabetic versus normoglycemic (aHR: 0.95, 95% CI: 0.78-1.10). All-cause mortality risk was significantly higher in diabetic versus normoglycemic (aHR: 1.42, 95% CI: 1.08-1.86), but nonsignificantly higher for prediabetic versus normoglycemic (aHR: 1.15, 95% CI: 0.84-1.59). Among other components of MACCE, only coronary artery bypass grafting was significantly higher in diabetic patients, and not prediabetic, compared with normoglycemic. CONCLUSIONS: Prediabetic ACS patients undergoing PCI, unlike diabetics, are not at increased risk of MACCE and all-cause mortality. While prediabetic patients could be regarded as having the same risk as nondiabetics, careful consideration to provide more intensive pre- and post-PCI care in diabetic patients is mandatory.

Predicting Acute Cardiovascular Complications in COVID-19: Insights from a Specialized Cardiac Referral Department.

BACKGROUND COVID-19 increases the risk of acute cardiovascular diseases (CVDs), including acute coronary syndrome (ACS), acute pulmonary embolism (APE), and acute myocarditis (AMyo). The actual impact of CVDs on mortality of patients with COVID-19 remains unknown. This study aimed to determine whether CVDs influence the course of COVID-19 pneumonia and if they can be easily detected by using common tests and examinations. MATERIAL AND METHODS Data of 249 consecutive patients with COVID-19 hospitalized in a dedicated cardiology department were analyzed. On admission, clinical status, biomarkers, computed tomography, and bedside echocardiography were performed. RESULTS D-dimer level predicted APE (AUC=0.850 95% CI [0.765; 0.935], P<0.001) with sensitivity of 69.4% and specificity of 96.2% for a level of 4968.0 ng/mL, and NT-proBNP predicted AMyo (AUC=0.692 95% CI [0.502; 0.883], P=0.004) and showed sensitivity of 54.5%, with specificity of 86.5% for the cut-off point of 8970 pg/mL. Troponin T levels were not useful for diagnostic differentiation between CVDs. An extent of lung involvement predicted mortality (OR=1.03 95% CI [1.01;1.04] for 1% increase, P<0.001). After adjusting for lung involvement, ACS increased mortality, compared with COVID-19 pneumonia only (OR=5.27 95% CI [1.76; 16.38] P=0.003), while APE and AMyo did not affect risk for death. CONCLUSIONS D-dimer and NT-proBNP, but not troponin T, are useful in differentiating CVDs in patients with COVID-19. ACS with COVID-19 increased in-hospital mortality independently from extent of lung involvement, while coexisting APE or AMyo did not.

Comparison of troponin and natriuretic peptides in Takotsubo syndrome and acute coronary syndrome: a meta-analysis.

OBJECTIVE: Takotsubo syndrome (TTS) is an acute heart failure syndrome which resembles acute coronary syndrome (ACS) at presentation. Differentiation requires coronary angiography, but where this does not occur immediately, cardiac biomarkers may provide additional utility. We performed a meta-analysis to compare troponin and natriuretic peptides (NPs) in TTS and ACS to determine if differences in biomarker profile can aid diagnosis. METHODS: We searched five literature databases for studies reporting NPs (Brain NP (BNP)/NT-pro-BNP) or troponin I/T in TTS and ACS, identifying 28 studies for troponin/NPs (5618 and 1145 patients, respectively). RESULTS: Troponin was significantly lower in TTS than ACS (standardised mean difference (SMD) -0.86; 95% CI, -1.08 to -0.64; p<0.00001), with an absolute difference of 75 times the upper limit of normal (×ULN) higher in ACS than TTS. Conversely, NPs were significantly higher in TTS (SMD 0.62; 95% CI, 0.44 to 0.80; p<0.00001) and 5.8×ULN greater absolutely. Area under the curve (AUC) for troponin in ACS versus TTS was 0.82 (95% CI, 0.70 to 0.93), and 0.92 (95% CI, 0.80 to 1.00) for ST-segment elevation myocardial infarction versus TTS. For NPs, AUC was 0.69 (95% CI, 0.48 to 0.89). Combination of troponin and NPs with logistic regression did not improve AUC. Recursive Partitioning and Regression Tree analysis calculated a troponin threshold ≥26×ULN that identified 95% cases as ACS where and specificity for ACS were 85.71% and 53.57%, respectively, with 94.32% positive predictive value and 29.40% negative predictive value. CONCLUSIONS: Troponin is lower and NPs higher in TTS versus ACS. Troponin had greater power than NPs at discriminating TTS and ACS, and with troponin ≥26×ULN patients are far more likely to have ACS.

[Value of cardiodynamicsgram in early diagnosis of patients with acute coronary syndrome].

OBJECTIVE: To explore the value of cardiodynamicsgram (CDG) obtained from electrocardiogram (ECG) data by radial basis functionradial basis function (RBF) neural network in early diagnosis of patients with acute coronary syndrome (ACS). METHODS: Retrospective analysis method was used. Patients with chest pain as the main initial symptom in the emergency department of Baoan District People's Hospital of Shenzhen from October 2021 to September 2022 were enrolled. Baseline data were collected, including gender, age, smoking history, family history of coronary heart disease and history of hypertension, diabetes, hyperlipidemia, and atherosclerosis. The first 12-lead ECG was recorded after admission to the emergency department, and electrocardiodynamics analysis was performed to generate CDG. Receiver operator characteristic curve (ROC curve) was plotted to analyze the value of CDG and ECG in the early diagnosis of ACS and non-ST segment elevation ACS (NSTE-ACS). Sensitivity, specificity, area under the ROC curve (AUC), and 95% confidence interval (95%CI) were calculated. CDG and coronary angiography results of 3 patients with ACS with normal ECG were observed and analyzed. Non-ACS patients with normal ECG but positive CDG were followed for 30 days for adverse cardiovascular events. RESULTS: A total of 384 patients with chest pain were included, including 169 patients with ACS and 215 patients without ACS. The proportion of male (87.0% vs. 53.0%), smoking history (37.9% vs. 12.1%), hypertension (46.2% vs. 22.3%), diabetes (24.3% vs. 7.9%), hyperlipidemia (55.0% vs. 14.0%) and history of atherosclerosis (22.5% vs. 2.3%) in ACS group were significantly higher than those in non-ACS group (all P < 0.05). The ROC curve showed that the AUC of CDG diagnosis of ACS was higher than that of ECG [AUC (95%CI): 0.88 (0.66-0.76) vs. 0.71 (0.84-0.92)], the sensitivity was 92.8%, 78.6%, and the specificity was 83.3%, 64.2%, respectively. The AUC of CDG diagnosis of NSTE-ACS was higher than that of ECG [AUC (95%CI): 0.85 (0.80-0.90) vs. 0.63 (0.56-0.69)], the sensitivity was 87.1%, 61.3%, and the specificity was 83.3%, 64.2%, respectively. CDG of 3 patients with ACS with normal ECG showed disordered state, and coronary angiography showed ≥70% stenosis of major coronary branches. Of 215 non-ACS patients, 20 had a normal ECG but positive CDG, and 3 developed ST segment elevation myocardial infarction (STEMI) within 30 days, and 2 developed unstable angina (UA) within 30 days. CONCLUSIONS: CDG has high value in early diagnosis of ACS patients and is expected to become an important means of early diagnosis of ACS in emergency.

The CRP troponin test (CTT) stratifies mortality risk in patients with non-ST elevation myocardial infarction (NSTEMI).

INTRODUCTION: The C-reactive protein (CRP)-troponin-test (CTT) comprises simultaneous serial measurements of CRP and cardiac troponin and might reflect the systemic inflammatory response in patients with acute coronary syndrome. We sought to test its ability to stratify the short- and long-term mortality risk in patients with non-ST elevation myocardial infarction (NSTEMI). METHODS: We examined 1,675 patients diagnosed with NSTEMI on discharge who had at least two successive measurements of combined CRP and cardiac troponin within 48 h of admission. A tree classifier model determined which measurements and cutoffs could be used to best predict mortality during a median follow-up of 3 years [IQR 1.8-4.3]. RESULTS: Patients with high CRP levels ( > 90th percentile, >54 mg/L) had a higher 30-day mortality rate regardless of their troponin test findings (16.7% vs. 2.9%, p < 0.01). However, among patients with "normal" CRP levels ( < 54 mg/L), those who had high troponin levels ( > 80th percentile, 4,918 ng/L) had a higher 30-day mortality rate than patients with normal CRP and troponin concentrations (7% vs. 2%, p < 0.01). The CTT test result was an independent predictor for overall mortality even after adjusting for age, sex, and comorbidities (HR = 2.28 [95% CI 1.56-3.37], p < 0.01 for patients with high troponin and high CRP levels). CONCLUSIONS: Early serial CTT results may stratify mortality risk in patients with NSTEMI, especially those with "normal" CRP levels. The CTT could potentially assess the impact of inflammation during myocardial necrosis on the outcomes of patients with NSTEMI and identify patients who could benefit from novel anti-inflammatory therapies.

Sex differences in patients presenting with acute coronary syndrome: a state-of-the-art review.

Cardiovascular conditions in the spectrum of acute coronary syndromes are characterized by sex differences with regard to pathophysiology, risk factors, clinical presentation, invasive and pharmacologic treatment, and outcomes. This review delves into these differences, including specific subsets like myocardial infarction with non-obstructed coronary arteries or Spontaneous Coronary Artery Dissection, and alternative diagnoses like Takotsubo cardiomyopathy or myocarditis. Moreover, practical considerations are enclosed, on how a sex-specific approach should be integrated in clinical practice: in fact, personal history should focus on female-specific risk factors, and hormonal status and hormonal therapy should be assessed. Moreover, physical and psychological stressors should be investigated, particularly in the event of Spontaneous Coronary Artery Dissection or Takotsubo cardiomyopathy.

Early SGLT2 inhibitor use is associated with improved left atrial strain following acute coronary syndrome.

AIM: Left atrial (LA) strain, a novel marker of LA function, reliably predicts diastolic dysfunction. SGLT2 inhibitors improve heart failure outcomes, but limited data exists regarding their use in the immediate aftermath of acute coronary syndrome (ACS). We studied the effect of empagliflozin on LA strain in patients with type 2 diabetes (T2D) and ACS. METHODS: Patients with ACS and T2D were identified and empagliflozin was initiated in eligible patients prior to discharge. Patients not initiated on empagliflozin were analysed as a comparator group. A blinded investigator assessed LA strain using baseline and 3-6 month follow-up echocardiograms. RESULTS: Forty-four participants (n = 22 each group) were included. Baseline characteristics and LA strain were similar in the two groups. LA reservoir, conduit and contractile strain increased in empagliflozin group (28.0 ± 8.4% to 34.6 ± 12.2% p < 0.001, 14.5 ± 5.4% to 16.7 ± 7.0% p = 0.034, 13.5 ± 5.2% to 17.9 ± 7.2% p = 0.005, respectively) but remained unchanged in comparison group (29.2 ± 6.7% to 28.8 ± 7.0%, 12.8 ± 4.2% to 13.3 ± 4.7%, 16.7 ± 5.3% to 15.5 ± 4.5%, respectively, p = NS). The difference in change between groups was significant for LA reservoir (p = 0.003) and contractile strain (p = 0.005). CONCLUSION: In patients with ACS and T2D, addition of empagliflozin to standard ACS therapy prior to discharge is associated with improved LA function.

Obstructive myocardial infarction with normal automated ECG interpretation: A case report.

Emergency Medicine physicians experience a significant number of interruptions throughout their work day. One common cause of interruptions is the immediate interpretation of triage electrocardiograms (ECGs). Recent studies have suggested that ECGs interpreted as normal via automated analysis by the ECG machine rarely require urgent cardiac intervention and suggested that providers may not have to be interrupted to interpret these "normal" ECGs. We describe the case of a patient who presented to the Emergency Department (ED) with chest pain and an ECG interpreted as normal by an automated reading from the ECG machine, despite having acute coronary syndrome requiring emergent intervention.

Temporal trends in admission for cardiac rehabilitation after an acute coronary syndrome in France from 2009 to 2021: Persistent sex, age and social disparities.

BACKGROUND: Cardiac rehabilitation after an acute coronary syndrome is recommended to decrease patient morbidity and mortality and to improve quality of life. AIMS: To describe time trends in the rates of patients undergoing cardiac rehabilitation after an acute coronary syndrome in France from 2009 to 2021, and to identify possible disparities. METHODS: All patients hospitalized for acute coronary syndrome in France between January 2009 and June 2021 were identified from the national health insurance database. Cardiac rehabilitation attendance was identified within 6 months of acute coronary syndrome hospital discharge. Age-standardized cardiac rehabilitation rates were computed and stratified for sex and acute coronary syndrome subtypes (ST-segment elevation and non-ST-segment elevation). Patient characteristics and outcomes were described and compared. Factors independently associated with cardiac rehabilitation attendance were identified. RESULTS: In 2019, among 134,846 patients with an acute coronary syndrome, 22.3% underwent cardiac rehabilitation within 6 months of acute coronary syndrome hospital discharge. The mean age of patients receiving cardiac rehabilitation was 62 years. The median delay between acute coronary syndrome hospitalization and cardiac rehabilitation was 32 days, with about 60% receiving outpatient cardiac rehabilitation. Factors significantly associated with higher cardiac rehabilitation rates were male sex, younger age (35-64 years), least socially disadvantaged group, ST-segment elevation, percutaneous coronary intervention and coronary artery bypass graft. Between 2009 and 2019, cardiac rehabilitation rates increased by 40% from 15.9% to 22.3%. Despite greater upward trends in women, their cardiac rehabilitation rate was significantly lower than that for men (14.8% vs. 25.8%). In 2020, cardiac rehabilitation attendance dropped because of the coronavirus disease 2019 pandemic. CONCLUSIONS: Despite the health benefits of cardiac rehabilitation, current cardiac rehabilitation attendance after acute coronary syndrome remains insufficient in France, particularly among the elderly, women and socially disadvantaged people.

Validation of the ACC Expert Consensus Decision Pathway for Patients With Chest Pain.

BACKGROUND: The American College of Cardiology (ACC) recently published an Expert Consensus Decision Pathway for chest pain. OBJECTIVES: The purpose of this study was to validate the ACC Pathway in a multisite U.S. METHODS: An observational cohort study of adults with possible acute coronary syndrome was conducted. Patients were accrued from 5 U.S. Emergency Departments (November 1, 2020, to July 31, 2022). ECGs and 0- and 2-hour high-sensitivity troponin (Beckman Coulter) measures were used to stratify patients according to the ACC Pathway. The primary safety outcome was 30-day all-cause death or myocardial infarction (MI). Efficacy was defined as the proportion stratified to the rule-out zone. Negative predictive value for 30-day death or MI was assessed among the whole cohort and in a subgroup of patients with coronary artery disease (CAD) (prior MI, revascularization, or ≥70% coronary stenosis). RESULTS: ACC Pathway assessments were complete in 14,395 patients, of whom 51.7% (7,437 of 14,395) were women with a median age of 56 years (Q1-Q3: 44-68 years). Known CAD was present in 23.5% (3,386 of 14,395) and 30-day death or MI occurred in 8.1% (1,168 of 14,395). The ACC Pathway had an efficacy of 48.1% (95% CI: 47.3%-49.0%). Among patients in the rule-out zone, 0.3% (22 of 6,930) had death or MI at 30 days, yielding a negative predictive value of 99.7% (95% CI: 99.5%-99.8%). In patients with known CAD, 20.0% (676 of 3,386) were classified to the rule-out zone, of whom 1.5% (10 of 676) had death or MI. CONCLUSIONS: The ACC expert consensus decision pathway was safe and efficacious. However, it may not be safe for use among patients with known CAD.