Professional guidelines recommend noninvasive cardiac testing (NIT) within 72 hours of an emergency department (ED) evaluation for suspected acute coronary syndrome. However, there is inexact evidence that this strategy reduces the risk of future death or acute myocardial infarction (MI).OBJECTIVE To evaluate the effectiveness of early NIT in reducing the risk of death or acute MI within 30 days. DESIGN, SETTING, AND PARTICIPANTSThis retrospective, multicenter cohort study within the Kaiser Permanente Southern California integrated health care delivery system compared the effectiveness of early noninvasive cardiac testing vs no testing in patients with chest pain and in whom acute MI was ruled out who presented to an ED from January 2015 to December 2017. Patients were followed up for up to 30 days after emergency department discharge.EXPOSURES Noninvasive cardiac testing performed within 3 days of an ED evaluation for suspected acute coronary syndrome. MAIN OUTCOMES AND MEASURESThe primary outcome was composite risk of death or acute MI, within 30 days of an ED discharge.RESULTS A total of 79 040 patients were evaluated in this study, of whom 57.7% were female. The mean (SD) age of the cohort was 57 (16) years, and 16 164 patients (21%) had completed early NIT. The absolute risk of death or MI within 30 days was low (<1%). Early NIT had the minor benefit of reducing the absolute composite risk of death or MI (0.4% [95% CI, −0.6% to −0.3%]), and, separately, of death (0.2% [95% CI, −0.2% to −0.1%]), MI (−0.3% [95% CI, −0.5% to −0.1%]), and major adverse cardiac event (−0.5% [95% CI, −0.7% to −0.3%]). The number needed to treat was 250 to avoid 1 death or MI, 500 to avoid 1 death, 333 to avoid 1 MI, and 200 to avoid 1 major adverse cardiovascular event within 30 days. Subgroup analysis revealed a number needed to treat of 14 to avoid 1 death or MI in the subset of patients with elevated troponin. CONCLUSIONS AND RELEVANCEEarly NIT was associated with a small decrease in the risk of death or MI in patients admitted to the ED with suspected acute coronary syndrome, but this clinical strategy may not be optimal for most patients given the large number needed to treat.

IMPORTANCE Chest pain is among the most common reasons for emergency department (ED) presentations. However, most patients are at low risk for acute coronary syndrome (ACS), with low cardiac adverse outcomes rates. Biomarker testing with troponin levels is key in the initial assessment for ACS. Although serial troponin testing can improve the diagnosis of ACS in clinical practice, some patients deemed to be low risk are discharged after a single negative troponin test result.OBJECTIVE To report the clinical outcomes of patients discharged after a single negative troponin test result compared with patients discharged after serial troponin measurements. DESIGN, SETTING, AND PARTICIPANTSThis is a retrospective cohort study of ED encounters from May 5, 2016, to December 1, 2017, across 15 community EDs within an integrated health care system in southern California. The study cohort includes 27 918 adult ED encounters in which patients were evaluated for suspected ACS with a HEART (history, electrocardiogram, age, risk factors, and troponin) score and an initial conventional troponin-I measurement below the level of detection (<0.02 ng/mL). Statistical analysis was performed from December 1, 2019, to December 1, 2020. EXPOSURE Single troponin test vs multiple troponin tests. MAIN OUTCOMES AND MEASURES The primary outcome was acute myocardial infarction or cardiac mortality; secondary outcomes included coronary artery bypass graft, percutaneous coronary intervention, invasive coronary angiography, and unstable angina within 30 days of discharge. A multivariable logistic regression model was performed to evaluate the association between testing strategies and clinical outcomes. RESULTS A total of 27 918 patient encounters (16 212 women [58.1%]; mean [SD] age, 58.7 [15.2] years) were included in the study. Of patients with an initial troponin measurement below the level of detection, 14 459 (51.8%) were discharged after a single troponin measurement, and 13 459 (48.2%) underwent serial troponin tests. After adjustment for cardiac risk factors and comorbidities, there was no statistically significant difference in the primary outcome of acute myocardial infarction or cardiac mortality within 30 days between the 2 groups (single troponin, 56 [0.4%] vs serial troponin, 52 [0.4%]; adjusted odds ratio, 1.41 [95% CI, 0.96-2.07]). Patients discharged after a single troponin test had lower rates of coronary artery bypass graft (adjusted odds ratio, 0.24 [95% CI, 0.11-0.48]) and invasive coronary angiography (adjusted odds ratio, 0.46 [95% CI, 0.38-0.56]). (continued) Key Points Question Do patients discharged from the emergency department after a single troponin test with negative results have similar outcomes to patients undergoing multiple troponin tests? Findings This cohort study found no significant difference in 30-day acute myocardial infarction or cardiac mortality between patients receiving a single troponin test with negative results and those who underwent serial troponin tests (single troponin test, 0.4% vs serial tr...

Background: Wide variation exists for hospital admission rates for the evaluation of possible acute coronary syndrome, but there are limited data on physician-level variation. Our aim is to describe physicians’ rates of admission for suspected acute coronary syndrome and associated 30-day major adverse events. Methods: We conducted a retrospective analysis of adult emergency department chest pain encounters from January 2016 to December 2017 across 15 community emergency departments within an integrated health system in Southern California. The unit of analysis was the Emergency physician. The primary outcome was the proportion of patients admitted/observed in the hospital. Secondary analysis described the 30-day incidence of death or acute myocardial infarction. Results: Thirty-eight thousand seven hundred seventy-eight patients encounters were included among 327 managing physicians. The median number of encounters per physician was 123 (interquartile range, 82–157) with an overall admission/observation rate of 14.0%. Wide variation in individual physician admission rates were observed (unadjusted, 1.5%–68.9%) and persisted after case-mix adjustments (adjusted, 5.5%–27.8%). More clinical experience was associated with a higher likelihood of hospital care. There was no difference in 30-day death or acute myocardial infarction between high- and low-admitting physician quartiles (unadjusted, 1.70% versus 0.82% and adjusted, 1.33% versus 1.29%). Conclusions: Wide variation persists in physician-level admission rates for emergency department chest pain evaluation, even in a well-integrated health system. There was no associated benefit in 30-day death or acute myocardial infarction for patients evaluated by high-admitting physicians. This suggests an additional opportunity to investigate the safe reduction of physician-level variation in the use of hospital care.

Background Noninvasive cardiac tests, including exercise treadmill tests (ETTs), are commonly utilized in the evaluation of patients in the emergency department with suspected acute coronary syndrome. However, there are ongoing debates on their clinical utility and cost‐effectiveness. It is important to be able to use ETT results for research, but manual review is prohibitively time‐consuming for large studies. We developed and validated an automated method to interpret ETT results from electronic health records. To demonstrate the algorithm's utility, we tested the associations between ETT results with 30‐day patient outcomes in a large population. Methods and Results A retrospective analysis of adult emergency department encounters resulting in an ETT within 30 days was performed. A set of randomly selected reports were double‐blind reviewed by 2 physicians to validate a natural language processing algorithm designed to categorize ETT results into normal, ischemic, nondiagnostic, and equivocal categories. Natural language processing then searched and categorized results of 5214 ETT reports. The natural language processing algorithm achieved 96.4% sensitivity and 94.8% specificity in identifying normal versus all other categories. The rates of 30‐day death or acute myocardial infarction varied ( P <0.001) by categories for normal (0.08%), ischemic (1.9%), nondiagnostic (0.77%), and equivocal (0.58%) groups achieving good discrimination (C‐statistic, 0.81; 95% CI, 0.7–0.92). Conclusions Natural language processing is an accurate and efficient strategy to facilitate large‐scale outcome studies of noninvasive cardiac tests. We found that most patients are at low risk and have normal ETT results, while those with abnormal, nondiagnostic, or equivocal results have slightly higher risks and warrant future investigation.

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