Guide - Emergency Medicine



Objectives: "This study evaluated 5 accelerated diagnostic pathways for the assessment of patients with symptoms suggestive of acute coronary syndrome: the HEART pathway, m-ADAPT, the EDACS pathway, the new Vancouver Chest Pain Rule, and the No Objective Testing Rule. The aim of this study was to evaluate the diagnostic performance of each of these scores when calculated with the new Access hs-TnI assay taken at 0 and 2 hours after presentation." (p. 440)

Methods: This retrospective, observational study utilized data from two previous prospective studies, both conducted at the same tertiary hospital in Australia (the ADAPT study, conducted between November 2008 and February 2011, and the Improved Assessment of Chest Pain Trial, conducted between February 2011 and March 2014). Patients were recruited between 8 AM to 5 PM, and were eligible if they were adults (18 years or older) presenting with 5 or more minutes of chest pain and were undergoing investigation of potential acute coronary syndrome. Exclusion criteria were clear alternative cause for symptoms, inability or unwillingness to provide consent, "recruitment was considered inappropriate (eg, palliative treatment)," pregnancy, recruitment into the study within 45 days prior, transfer from another hospital, inability to contact after discharge (eg, homeless), or presence of criteria for ST-segment elevation MI on presentation.

ECGs and blood samples were obtained on presentation and at 2 hours. Blood samples were later analyzed by Access hs-TnI assay in a blinded fashion. Follow-up occurred thirty days following presentation via telephone follow-up and medical record review. Patients were retrospectively classified as "low risk" or "not low risk" according to the m-ADAPT, EDACS, HEART, new Vancouver Chest Pain Rule, and No Objective Testing Rule clinical decision rules. For the m-ADAPT and EDACS scores, the primary outcome was 30-day acute myocardial infarction (determined by death from a cardiac cause, a diagnosis of NSTEMI or STEMI, or need for emergency revascularization during admission or within 30 days). For the HEART score, new Vancouver Chest Pain Rule, and No Objective Testing Rule, the outcome was 30-day acute coronary syndrome (defined by the same criteria for acute MI, plus need for unplanned revascularization or unstable angina pectoris during admission or within 30 days). Outcomes were assigned by a cardiologist, with a blind review by a second cardiologist of all patients assigned a cardiovascular endpoint and 10% of cases with a noncardiovascular endpoint. Disagreement was resolved by consensus of the two cardiologists and an emergency physician. Outcomes were assigned based on conventional troponin I measures (and NOT based on hs-cTnI) without the results of any of the clinical decision rules.

A total of 1811 patients were recruited in the two studies and included in this analysis. The mean age was 52.9 years and 60% were male. Acute MI within 30 days was ultimately diagnosed in 5.3% of the population while acute coronary syndrome was diagnosed in 7.7% of the population.

|Guide |Comments |

|I. |Are the results valid? | |

|A. |Did clinicians face diagnostic uncertainty? |Yes. Patients presenting to the ED with chest pain or other symptoms concerning for |

| | |possible AMI were included. While some of these patients ruled in for AMI, many were|

| | |eventually diagnosed with non-cardiac causes of chest pain. |

|B. |Was there a blind comparison with an |Not entirely. While there is no single gold standard for diagnosis of myocardial |

| |independent gold standard applied similarly |infarction or acute coronary syndrome, the authors used an adjudicated final |

| |to all patients? |diagnosis as the reference criterion in this study. The authors specifically note |

| | |that cardiologists used the conventional (rather than high sensitivity) troponin |

| |(Confirmation Bias) |assays to make their diagnosis, but even using conventional assays the inclusion of |

| | |troponin measurements put the study at risk of incorporation bias. |

|C. |Did the results of the test being evaluated |Not specifically. Again, there was no true gold standard in this study, and |

| |influence the decision to perform the gold |adjudicated diagnosis was used as the reference criterion. While details were not |

| |standard? |provided, it is likely that the results of cardiac enzyme testing and possibly the |

| |(Ascertainment Bias) |clinical decision rules being evaluated influenced decisions about further testing, |

| | |to include cardiac stress testing and cardiac catheterizations, which could have |

| | |influenced the final adjudicated diagnoses, hence leading to differential and |

| | |partial verification bias. |

|II. |What are the results? | |

|A. |What likelihood ratios were associated with | |

| |the range of possible test results? | |

| | |NPV |

| | |LR- |

| | |LR+ |

| | | |

| | |m-ADAPT pathway |

| | |99.7% |

| | |(95% CI 99.2-99.9%) |

| | |0.05 |

| | |3.01 |

| | | |

| | |EDACS pathway |

| | |99.8% |

| | |(95% CI 99.4-100%) |

| | |0.03 |

| | |2.87 |

| | | |

| | |HEART pathway |

| | |99.8% |

| | |(95% CI 99.2-100%) |

| | |0.04 |

| | |2.06 |

| | | |

| | |Vancouver Chest Pain pathway |

| | |100% |

| | |(95% CI 99.3-100%) |

| | |0 |

| | |1.42 |

| | | |

| | |NOT rule pathway |

| | |100% |

| | |(95% CI 99.4-100%) |

| | |0 |

| | |1.57 |

| | | |

| | | |

| | |The negative predictive values and likelihood ratios associated with the 5 pathways |

| | |is provided in the table above. |

|III. |How can I apply the results to patient care? | |

|A. |Will the reproducibility of the test result |Yes. The hs-cTnI assay used in this study is widely available and the algorithms |

| |and its interpretation be satisfactory in my |used to diagnose AMI could easily be used in our institution, and the clinical |

| |clinical setting? |decision rules are easy to use and widely available. |

|B. |Are the results applicable to the patients in|Yes. We routinely provide care for patients with undifferentiated chest pain. Use of|

| |my practice? |clinical decision pathways involving high sensitivity troponin assays to decreased |

| | |ED length of stay and prevent unnecessary hospital admissions and further testing |

| | |would be worthwhile to both decrease ED/hospital overcrowding and improve patient |

| | |satisfaction. |

|C. |Will the results change my management |Likely yes. We are in the process of switching over to a hs-cTnI assay, to be used |

| |strategy? |in conjunction with risk stratification tools such as those examined here. Three of |

| | |these pathways (m-ADAPT, EDACS, and HEART) had very low associated negative |

| | |likelihood ratios without an overly high rule-in rate. Of these, only the HEART |

| | |score was assessed using acute coronary syndrome (rather than acute MI) as an |

| | |outcome. Given how well it performed it will likely be useful in conjunction with |

| | |hs-cTnI for patients presenting to our emergency department. |

|D. |Will patients be better off as a result of |Likely yes. In this study, just over half of patients were low risk by the HEART |

| |the test? |score pathway and would hence be able to be discharged from the ED without further |

| | |testing and with a very low risk of acute coronary syndrome in the subsequent 30 |

| | |days. The ability to discharge these patients after only 2-3 hours would potentially|

| | |help reduce length of stay, reduce ED overcrowding, and improve patient |

| | |satisfaction. It would be helpful to know how many patients presenting to our ED |

| | |with chest pain underwent serial (vs single) troponin testing prior to discharge to |

| | |gauge how this will affect our throughout. |

Limitations:

1. This study was a retrospective review of previously collected data, subject to issues of missing data and misinterpretation of subjective data. HEART score data in particular were not collected as part of the initial studies, and it is unclear how data points were scored given their potential subjectivity.

2. Subjects were recruited via convenience sampling with subsequent risk of selection bias.

3. The authors report sensitivity, specificity, and negative and positive predictive values for their results. This is particularly problematic given the low prevalence of acute MI and acute coronary syndrome in these cohorts. Likelihood ratios would have been more useful as they can be used with pre-test probability to determine the likelihood of disease in those with negative and positive results.

4. While these results suggest that these pathways are useful in ruling out disease in select patients (high negative predictive value, low likelihood ratios) the Vancouver Chest Pain and NOT rule pathways left a large number of patients in the "not low risk group" who would require further testing.

Bottom Line:

This retrospective review of previously enrolled cohorts found that 5 clinical decision rules, used in conjunction with 0 and 2 hour hs-cTnI measurements, resulted in sufficiently high negative predictive values (and low negative likelihood ratios) to allow early discharge of patients from the ED with low risk of acute MI or acute coronary syndrome.

-----------------------

PGY-3

Critical Review Form

Diagnostic Test

Greenslade JH, Carlton EW, Van Hise C, et al. Diagnostic Accuracy of a New High-Sensitivity Troponin I Assay and Five Accelerated Diagnostic Pathways for Ruling Out Acute Myocardial Infarction and Acute Coronary Syndrome. Ann Emerg Med. 2018;71(4):439-451.e3

................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download