Low High-Sensitivity Troponin Thresholds Identify Low-Risk Patients With Chest Pain Unlikely to Benefit From Further Risk Stratification

Risk Scores for Clinical Risk Stratification of Emergency Department Patients With Chest Pain but No Acute Myocardial Infarction: A Systematic Review

BACKGROUND

Chest pain is a common cause for emergency department (ED) presentations. After myocardial infarction (MI) has been ruled out by means of electrocardiography and troponin testing, decisions around anatomic or functional testing may be informed by clinical risk scores. We conducted a systematic review to synthesize evidence of the prognostic performance of chest pain risk scores among ED patients who have had MI ruled out by means of a high-sensitivity troponin assay.

METHODS

We queried multiple databases from inception to May 17, 2022. We included studies that quantified risk of 30-day major adverse cardiac events (MACE), at different cutoffs of clinical risk scores, among adult patients who had MI ruled out by means of a high-sensitivity troponin assay. Prognostic performance of each score was synthesized and described, but meta-analysis was not possible.

RESULTS

Six studies met inclusion criteria. Short-term MACE risk among patients who had MI ruled out by means of high-sensitivity cardiac troponin assays was very low. The HEART score, with a cutoff of 3 or less, predicted a very low risk of MACE among the greatest proportion of patients. Other scores had lower sensitivity or classified fewer patients as low risk.

CONCLUSIONS

The HEART score with a cutoff value of 3 or less accurately identified the greatest number of patients at low risk of 30-day MACE. However, MACE risk among patients who have MI ruled out by means of high-sensitivity troponin testing is sufficiently low that clinical risk stratification or noninvasive testing may be of little additional value in identifying patients with coronary disease.

External validation of a low HEAR score to identify emergency department chest pain patients at very low risk of major adverse cardiac events without troponin testing

BACKGROUND

The history, ECG, age, risk factor (HEAR) score has been proposed to identify patients at sufficiently low risk of acute coronary syndrome that they may not require troponin testing. The objective of this study was to externally validate a low HEAR score to identify emergency department (ED) patients with chest pain at very low risk of 30-day major adverse cardiac events (MACE).

METHODS

This was a secondary analysis of a prospective cohort of patients requiring troponin testing to rule out myocardial infarction (MI) in a large urban ED. HEAR scores were calculated in two cohorts: (1) patients with no known history of coronary artery disease (CAD); and (2) all eligible patients. The proportion of patients classified as very low risk, sensitivity, specificity, predictive values and likelihood ratios at each cut-off were quantified for index acute myocardial infarction (AMI) and 30-day MACE at HEAR = 0 and HEAR ≤ 1 thresholds.

RESULTS

Of the 1150 patients included in this study, 820 (71.3%) had no history of CAD, 97 (8.4%) had index AMI and 123 (10.7%) had 30-day MACE. In patients with no prior history of CAD, HEAR ≤ 1 identified 202 (24.6%) of patients as very low risk for 30-day MACE with 98.4% (95% CI 91.6-99.9%) sensitivity. Among all patients, HEAR ≤ 1 identified 202 (17.6%) patients as very low risk for 30-day MACE with 99.2% (95% CI 95.6-99.9%) sensitivity.

CONCLUSIONS

A HEAR score ≤ 1 can identify more than 17% of all patients as very low risk for index AMI and 30-day MACE and unlikely to benefit from troponin testing. Broad implementation of this strategy could lead to significant resource savings.

Diagnostic Performance of Novel Troponin Algorithms for the Rule-Out of Non-ST-Elevation Acute Coronary Syndrome

BACKGROUND

The European Society of Cardiology (ESC) rule-out algorithms use cutoffs optimized for exclusion of non-ST elevation myocardial infarction (NSTEMI). We investigated these and several novel algorithms for the rule-out of non-ST elevation acute coronary syndrome (NSTE-ACS) including less urgent coronary ischemia.

METHOD

A total of 1504 unselected patients with suspected NSTE-ACS were included and divided into a derivation cohort (n = 988) and validation cohort (n = 516). The primary endpoint was the diagnostic performance to rule-out NSTEMI and unstable angina pectoris during index hospitalization. The secondary endpoint was combined MI, all-cause mortality (within 30 days) and urgent (24 h) revascularization. The ESC algorithms for high-sensitivity cardiac troponin T (hs-cTnT) and I (hs-cTnI) were compared to different novel low-baseline (limit of detection), low-delta (based on the assay analytical and biological variation), and 0-1-h and 0-3-h algorithms.

RESULTS

The prevalence of NSTE-ACS was 24.8%, 60.0% had noncardiac chest pain, and 15.2% other diseases. The 0-1/0-3-h algorithms had superior clinical sensitivity for the primary endpoint compared to the ESC algorithm (validation cohort); hs-cTnT: 95% vs 63%, and hs-cTnI: 87% vs 64%, respectively. Regarding the secondary endpoint, the algorithms had similar clinical sensitivity (100% vs 94%-96%) but lower clinical specificity (41%-19%) compared to the ESC algorithms (77%-74%). The rule-out rates decreased by a factor of 2-4.

CONCLUSION

Low concentration/low-delta troponin algorithms improve the clinical sensitivity for a combined endpoint of NSTEMI and unstable angina pectoris, with the cost of a substantial reduction in total rule-out rate. There was no clear benefit compared to ESC for diagnosing high-risk events.

Prehospital troponin as a predictor of early clinical deterioration

BACKGROUND AND OBJECTIVES

Elevated troponin T (cTnT) values are associated with comorbidities and early mortality, in both cardiovascular and noncardiovascular diseases. The objective of this study is to evaluate the prognostic accuracy of the sole utilization of prehospital point-of-care cardiac troponin T to identify the risk of early in-hospital deterioration, including mortality within 28 days.

METHODS

We conducted a prospective, multicentric, controlled, ambulance-based, observational study in adults with acute diseases transferred with high priority by ambulance to emergency departments, between 1 January and 30 September 2020. Patients with hospital diagnosis of acute coronary syndrome were excluded. The discriminative power of the predictive cTnT was assessed through a discrimination model trained using a derivation cohort and evaluated by the area under the curve of the receiver operating characteristic on a validation cohort.

RESULTS

A total of 848 patients were included in our study. The median age was 68 years (25th-75th percentiles: 50-81 years), and 385 (45.4%) were women. The mortality rate within 28 days was 12.4% (156 cases). The predictive ability of cTnT to predict mortality presented an area under the curve of 0.903 (95% CI: 0.85-0.954; P < .001). Risk stratification was performed, resulting in three categories with the following optimal cTnT cut-off points: high risk greater than or equal to 100, intermediate risk 40-100 and low risk less than 40 ng/L. In the high-risk group, the mortality rate was 61.7%, and on the contrary, the low-risk group presented a mortality of 2.3%.

CONCLUSIONS

The implementation of a routine determination of cTnT on the ambulance in patients transferred with high priority to the emergency department can help to stratify the risk of these patients and to detect unknown early clinical deterioration.

Prospective comparative evaluation of the European Society of Cardiology (ESC) 1-hour and a 2-hour rapid diagnostic algorithm for myocardial infarction using high-sensitivity troponin-T

OBJECTIVE

Both 1- and 2-hour rapid diagnostic algorithms using high-sensitivity troponin (hs-cTn) have been validated to diagnose acute myocardial infarction (MI), leaving physicians uncertain which algorithm is preferable. The objective of this study was to prospectively evaluate the diagnostic performance of 1- and 2-hour algorithms in clinical practice in a Canadian emergency department (ED).

METHODS

ED patients with chest pain had high-sensitivity cardiac troponin-T (hs-cTnT) collected on presentation and 1- and 2-hours later at a single academic centre over a 2-year period. The primary outcome was index MI, and the secondary outcome was 30-day major adverse cardiac events (MACE). All outcomes were adjudicated.

RESULTS

We enrolled 608 patients undergoing serial hs-cTnT sampling. Of these, 350 had a valid 1-hour and 550 had a 2-hour hs-cTnT sample. Index MI and 30-day MACE prevalence was ~12% and 14%. Sensitivity of the 1- and 2-hour algorithms was similar for index MI 97.3% (95% CI: 85.8-99.9%) and 100% (95% CI: 91.6-100%) and 30-day MACE: 80.9% (95% CI: 66.7-90.9%) and 83.3% (95% CI: 73.2-90.8%), respectively. Both algorithms accurately identified about 10% of patients as high risk.

CONCLUSIONS

Both algorithms were able to classify almost two-thirds of patients as low risk, effectively ruling out MI and conferring a low risk of 30-day MACE for this group, while reliably identifying high-risk patients. While both algorithms had equivalent diagnostic performance, the 2-hour algorithm offers several practical advantages, which may make it preferable to implement. Broad implementation of similar algorithms across Canada can expedite patient disposition and lead to resource savings.

Comparing conventional and high sensitivity troponin T measurements in identifying adverse cardiac events in patients admitted to an Asian emergency department chest pain observation unit

Background

High sensitive cardiac troponin assays can be used for prediction of major adverse cardiac events (MACE) in patients with chest pain.

Methods

We included patients with symptoms suggestive of acute coronary syndrome in the emergency department observation unit. We compared the accuracy of conventional troponin T (cTnT) with high sensitive troponin T (hsTnT) at various ranges, as well as the utility of hsTnT and cTnT in prediction of 30-day and 1-year MACE.

Results

1023 patients were included (68.1% male, median age 56 years). There were 2712 hsTnT and cTnT values compared. hsTnT had a higher AUC than cTnT for 30-day and 1-year MACE. The optimal cut-off of 0-hour hsTnT for 30-day (PPV 34%, NPV 96.6%) and 1-year MACE (PPV 40.2%, NPV 94.2%) was 16 ng/L.

For 844 patients who had values for both 0 and 2 h hsTnT, we proposed a rule-out cut-off of 0 and 2 h hsTnT < 16 ng/L (NPV 97.0%, 95%CI 95.5–98.1%) and a rule-in cut-off of 0 and 2 h hsTnT ≥ 26 ng/L (PPV 58.8%, 95%CI 40.7%-75.4%) for 30-day MACE. Negative 0–2 h delta-hsTnT had poor predictive discriminant capabilities on 30-day (PPV 8.2%) and 1-year MACE (PPV 12.3%).

Conclusion

The cut off values of hsTnT used in the 0 and 2-hour algorithm to rule-out (16 ng/L) and rule-in MACE (26 ng/L) are in the range that previous cTnT assays are unable to measure accurately. Risk scores can be used to further improve NPV of the rule-out group. A fall in hsTnT level acutely is not predictive of MACE.