Validated risk stratification model accurately predicts low risk in patients with unstable angina

How useful are the Heart Foundation risk criteria for assessment of emergency department patients with chest pain?

OBJECTIVE

To investigate the prognostic utility of Heart Foundation (Australia) risk stratification table in an ED chest pain population.

METHODS

A planned sub-study of a prospective observational study of adult patients with potentially cardiac chest pain who underwent evaluation for acute coronary syndrome (ACS) was conducted. Data collected included demographical, clinical, ECG, biomarker and outcome data. Outcome of interest was diagnostic utility of the classification system for ACS or myocardial infarction (MI) at index presentation and major adverse cardiac events (MACE) within 7 and 30 days. MACE included death, cardiac arrest, revascularization, cardiogenic shock, arrhythmia and prevalent (cause of presentation) and incident (occurring within the follow-up period) MI. Analysis was by descriptive and receiver-operator curve analyses.

RESULTS

Seven hundred and sixty-eight patients were studied; 109 had MI (14.2%, 95% confidence interval [CI] 11.9-16.8%). There were 88 MACE at 7 days (13.5%, 95% CI 11.1-16.4%) and 93 MACE at 30 days (14.4%%, 95% CI 11.9-17.3%). Diagnostic performance (c-statistic) of the National Heart Foundation risk classification for ACS, MI, 7 and 30 day MACE was 0.74 for each (95% CI 0.71-0.77). Although sensitivity of the high-risk classification for MI, 7 and 30 day MACE was high (99-100%), specificity was low (48-50%).

CONCLUSION

The Heart Foundation risk classification shows only fair predictive performance for MI, 7 and 30 day MACE. With specificity of approximately 50%, the recommendation for coronary care admission for all high-risk patients is hard to justify.

The Incremental Value of Troponin Biomarkers in Risk Stratification of Acute Coronary Syndromes: Is the Relationship Multiplicative?

Structured Abstract

Clinical risk scoring beyond initial troponin values: results from a large, prospective, unselected acute chest pain population

BACKGROUND

Risk stratifying the diverse group of patients who present to hospital with chest discomfort remains challenging. Current clinical risk models, typically derived from selected populations, are limited by their relative complexity and the absence of a well-defined role of troponin.

OBJECTIVE

To derive a simple clinical risk score from a large, unselected population of patients with chest discomfort and to delineate the prognostic value of an initial troponin measurement.

METHODS

Prospective, consecutive data were collected from patients who presented to a tertiary care hospital. Multivariate analysis was used to identify variables predictive of the primary end point: death, nonfatal myocardial infarction or revascularization at 30 days. Integer values were assigned, generating a risk score to quantify individual patient risk.

RESULTS

Among 1054 patients, predictor variables included ST-segment deviation (strongest predictor -- assigned two points), male sex, prior congestive heart failure, three or more cardiac risk factors and prior acetylsalicylic acid use (one point each). There was a progressive increase in events with increasing total score (P<0.0001), with a 15-fold gradient from scores of 0 to 4 and greater. Although a negative troponin measurement was associated with fewer events for all scores, patients with higher scores remained exposed to substantial risk. A negative initial troponin measurement conferred a negative predictive value of 97.3% (95% CI 93.7% to 99.1%) among patients with a risk score of 0.

CONCLUSION

Significant 30-day events occurred in patients with elevated risk scores, despite negative initial troponin measurements, emphasizing the importance of clinical risk stratification. This simple clinical risk score, in conjunction with a single troponin I measurement, facilitates triage of patients who present to hospital with chest discomfort.

Clinical features in the emergency department can identify patients with suspected acute coronary syndromes who are safe for care in unmonitored hospital beds

BACKGROUND

Standard practice for patients requiring hospital admission with suspected acute coronary syndromes (ACS) is admission to a monitored cardiology bed. The Western Hospital Chest Pain Protocol was developed to identify a subset of these patients who could be safely managed in an unmonitored bed.

AIM

The objective of this prospective study of chest pain patients classified as 'high' or 'intermediate' risk by the Agency for Health Care Policy and Research/National Health and Medical Research Council guidelines was to further evaluate the safety of this protocol.

METHODS

This study was a prospective, observational, cohort study investigating the outcomes of patients admitted to hospital with suspected ACS. The primary outcome of interest was death or life-threatening arrhythmia within 24 h of hospital admission.

RESULTS

If the Western Hospital Chest Pain Protocol had been strictly applied, there would have been one death in the group assigned to unmonitored beds (1/750; 0.13%, 95% confidence interval 0.01-0.85%) and no other life-threatening arrhythmias.

CONCLUSION

There is a subgroup of patients with suspected ACS who require hospital admission who can, based on clinical and biochemical features in the emergency department, be safely assigned to unmonitored beds.

Impact of contemporary guideline compliance on risk stratification models for acute coronary syndromes in The Registry of Acute Coronary Syndromes

We compared the predictive value of the Rush score with the Thrombolysis In Myocardial Infarction (TIMI) risk score in unselected patients with an acute coronary syndrome and evaluated the effect of compliance with established guidelines on the accuracy of these models. The Registry of Acute Coronary Syndromes is a retrospective registry of 3,754 consecutive patients (38% women; mean age 67 years) who presented with acute coronary syndrome to the emergency department between April 1, 1999, and December 31, 2000, at 9 hospitals. The primary end point was death, myocardial infarction, or urgent revascularization during hospitalization. Rush classification was based on quartiles of predicted risk of cardiac complication (<2% for class I vs >15% for class IV). The TIMI score was implemented as published. Compliance with guidelines for acute coronary syndrome was assessed with a 4-point scale based on the aggregate use of aspirin, beta blockers, heparin, and glycoprotein IIb/IIIa inhibitors. Fifteen percent of patients met the primary end point. The primary end point rates for TIMI scores 0/1, 2, 3, 4, 5, and 6/7 were 11%, 14%, 13%, 11%, 14%, and 12%, respectively (p = NS). The primary end point rates for Rush classes I, II, III, and IV were 6%, 8%, 9%, and 17%, respectively (p <0.001). After controlling for compliance with established guidelines, the odds ratio of an event increased by 46% for each unit increase in Rush score (p <0.001). After adjusting for the Rush score, the odds ratio decreased by 54% for each unit increase in compliance (p <0.001). Thus, compliance with current American College of Cardiology/American Heart Association guidelines significantly improves prognosis, regardless of the risk score. The use of established risk scores may overestimate event rates in unselected populations.

Sources of diagnostic inaccuracy of conventional versus new diagnostic criteria for myocardial infarction in an unselected UK population with suspected cardiac chest pain, and investigation of independent prognostic variables

OBJECTIVE

To assess the degree and sources of current diagnostic inaccuracy of serial conventional cardiac markers and ECGs compared with the new diagnostic criteria for myocardial infarction, with specific reference to physician specialty and the prognostic value of troponin T.

DESIGN

Prospective, blinded observational study.

SETTING

University hospital.

PATIENTS AND INTERVENTIONS

All suspected cardiac chest pain admissions for six months, with additional blinded measurement of CK-MB mass and troponin T. World Health Organization and new criteria myocardial infarction diagnoses were made by an expert panel.

MAIN OUTCOME MEASURES

Diagnostic adjustment by expert panel; completeness of serial measurements; six months prognosis.

RESULTS

A complete set of serial cardiac markers was not taken in 38.7% of patients, this being twice as likely when managed by non-cardiologists than by cardiologists (p < 0.0001). The WHO myocardial infarction diagnosis was adjusted by the expert panel in 4% of cases, this being 90% more likely in patients admitted under non-cardiologists (p = 0.026). The new criteria for myocardial infarction identified an additional 27.3% of infarcts, with a diagnostic alteration in 12.0% of the cohort; 45.2% of these cases had a potentially preventable cause for diagnostic adjustment. Only troponin T (p = 0.0004), ST depression (p = 0.003), and heart failure (p = 0.016) were independently predictive of prognosis.

CONCLUSIONS

Chest pain patients appear less likely to be fully and accurately assessed by non-cardiologists than by cardiologists. The new criteria for myocardial infarction identify approximately 25% of additional patients as MI, with potential additional advantages related to simplicity of diagnostic protocols. Troponin T was the most potent predictor of six month prognosis in an unselected cohort of chest pain admissions.

Triage of patients with chest pain in the emergency department: a comparative study of physicians' decisions

PURPOSE

Little is known about physicians' triage decisions for patients with chest pain in the emergency department. We sought to understand better the variability and accuracy of physicians' triage decisions.

SUBJECTS AND METHODS

We used 20 simulated cases to compare triage decisions by 147 physicians (46 emergency medicine, 87 internal medicine, and 14 cardiology physicians) with triage decisions recommended by a previously validated prediction rule. We calculated triage sensitivity and specificity using the prediction rule to estimate the likelihood that each of the simulated patients would suffer a major complication. Triage sensitivity was defined as the proportion of all patients expected to have major complications who were triaged to the coronary care or inpatient telemetry unit.

RESULTS

Triage specificity was defined as the proportion of all patients without complications who were triaged to sites other than the coronary care or inpatient telemetry unit.Physicians' triage decisions were less sensitive (85% vs. 96%, P <0.001) and less specific (38% vs. 41%, P = 0.02) than decisions recommended by the prediction rule. Physicians overestimated patients' risk of complications and triaged more patients to inpatient monitored beds. Despite their preference for inpatient monitored beds, physicians' decisions would have resulted in four times as many major complications in patients who were not triaged to inpatient monitored beds, compared with decisions recommended by the prediction rule (2.4% vs. 0.6%, P <0.001). Although physicians' decisions were best explained by their provisional diagnoses, interphysician agreement about triage decisions (kappa = 0.34) and diagnosis (kappa = 0.31) was only fair.

CONCLUSIONS

In simulated cases, physicians' triage decisions varied widely and their predictions of patient outcomes differed markedly from that of the validated prediction rule, suggesting that use of the prediction rule in the emergency department could improve physicians' decisions and patients' outcomes.

[Is troponin I useful for predicting in-hospital risk for unstable angina patients in a community hospital? Results of a prospective study]

INTRODUCTION AND OBJECTIVES

Before including troponin I detection in the daily practice of our hospital we performed a prospective study to determine its real usefulness and to establish the best cut-off point.

METHODS

We studied 82 consecutive patients admitted with unstable angina to a community hospital. Troponin I was determined (> 10 h after chest pain). Patients were referred to a tertiary hospital for catheterization/revascularization if clinical events developed.

RESULTS

Twenty-five patients (31%) suffered events during admission: recurrent angina in 23 cases (28%); heart failure in 5 (6%); exitus in 3 (4%); myocardial infarction in 1 (1%). The cut-off point for troponin I that best predicted events was 0.1 ng/ml. Patients with troponin I > 0.1 (34 patients, 42%) experienced more events [47 vs. 19%; OR = 3.8 (1.4-10.4); p = 0.01] and had higher rates of recurrent angina (42 vs. 19%), heart failure (12 vs. 2%) and exitus (9 vs 0%). Patients with ECG changes and troponin I > 0.1 showed a significantly higher percentage of events (63%) than those with ECG changes alone (23%) or troponin I > 0.1 alone (15%) or those without ECG changes and troponin I < 0.1 (17%) (p < 0.0001).

CONCLUSIONS

Troponin I elevation is useful for predicting in-hospital risk for unstable angina patients admitted to a community hospital. A low cut-off value (0.1 ng/ml) predicts events. The association of ECG changes and high troponin I identifies a population at very high risk; however, the absence of both variables in patients with a diagnosis of unstable angina does not preclude the development of events.

Risk stratification in non-ST segment elevation acute coronary syndromes with special focus on recent guidelines

Patients with unstable angina or non-ST segment elevation (non-Q-wave) myocardial infarction are a heterogeneous group with respect to their risk of developing clinically significant adverse events such as subsequent myocardial infarction and death. Recent guidelines promote risk stratification of these patients, targeting high-risk patients for maximal antithrombotic and antiischemic therapy and low-risk patients for early discharge. We reviewed current and future modalities for risk stratification of patients and the predictive value of these methods in context with available pharmacologic agents. Unfortunately, most of the data identifying a particular pharmacologic regimen as beneficial in high-risk patients are retrospectively derived from large trials. Until prospective studies that use markers to guide therapy are available, clinicians should be familiar with the use of these risk markers and their application to the role of a given management strategy, including pharmacologic therapy.

Guidelines for the acute coronary syndromes

Traditional measures employed in the immediate management of patients presenting with an acute coronary syndrome have markedly reduced the risk of early death or myocardial infarction. Further incremental benefit is seen with the substitution of enoxaparin for unfractionated heparin, and in the use of glycoprotein IIb/IIIa inhibitors during percutaneous coronary intervention. However, the evidence for benefit from the glycoprotwin IIb/IIIa inhibitors with medical management alone is unconvincing. Newer data also suggest an aggressive approach to the high-risk patient offers a better ultimate outcome than a conservative one.

The contemporary management of acute myocardial infarction

The contemporary management of acute myocardial infarction continues to evolve rapidly. The ultimate goal of therapy is timely, complete, and sustained myocardial reperfusion. There is a powerful time-dependent effect on mortality, and thus the balance between the time and likelihood of maximal reperfusion is crucial in deciding whether to use primary percutaneous balloon angioplasty or thrombolysis as the initial reperfusion strategy. Newer thrombolytic agents allow for equivalent coronary reperfusion compared with the standard accelerated alteplase (tPA) regimen with the advantage of easier dosing regimens. Low molecular weight heparin has been shown to be superior to unfractionated heparin and likely will be the standard of care in the near future. The use of glycoprotein IIb/IIIa inhibitors has been shown to decrease the short- and long-term complication rates in patients with acute coronary syndromes treated medically and with percutaneous coronary interventions; however, the choice of the optimal agent and dosing regimen in various clinical settings remains controversial. Combination therapy with low-dose fibrinolytics, glycoprotein IIb/IIIa inhibitors, and low molecular weight heparin, with or without subsequent early planned percutaneous coronary interventions, may provide the optimal strategy for maximal coronary reperfusion, but the results of large, randomized mortality trials currently underway need to be analyzed. Risk stratification will continue to play a major role in determining which patients should receive a specific therapy. The care of the patient with an acute myocardial infarction will continue to be a challenge requiring the proper selection from the vast pharmaceutic and interventional options available.