Limited utility of exercise stress testing in the evaluation of suspected acute coronary syndrome in patients aged less than 40 years with intermediate risk features.

OBJECTIVE: National guidelines for management of intermediate risk patients with suspected acute coronary syndrome, in whom AMI has been excluded, advocate provocative testing to final risk stratify these patients into low risk (negative testing) or high risk (positive testing suggestive of unstable angina). Adults less than 40 years have a low pretest probability of acute coronary syndrome. The utility of exercise stress testing in young adults with chest pain suspected of acute coronary syndrome who have National Heart Foundation intermediate risk features was evaluated. METHODS: A retrospective analysis of exercise stress testing performed on patients less than 40 years was evaluated. Patients were enrolled on a chest pain pathway and had negative serial ECGs and cardiac biomarkers before exercise stress testing to rule-out acute coronary syndrome. Chart review was completed on patients with positive stress tests. RESULTS: The 3987 patients with suspected intermediate risk acute coronary syndrome underwent exercise stress testing. One thousand and twenty-seven (25.8%) were aged less than 40 years (age 33.3 ± 4.8 years). Four of these 1027 patients had a positive exercise stress test (0.4% incidence of positive exercise stress testing). Of those, three patients had subsequent non-invasive functional testing that yielded a negative result. One patient declined further investigations. Assuming this was a true positive exercise stress test, the incidence of true positive exercise stress testing would have been 0.097% (95% confidence interval: 0.079-0.115%) (one of 1027 patients). CONCLUSIONS: Routine exercise stress testing has limited value in the risk stratification of adults less than 40 years with suspected intermediate risk of acute coronary syndrome.

Introduction of an accelerated diagnostic protocol in the assessment of emergency department patients with possible acute coronary syndrome: the Nambour Short Low-Intermediate Chest pain project.

Emergency physicians can feel pressured by opposing forces of clinical reality and the need to publish successful key performance indicators in an environment of increasing demands and cost containment. This is particularly relevant to management of patients with undifferentiated chest pain and possible acute coronary syndrome. Unreliability of clinical assessment and high risk of adverse outcomes for all concerned exist, yet national guidelines are at odds with efforts to reduce ED crowding and access block. We report findings from the Nambour Short Low-Intermediate Chest pain risk trial, which safely introduced an accelerated diagnostic protocol with reduced ED length of stay and high patient acceptability. Over a 7-month period, there were no major adverse cardiac events by 30 days in 19% of undifferentiated chest pain presentations with possible acute coronary syndrome discharged after normal sensitive cardiac troponin taken 2 h after presentation and scheduled to return for outpatient exercise stress test.

Comparison of three risk stratification rules for predicting patients with acute coronary syndrome presenting to an Australian emergency department.

OBJECTIVES: To compare the predictive ability of three risk stratification tools used to assess patients presenting to the ED with potential acute coronary syndrome. DESIGN: Pre-planned analysis of an observational study. SETTING: A single tertiary referral hospital. PARTICIPANTS: 1495 patients presented with chest pain. 948 patients were screened and enrolled. Patients with at least 5 min of chest pain suggestive of ACS were eligible. INTERVENTIONS: Subjects were risk categorised using the Heart Foundation of Australia/Cardiac Society of Australia and New Zealand guidelines (HFA/CSANZ), the TIMI score and the GRACE score. Three strata of the TIMI and GRACE score were used to compare to the HFA/CSANZ risk categories. MAIN OUTCOME MEASUREMENT: 30-Day cardiac event rates including cardiac death, acute myocardial infarction and unstable angina. RESULTS: There were 152 events in 91 patients (9.6%). The discriminatory ability of the scores determined by the AUC was 0.83 (95% CI 0.79-0.87) for the GRACE score, 0.79 (95% CI 0.74-0.83) for TIMI score and 0.75 (95% CI 0.70-0.80) for HFA/CSANZ. The AUCs with three strata of the GRACE and TIMI scores were 0.76 (95% CI 0.72-0.81) and 0.68 (95% CI 0.62-0.73) respectively. CONCLUSIONS: All three scores were similar in performance in quantifying risk in ED patients with possible ACS. The GRACE score identified a sizable low risk cohort with high sensitivity and NPV but complexity of this tool may limit its utility. Improved scores are needed to allow early identification of low- and high-risk patients to support improvements in patient flow and ED overcrowding.