Treatment and Outcomes of Patients with Suspected Acute Coronary Syndromes in Relation to Initial Diagnostic Impressions (Insights from the Canadian Global Registry of Acute Coronary Events [GRACE] and Canadian Registry of Acute Coronary Events [CANRACE])
What is the predictive accuracy of the GRACE risk score among patients with “definite” versus “possible” acute coronary syndrome (ACS)?
This was a retrospective analysis of Canadian patients who had been enrolled in the GRACE/GRACE2 and CANRACE registries between 1999 and 2008. Demographic and clinical characteristics, use of cardiac procedures, prognostic accuracy of the GRACE risk score, and in-hospital outcomes between patients given an admission diagnosis of “definite” versus “possible” ACS by the treating physician were compared. Definite ACS was defined as having a recorded diagnosis of myocardial infarction (MI), whether STEMI, non–ST-segment elevation MI (NSTEMI), or unstable angina. Possible ACS was defined as a recorded working diagnosis of “rule out MI,” “chest pain,” or “other cardiac.”
Overall, 11,152 and 5,466 patients were given an initial diagnosis of “definite” ACS and “possible” ACS, respectively. Patients with “possible” ACS had a slightly higher GRACE risk score (median 130 vs. 125), greater rates of in-hospital MI (9.0% vs. 2.0%, p < 0.05), and heart failure (12% vs. 8.9%, p < 0.05). The GRACE risk score demonstrated excellent discrimination for in-hospital mortality in the overall study population.
The authors concluded that the GRACE risk score provides accurate risk assessment regardless of the initial diagnostic impression. Those patients with “possible” ACS had higher GRACE scores, and experienced significantly greater rates of MI, heart failure, or pulmonary edema.
While this analysis lends credibility to the use of the GRACE risk score regardless of the initial clinical impression (i.e., ‘definite’ vs. ‘possible’ ACS), it draws attention to the morbidity and mortality that may be experienced by patients with atypical presentations in whom an initial clinical assessment would suggest ‘possible’ ACS. Patients with ‘possible’ ACS had higher rates of adverse in-hospital outcomes (possibly because of delayed treatment and testing owing to the initial diagnostic impression). Probably as a consequence of the initial diagnostic impression, those with ‘possible’ ACS less frequently received evidence-based therapies or testing. The use of objective risk scores is paramount for the early and accurate identification of ACS and avoiding adverse outcomes.
Keywords: Pulmonary Edema, Myocardial Infarction, Acute Coronary Syndrome, Hospital Mortality, Chest Pain, Canada, Cardiovascular Diseases, Risk Assessment
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