References
Pre-hospital risk stratification using a modified thrombolysis in myocardial infarction score: a retrospective medical record review
Abstract
Introduction:
Paramedics commonly convey patients with non-ST elevation acute coronary syndrome (NSTEACS) to emergency departments (EDs) where a risk stratification model (RSM) determines the risk of death or adverse cardiovascular events, and thus whether the patient should be transferred to a specialist heart attack centre (HAC) for an invasive procedure. If paramedics were to risk-stratify the patients in the pre-hospital environment using a modified thrombolysis in myocardial infarction (MTIMI) RSM, this could result in primary triage to an appropriate hospital.
Methods:
A retrospective medical record review was completed using patients from a metropolitan ambulance service, one ED and one HAC comparing the current method of identifying high risk NSTEACS with a new method; the MTIMI RSM. Positive predictive value, negative predictive value, logistic regression and receiver operating statistic area under the curve (c-statistic) were used to compare methods.
Results:
Notes of 108 patients were used in this study. Current practice produced a c-statistic (c) of 0.73 (95% CI 0.62 to 0.85) and the MTIMI RSM (c=0.72, CI 0.61 to 0.83). The best RSM overall was the abbreviated MTIMI RSM with only three variables identified through logistic regression (c=0.79, 0.68 to 0.89).
Conclusions:
Both methods of identifying high-risk NSTEACS were similar as they both used the ECG variable, which was approximately twelve times more prognostic than any other variable. The need to identify a pre-hospital RSM with a good prognostic power still exists; therefore, other RSMs should be explored in a prospective study.
In 2013/14 there were 80,724 hospital admissions in England and Wales for myocardial infarctions (Myocardial Ischaemia National Audit Project [MINAP], 2014). Despite being three times more prevalent than ST elevation myocardial infarction (STEMI) and having a higher long-term risk, non-ST elevation acute coronary syndromes (NSTEACS) have not been given as much consideration (Montalescot et al, 2007; Rothman and De Palma, 2009; MINAP, 2014). NSTEACS need risk-stratifying to determine which treatment modality is the most appropriate. Patients whose predicted six-month mortality is greater than 3% when risk-stratified by hospital clinicians using a validated risk-stratification model (RSM) are considered intermediate or high-risk for future adverse cardiovascular events (NICE, 2014). They require an angiogram, with revascularisation if required within 72 hours, or sooner if clinically unstable (NICE, 2014). The low-risk NSTEACS require non-invasive therapies, therefore they can be suitably managed in a hospital without percutaneous coronary intervention (PCI) facilities, but should still have cardiology input (MINAP, 2014).
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