Original Contribution
Rest myocardial perfusion imaging: a valuable tool in ED

https://doi.org/10.1016/j.ajem.2013.09.004Get rights and content

Abstract

Background

Acute chest pain is a frequent cause of emergency department (ED) visits. Rest myocardial perfusion imaging (RMPI) during or immediately after an episode of chest pain can provide diagnostic and prognostic information concerning acute coronary syndromes.

Aim

Our purpose was to evaluate the RMPI score in risk stratification of chest pain suspected to be of cardiac ischemic origin and negative troponin assessment.

Methods

Ninety-six patients without an ongoing myocardial infarction or a history of coronary artery disease and in whom RMPI was performed in the ED because of chest pain suspected to be related with acute myocardial ischemia were included.

Follow-up was performed considering the occurrence of death, myocardial infarction, or revascularization in a 12-month period admission.

Results

Fourteen (14.6%) patients had events. According to survival analysis, the variables related with events were a history of angina (hazard ratio [HR], 4.5; P ≤ .01), an ischemic electrocardiogram (HR, 4.0; P ≤ .01), the abnormal RMPI (HR, 11.4; P ≤ .05), and the RMPI score (HR, 1.1; P ≤ .0001). When the variables of interest were forced into a multivariate model, the χ2 associated with the model that includes clinical and electrocardiogram information was 16.3 (P ≤ .005) and in the model that also includes RMPI score, it was 23.0 (P ≤ .0005).

Conclusion

In a low- to intermediate-risk group of patients with suspected acute myocardial ischemia, RMPI gives not only diagnostic information but adds prognostic value to the traditional ED risk stratification tools.

Section snippets

Background

Suspicion of an acute coronary syndrome (ACS) in patients with chest pain is a frequent cause of emergency department (ED) visits. One of the most difficult challenges is to determine whether chest pain is cardiac related and if the patient is at increased risk for a cardiac event [1], [2], [3]. High-risk patients can be identified based on clinical history, electrocardiogram (ECG) changes, and cardiac enzyme elevation [3], [4]. A larger group of patients presenting, often, with a less urgent

Population

The hospital where this study was performed is a 1500-bed academic-based care hospital with approximately 140 000 ED visits per year. There is no dedicated chest pain unit. Percutaneous coronary intervention is available 24 h/d and, since 2002, it is possible to perform RMPI whenever is required by the ED department. Three hundred studies were performed until January of 2011. The patients enrolled in this study were included retrospectively based on their ED medical records, from January 1,

Results

Ninety-six patients with ongoing chest pain or a recent episode of chest pain suspected to be of cardiac origin and negative troponin (cTnI) assessment were included in this study. Table 1 summarizes the baseline characteristics of the population, including age, sex, type of pain, and presence of risk factors and of a previous history of angina relating these features with the occurrence of events. The mean age of the patients was 61.3 ± 12.7 years, 69.8% were men, and 21.9% had typical chest

Discussion

In the ED, the evaluation of patients with acute chest pain is a challenge and the physician is always balancing between the risk of an unnecessary admission and the risk of a premature discharge of a high-risk patient [2], [6], [7], [17], [18], [19], [20], [21].

The enrolled patients in this study were mainly middle-aged men (69.8%) complaining of atypical or noncardiac chest pain (78.1%), referring at least 1 risk factor for CAD (82.3%). There were no significant differences between the group

Clinical implications

Risk stratification of patients with chest pain is a difficult task, and the tools routinely used in the ED are not always sufficient, if our goal is a prompt and safe decision.

In this study, a relationship was found between the extension of perfusion defects in RMPI and the occurrence of cardiac ischemic events. The number of abnormal examinations was a concern. A follow-up study was, by this reason, essential. A normal perfusion was associated with lower event rate.

Rest myocardial perfusion

Limitations

This was an observational cohort single-center study with the limitations inherent to this kind of analysis. Coronary angiography was not performed in all of the included patients to assess the presence of CAD. To overcome this limitation, besides myocardial infarction and death, revascularization was considered an end point in patient follow-up.

Wall motion analysis, using gated acquisition, or attenuation correction was not performed, and this could contribute for a larger number of positive

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