Coronary Artery Disease
Usefulness of the Troponin-Ejection Fraction Product to Differentiate Stress Cardiomyopathy from ST-Segment Elevation Myocardial Infarction

https://doi.org/10.1016/j.amjcard.2013.10.013Get rights and content

The presentation of stress cardiomyopathy (SC) with nonobstructive coronary artery disease mimics that of ST-segment elevation myocardial infarction (STEMI) due to coronary occlusion. No single parameter has been successful in differentiating the 2 entities. We thus sought to develop a noninvasive clinical tool to discriminate between these 2 conditions. We retrospectively reviewed 59 consecutive cases of SC at our institution from July 2005 through June 2011 and compared those with 60 consecutives cases of angiographically confirmed STEMI treated with primary percutaneous coronary intervention in the same period. All patients underwent acute echocardiography, and the peak troponin I level was determined. The troponin-ejection fraction product (TEFP) was derived by multiplying the peak troponin I level and the echocardiographically derived left ventricular ejection fraction. Comparing the SC and STEMI groups, the mean left ventricular ejection fraction at the time of presentation was 30 ± 9% versus 44 ± 11%, respectively (p <0.001), and the peak troponin I was 7.6 ± 18 versus 102.2 ± 110.3 ng/dl, respectively (p <0.001). The mean TEFP was thus 182 ± 380 and 4,088 ± 4,244 for the SC and STEMI groups, respectively (p <0.001). Receiver operating characteristic curve analysis showed that a TEFP value ≥250 had a sensitivity of 95%, a specificity of 87%, a negative predictive value of 94%, a positive predictive value of 88%, and an overall accuracy of 91% to differentiate a true STEMI from SC (C-statistic 0.91 ± 0.02, p <0.001). In conclusion, for patients not undergoing emergent angiography, the TEFP may be used with high accuracy to differentiate SC with nonobstructive coronary artery disease from true STEMI due to coronary occlusion.

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Methods

After obtaining approval from the institutional review board, we retrospectively reviewed 76 consecutive cases at our institution (from July 2006 through June 2012) with acute coronary syndromes, in whom coronary angiography demonstrated nonobstructive coronary disease and in whom a diagnosis SC was made. We also reviewed 80 consecutives cases of angiographically confirmed STEMI due to coronary occlusion during the same period, starting in July 2006. The demographic data, medical history,

Results

We initially evaluated 76 cases of presumed SC; of which, 17 were excluded because of not meeting inclusion criteria or for the presence of at least 1 exclusion criterion. Therefore, we analyzed 59 consecutive cases of definite SC. In the STEMI group, 80 consecutive cases were initially reviewed, but 20 did not satisfy the inclusion and/or exclusion criteria and were excluded from the analysis (Figure 1). The final study population thus consisted of 59 patients with SC and 60 patients with true

Discussion

The principal contribution of our study is the development of the troponin × LVEF product (TEFP), as a simple clinical tool to accurately distinguish SC from STEMI. TEFP ≥250 had 88% positive predictive value to predict STEMI, with 95% negative predictive value when <250. This readily available index thus may enhance the likelihood of accurately discriminating these 2 conditions in critically ill patients with other serious co-morbidities, in whom immediate cardiac catheterization is not

Disclosures

Dr. Stone is a consultant for Boston Scientific, Minnesota.

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