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Three Part Question

In [adult patients presenting to the emergency department with suspected ST-segment elevation myocardial infarction], what is the [prevalence] of [false-positive cardiac catheterization laboratory activation]?

Clinical Scenario

A 68-year-old female presents to your emergency department with chest pain and dyspnea. Her ECG reveals sinus tachycardia and slight ST elevation in leads I and aVF with reciprocal ST depression in leads I and aVL. Before activating the cardiac catheterization laboratory, you consider the other causes of ST-segment elevation.

Search Strategy

Medline 1946-05/14 using OVID interface, EMBASE, and PubMed clinical queries
[(exp myocardial infarction/diagnosis) AND (exp cardiac catheterization) AND (false positive.mp)]. Limit to English language.

Search Outcome

18 papers were identified; four were relevant to the clinical question.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Larson Dec 2007 USA	1335 patients undergoing cardiac angiography after activation by emergency physicians for suspected STEMI	Prospective cohort	Prevalence of false-positive catheterization laboratory activation in patients with suspected STEMI in 3 Groups: 1.Patients with ST-elevation, but no clear culprit lesion, 2. STEMI, no significant CAD, 3. STEMI, negative cardiac biomarker	1138 had clear culprit artery. 10 had multiple potential culprit arteries. Group 1:187 had no culprit artery with 60 mod-severe CAD (16 positive biomarkers, 44 negative biomarkers). Group 2: 127 no significant CAD (48 positive biomarkers, 79 negative biomarkers) with etiologies including myocarditis (15, 31%), stress cardiomyopathy (15, 31%), and STEMI by cardiac MRI (14, 29%). Group 3: Negative cardiac biomarkers. 149 had negative biomarkers. 26 had clear culprit artery. Women had higher prevalence of no culprit artery (17.1%) as well as no significant CAD (13.6%). Patient with left bundle-branch block (36): no culprit artery (16, 44%), no significant CAD (10, 27%), negative biomarkers (13, 36%)	Categorized by discharge diagnosis (may have been presumed or suspected) Does not address missed STEMI
McCabe JM, Armstrong EJ, Kulkarni A, et al Jun 2012 USA	At two centers, 411 patients referred to coronary angiography by emergency physicians for STEMI	Prospective cohort	False positive STEMI included any patient who underwent catheterization who lacked thrombotic total or subtotal occlusion. Patients in whom angiography was not performed and did not have 2/3 of the following: Positive cardiac biomarkers, ECG findings consistent with STEMI, Alternative diagnosis	411 ED STEMI diagnosis. 352 had angiography: 101 (29%) had no culprit lesion, 39 (9.5%) had no stenosis >20%, 59 patients did not have angiography, 45(75%) false-positive STEMIs. Of the false-positive: Less frequently white or Asian, Had lower BMI, Atypical symptoms/less arrest/less hypotension, Diagnosed during standard hours, More illicit drugs, Known or reported history of CAD, Lower amplitude EKG elevations	Broad definition of false-positive STEMI. Urban population.
Nfor T, Kostopoulos L, Hashim H, et al. Oct 2012 USA	489 patients diagnosed with STEMI by emergency physicians receiving emergency cardiac catheterization	Prospective Cohort	Absence of clear culprit lesion on coronary angiography	489 patients coronary angiography: 54 (11%) had no culprit lesion. Predictors of false-positive STEMI: absence of chest pain, no reciprocal ST-segment changes, fewer than 3 cardiovascular risk factors, symptom duration longer than 6h	Small sample size Single study site Validation of risk score
Kontos MC, Kurz MC, Roberts CS May 2010 USA	249 emergency physician activations of the cardiac catheterization laboratory for suspected STEMI	Case Series	4 Groups: 1. ECG diagnostic for STEMI and diagnosed with MI, 2. Initial EKG met ST-segment elevation for STEMI but MI was excluded, 3. Patients with concerning EKG but did not meet criteria for STEMI, 4. After activation of cath lab and cardiology evaluation findings were not thought to be STEMI or ischemia	Group 1: 188 (76%) were true STEMI, 13 did not have angiography performed. Group 2: 37 (15%) did not have myocardial necrosis but underwent catheterization, 11 had significant disease with 6 having PCI 26 had no significant disease. Group 3: 11 patients. 9 had angiography and 4 had significant disease. Group 4: 13, (5.2%) unnecessary activation	Categorized by discharge diagnosis (may have been presumed or suspected) Does not address missed STEMI

Comment(s)

Prompt evaluation of patients with suspected ST-segment elevation myocardial infarction is necessary to achieve the recommended door-to-balloon time of <90 minutes. Because of this, routine clinical assessment and laboratory data are often bypassed and patients are sent to emergency cardiac catheterization when revascularization is not indicated. Data from the above mentioned studies show that there are a significant number of patients who undergo cardiac catheterization without significant disease or culprit artery. False ST-segment elevation MI were more often found in patients with absence of chest pain, no reciprocal ST-segment changes, fewer than 3 cardiac risk factors, symptom duration >6h, women, history of illicit drug abuse, history of known CAD, lower amplitude EKG elevations, and new LBBB. Further studies are needed in larger patient samples to further characterize predictors of false-positive STEMI.

Editor Comment

RB

Clinical Bottom Line

A significant portion of STEMI activations is considered false-positive activations. More studies are needed to further characterize patients who are likely to have false-positive STEMI activations

References

1. Larson DM, Menssen KM, Sharkey SW, et al False-Positive Cardiac Catheterization Laboratory Activation Among Patients With Suspected ST-Segment Elevation Myocardial Infarction JAMA 2007 Dec 19;298(23):2754-60
2. McCabe JM, Armstrong EJ, Kulkarni A, et al Prevalence and factors associated with false-positive ST-segment elevation myocardial infarction diagnoses at primary percutaneous coronary intervention–capable centers: a report from the Activate-S Arch Intern Med. 2012 Jun 11;172(11):864-71
3. Nfor T, Kostopoulos L, Hashim H, et al. Identifying false-positive ST-elevation myocardial infarction in emergency department patients. J Emerg Med. 2012 Oct;43(4):561-7
4. Kontos MC, Kurz MC, Roberts CS An evaluation of the accuracy of emergency physician activation of the cardiac catheterization laboratory for patients with suspected ST-segment elevation myocardial infarction Ann Emerg Med 2010 May;55(5):423-30