False Positive Cardiac Cath Lab Activations

Here are some highlights from Larson, Menssen, Sharkey et al “False-Positive” Cardiac Catheterization Laboratory Activation Among Patients With Suspected ST-Segment Elevation Myocardial Infarction, JAMA 2007;298(23):2754-2760.

The false positive rates (suspected STEMI patients with ST-segment elevation but no clear culprit coronary artery, no significant coronary artery disease, and negative cardiac biomarker results) were analyzed at the Minneapolis Heart Institute at Abbott Northwestern Hospital in Minneapolis, Minnesota (a tertiary cardiovascular center with referral relationships with community hospitals throughout Minnesota and western Wisconsin).

First the authors note:

“Time to reperfusion is a major determinant of outcome in patients presenting with an ST-segment elevation myocardial infarction (STEMI). The American College of Cardiology/American Heart Association STEMI guidelines recommend that the emergency department physician make the decision regarding reperfusion therapy within 10 minutes of interpreting the initial diagnostic ECG, which may be challenging because clinical decisions are often made without a previous ECG result for comparison or time to observe evolutionary ST-segment changes or cardiac biomarker results…

Here’s the bombshell:

Of the 1335 patients who underwent angiography, 187 (14%) did not have a clear culprit coronary artery, 10 patients (0.7%) had multiple potential culprit arteries (severe 3-vessel disease and positive cardiac biomarker results), and 1138 (85.3%) had a clear culprit artery. Patients with a culprit artery were treated with percutaneous coronary intervention (94%), coronary artery bypass surgery (4%), or medical management (2%). Retrospective review of the index ECG indicated that 24 atients (1.8%) did not have diagnostic ST-segment elevation but instead had ST-segment depression, T-wave inversion, or nonspecific ST-T changes, including 3 patients with positive biomarker results (2 with non-STEMI and 1 with a drug overdose) and 21 with negative cardiac biomarker results. These patients were included in the no-culprit artery group. The prevalence of false-positive catheterization laboratory activation with the no-culprit coronary artery criteria was 14%…

The authors then pose a difficult question:

“Achieving door-to-balloon times in less than 90 minutes is an important quality metric that is tied to pay for performance and has been the focus of recent quality improvement initiatives such as the American College of Cardiologyís D2B Alliance and the American Heart Associationís Mission: Lifeline. Upstream activation of the cardiac catheterization laboratory by the emergency department physician is one of the key strategies to reducing door-to balloon times. A major challenge for the emergency department physician is the patient who presents with nonspecific symptoms or subtle ST-segment elevation or QRS repolarization abnormalities that obscure or mimic ST segment elevation. In these cases, is it best to immediately activate the catheterization laboratory, considering the consequences of a false alarm, or take the time to obtain additional data, such as from serial ECGs, biomarkers, or an echocardiogram?

One final note that I found interesting:

“Patients with new or presumably new left bundle-branch block had an inordinately high prevalence of false positive catheterization laboratory activation (almost half did not have a culprit artery). Patients with a previous myocardial infarction or previous coronary bypass surgery had a significantly higher prevalence of no culprit artery, likely because of abnormal baseline ECG results.”

It would be interesting to know whether or not the false positive LBBB patients met Sgarbossa’s criteria. The authors don’t say it, but I can’t help but wonder if the patients with previous MI “and abnormal baseline ECG results” had persistent ST segment elevation similar to (what we think of as) left ventricular aneurysm.

See also:

The problem of ST segment elevation

False positive cardiac cath lab activations – PowerPoint

1 Comment

  • Sonnet says:

    I remembered I was a specialist in a duty. When I activated the cath lab team just before infroming my consultant. Thanks God, It was true positive. Otherwise,…

1 Trackback

Leave a Reply

Your email address will not be published. Required fields are marked *

EMS 12-Lead

Cardiac Rhythm Analysis, 12-Lead ECG Interpretation, Resuscitation

JEMS Talk: Google Hangout

Comments
Proficiency vs Deficiency… The Art Of Electrocardiography | EMS 12 Lead
Understanding Amiodarone
[…] on the highlighted title for an Amiodarone breakdown,¬†UNDERSTANDING AMIODARONE¬† ¬†One tool I use in these cases of bradycardia, is SPo2 monitoring. Remember, with every systole […]
2015-05-22 16:59:43
Wayne
12 Lead ECG – Lead Placement Diagrams
I have been doing EKG's for the past thirty years. It use to be that you always lay the patient in the supine position but here lately I have been told that with the patient sitting up right will not change the EKG, is this so ?
2015-05-21 17:37:37
Ivan Rios
Understanding Atropine
Hi Tony, thank you for writing. It's always a bit of a gamble to give opinion in such topics without being there, however, addressing ventilation is a must. The rate could be secondary to vagal stimulation and/or respiratory depression, but it sounds like the patient is compensating pretty well when it comes to the hemodynamic…
2015-05-21 12:55:43
Tony Correia
Understanding Atropine
Looking for an opinion. Had a pt. who was unconscious from unknown etiology, Agonal respiration = 6, SPO2 = 59, heart rate =37 sinus bradycardia, B/P = 137/80 . We ventilate the pt. approx for 2 minutes without change in status. Would you have administered atropine or continue with BVM to attempt to correct hypoxia,…
2015-05-21 12:16:26
dan
57 year old male: Chest Discomfort
I'm sorry but I don't see any flutter here. With a rate of 150 we are at the very upper limit of sinus tach. No O2 is indicated with a pulse ox of 94%, especially if you are thinking cardiac. Place in position of comfort, large bore IV, fluid bolus, ASA, nitro, capnography, complete assessment…
2015-05-14 03:50:36

ECG Medical Training

12-Lead ECG Challenge Smartphone App

Photobucket

12-Lead ECG Challenge Smartphone App - $5.99

  • Apple iOS
  • Android
  • Amazon
  • Web Based

  • FRN-TV video review
  • iMedicalApps.com review
  • Interested in resuscitation?

    FireEMS Blogs eNewsletter

    Sign-up to receive our free monthly eNewsletter

    Visitor Map / Stats

    Locations of visitors to this page


    LATEST EMS NEWS

    HOT FORUM DISCUSSIONS