False positive cardiac cath lab activations – PowerPoint

Here’s an interesting PowerPoint presentation that corresponds to a previous post.

I found slide 14 to be particularly interesting.

This is a topic that doesn’t get enough attention. Often the quarterly STEMI meetings go over the success stories but not the failures. It’s often said that if you don’t have any false positives you aren’t trying hard enough.

I don’t disagree, but they should be reported, and the ECGs should be analyzed for teaching points. Hindsight is 20/20 and I understand that, but very few 12-lead ECGs are more interesting than those that caused a false positive cardiac cath lab activation.

Find them, scan them, and post them! Can you think of a better educational tool than an archive of STEMI mimics that actually led to a patient being emergenty cathed?

Speaking of false positive cardiac cath lab activations, read these comments by Sameer Mehta, MD, FACC, MBA in the Cath Lab Digest.

He says in part:

I cautioned against complacency towards proceeding with emergent cath/percutaneous coronary intervention (PCI), citing precisely the high false alarms that have been mentioned in this outstanding study reported by Dr. David Larson. By the American College of Cardiology (ACC)/American Heart Association (AHA) criteria for primary stenting, the rates for these “false alarms” should be less than 15%. By this standard, the 14% of the false alarms cited by Dr. Larson at the Minneapolis Heart Institute Foundation at Abbott Northwestern Hospital is quite acceptable. Yet the authors have creditably deemed these rates as unacceptably high. The reader must also be made aware that the Minneapolis experience, with its Spoke and Wheel, pharmaco-invasive model of triage for primary PCI is one of the most advanced programs in the world, and one that has established superb guidelines and pathways for very effective triage for STEMI patients. I emphasize the excellent caliber of the work at Minneapolis Heart Institute since their high false alarm rates may actually be some of the lowest in the nation, and that the problems of these false alarms may be much higher at other institutions, in particular, at low-volume STEMI institutions…

There are several ways for individual institutions to get their arms around this burgeoning problem. It is obvious that the emergency department (ED) physicians are under great stress to diagnose STEMI — they have to be very accurate and very fast. It is a new responsibility that has been assigned to them quite rapidly…

[S]everal contributing authors as well as I have strongly emphasized the need to monitor the false alarm rates. We have declared these rates to be the best parameters of measuring the efficacy of a STEMI program…

[A]dministrations and medical staff must mandate high caliber for ED physicians that would participate in STEMI programs. Rigorous training in EKG interpretation is the cornerstone of this new role and continuous quality improvement (CQI) processes must be rigid in this assurance. To be perfectly candid, if any institution cannot provide such quality ED physicians, it has no business in declaring its ability to perform 24/7 STEMI interventions. In a situation where the high accuracy of the ED physician cannot be ensured, the institution must seriously consider to reverting to the time-tested method of the cardiologist evaluating the presenting EKG.

In STEMI Interventions: Managing the Chaos (found at theheart.org), Tim Henry, MD gives a different perspective:

[E]ven the issue of false-positives is of some debate. For instance, Dr. Dave Larson who works with me had a very nice paper in JAMA a year ago that looked at this. We found that 14% of our patients don’t have a clear culprit artery, but of those patients, there are about 40% who have positive enzymes. So there are other things that cause acute STEMI that are not necessarily related in need PCI. For instance, you can have spasm, you can have thrombus that resolves, and you can have stress cardiomyopathy. There are a variety of things that can do it. So if your patient has true ST-elevation and positive enzymes it’s hard to call that a false positive. So, I just think that what you do is a true false-positive rate, using it with ED and paramedic activating the cath lab is really between 6% to 8%, which we certainly think is acceptable.

It’s an interesting debate, and one I think we’re going to be hearing more about as D2B times below 90 minutes become commonplace in the wake of the D2B Alliance and AHA Mission: Lifeline.

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