Sending to the cath lab? Ensure accurate ECG interpretation first

GE HealthCare

As healthcare centers bolster their efforts to reduce door-to-balloon times among STEMI patients, many facilities are now reckoning with the flip side of that coin: that is, the more providers send cases to the cath lab, the higher the risk of false activations—patients getting sent to catheterization who don't really have STEMI.

One study in JRSM Cardiovascular Disease puts that risk into a before/after context, noting that inappropriate activations of the STEMI cath lab occurred in less than 10% of cath lab cases before 2013, the year when the American Heart Association and American College of Cardiology issued guidelines that recommended activating the cath lab within 10 minutes of the first ECG.1 In the years since those recommendations, the false activation rate has jumped up to 15 to 40%.

Many of these false activations—some as high as 72%—are linked to Emergency Department (ED) physicians and other clinicians misreading initial ECGs and interpreting waveforms as indicating STEMI when they actually do not. For instance, a study published in Journal of Multidisciplinary Healthcare found that the majority of Emergency Medical Technicians (EMTs) couldn't distinguish between STEMI and STEMI mimics.2 Often, it's only after the STEMI cath lab activation that a cardiologist reviews the ECG to determine whether to call off reperfusion.

These risks notwithstanding, ECG is still critical to diagnostic decision-making, particularly within the "golden hour" of STEMI interventions. However, the impact of false activation on financial costs and quality of care emphasizes the importance of ensuring accurate ECG interpretation from the start.

Implications of inappropriate cardiac catheterization activation

When a false activation occurs, the cancellation most often takes place before patients have a chance to undergo catheterization. Still, patients may experience a range of lasting repercussions from that initial wrong diagnosis.

Importantly, every minute spent pursuing a STEMI misdiagnosis is a minute lost from treating the underlying concern correctly. As the authors in JRSM Cardiovascular Disease emphasize, sometimes those underlying concerns may be quite serious, even if they are not myocardial infarction. For example, many critical conditions can cause ST elevations, including intracerebral hemorrhage, aortic dissection, and pulmonary thromboembolism. If interventions such as administration of anticoagulants are made based on a false STEMI assumption, it could deteriorate care even further.

Though obviously not as dire as the risk of delayed interventions for life-threatening conditions, there are also cost considerations tied to false cath lab activation. In one estimate from a study in Cardiovascular Diagnosis & Therapy examining the financial burden of after-hours cancellations, authors quantified a $350 cost for activations that were canceled before catheterization took place.3 If catheterization was done, that burden more than doubled to $865—and would no doubt come with greater risks to patients undergoing a major procedure that wasn't needed.

A study in the Journal of American Heart Association notes that false cath lab activation can also contribute to staff burnout and lead to a loss of urgency over time.4


Ensuring an accurate diagnosis

The 2023 European Society of Cardiology recommends that patients should still be referred to the catheterization lab immediately following a working diagnosis of STEMI.5 However, given the risks of false activations, providers should be cautiously aware of the variants that can conflate diagnoses.

Aside from more critical conditions, such as a pulmonary embolism, the JRSM Cardiovascular Disease paper lists many others that can contribute to ST elevations and increase the likelihood of STEMI misdiagnoses. These include electrolyte abnormalities, acute pericarditis, and even natural manifestations in some patient populations. As a paper published in the Journal of Electrocardiology adds, left hypertrophic cardiomyopathy is another contributor to ST elevation that can be misdiagnosed as STEMI.6

Clinicians must understand which ECG patterns do and do not indicate STEMI, and they should also factor in medical history, gender, symptoms like angina, and other chart details in their diagnoses, even if they must make those determinations quickly. Fortunately, emergent technology such as artificial intelligence for ECG interpretation could help physicians connect multiple data points to accelerate diagnostic decisions.

ECG remains a vital tool for making immediate point-of-care decisions regarding suspected STEMI patients, but as with any tool, users must operate from the correct manual for the best outcomes. Everyone who participates in ECG interpretation (even ED physicians and EMTs) should understand the nuances of sending patients to the cath lab, including what signs warrant activation. STEMI or not, every minute matters, so make the most of each one.


1. Degheim G, Berry A, and Zughaib M. False activation of the cardiac catheterization laboratory: The price to pay for shorter treatment delay. JRSM Cardiovascular Disease. 2019;8:2048004019836365.

2. Alrumayh AA, Mubarak AM, Almazrua AA, et al. Paramedic Ability in Interpreting Electrocardiogram with ST-segment Elevation Myocardial Infarction (STEMI) in Saudi Arabia. Journal of Multidisciplinary Healthcare. 2022;15:1657-1665.

3. Shamim S, McCrary J, Wayne L, et al. Electrocardiograhic findings resulting in inappropriate cardiac catheterization laboratory activation for ST-segment elevation myocardial infarction. Cardiovascular Diagnosis & Therapy. 2014;4(3):215-223.

4. Kontos M, Gunderson M, Zeegre-Hemsey J K, et al. Prehospital Activation of Hospital Resources (PreAct) ST‐Segment–Elevation Myocardial Infarction (STEMI): A Standardized Approach to Prehospital Activation and Direct to the Catheterization Laboratory for STEMI Recommendations From the American Heart Association's Mission: Lifeline Program. Journal of the American Heart Association. 2020;9(2):e011963.

5. Byrne R A, Rossello X, Coughlan J J, et al. 2023 ESC Guidelines for the management of acute coronary syndromes: Developed by the task force on the management of acute coronary syndromes of the European Society of Cardiology (ESC). European Heart Journal. 2023;44(38):3720-3826,

6. Yang Y, Pei Y, Situ Q, et al. ECG criteria to distinguish hypertrophic cardiomyopathy featured with "Pseudo-STEMI" from acute ST-elevation myocardial infarction. Journal Of Electrocardiology. 2023;77:10-16.