Clinical Challenge: A patient presents to Genius General Hospital status post cardiac arrest with the following EKG. What do you think is going on? What would your next management steps be?
Answer: The cause of the ST elevation here is Osborne waves due to hypothermia. The patient was packed in ice prior to a long inter-hospital transfer (an antiquated, dangerous practice). Upon arrival, his core temperature was 29C (84F).
Based upon the circumstances of the arrest and this EKG, the ICU team suspected that the patient did not have coronary disease. To confirm these suspicions, they reviewed his original EKG from the outside hospital. Before being packed in ice when his core temperature was higher, his EKG was nearly normal. This supports that the new ST changes are due to hypothermia rather than ischemia.
Post-arrest EKGs are notoriously confusing to interpret, because patients are highly dynamic and suffer from numerous conditions that can affect the cardiogram, for example:
- Type I MI (ischemia due to plaque rupture)
- Type II MI (ischemia due to the intense stress of cardiac arrest)
- Takotsubo cardiomyopathy a.k.a. stress cardiomyopathy (again, due to the stress of arrest)
- Electrolyte shifts
- Temperature changes
The key to interpreting these EKGs is often to see how they evolve over time (with resuscitation, management of electrolyte abnormalities, rewarming, etc.). This case was a bit unusual in that the cause of the EKG abnormality was an iatrogenic complication of excessive cooling – so this could be sorted out immediately by reviewing a prior EKG.
…some feedback from twitter:
Great case. This is a case we had during my PICU rotation years ago. ~15 year old M sudden collapse during track and field. ROSC in the field. Therapeutic hypothermia overshot to 29C. https://t.co/RG2sc7TboJ pic.twitter.com/tvD4jpzmxt
— Nick Sawyer, MD, MBA, FACEP (@NickSawyerMD) October 4, 2020
We just published this in Resuscitation Plus: “Do not disregard initial 12 lead ECG after out-of-hospital cardiac arrest: It predicts angiographic culprit despite metabolic abnormalities. 1st EKG after ROSC as good as 2nd for diagnosing OMI. Both were about 72% accurate for OMI.
https://www.sciencedirect.com/science/article/pii/S2666520420300321 (full text)
I agree that when the first ECG shows diffuse ST depression of subendocardial ischemia with STE in aVR that it will usually resolve with time. However, if the ECG shows occlusion, the first is just as accurate as the second in spite of metabolic abnormalities.
Abstract:
Objectives: The initial 12 lead electrocardiogram (ECG) following return of spontaneous circulation (ROSC) after out-of-hospital cardiac arrest (OHCA), is often disregarded by clinicians in ability to predict acute thrombotic coronary occlusion (ATCO) due to markedly abnormal metabolic milieu (AMM). We sought to evaluate the accuracy of initial vs. follow-up ECG prior to invasive coronary angiography (ICA) to predict ATCO following resuscitated OHCA.
Methods: We included OHCA patients with initial shockable rhythm who underwent invasive coronary angiography (ICA). AMM was defined as one of: pH 2 mmol/L, serum potassium 6.0 mEq/L. Two ECGs A (initial) and B (follow-up) following ROSC but prior to ICA were adjudicated by 2 experienced readers using expanded ECG criteria to predict angiographic ATCO on ICA.
Results: 152 consecutive patients (mean age 58 years, 75% male) met inclusion criteria, 77% had AMM. Among those with both ECGs (n ¼ 102), overall accuracy, sensitivity, specificity, positive predictive value, negative predictive value for correctly predicting angiographic ATCO for ECG A was 72%, 63%, 81%, 61%, 83% and for ECG B was 71%, 50%, 91%, 73%, 80% respectively. Predictive accuracy for angiographic ATCO was similar between ECG A [odds ratio (OR) 7.31, CI 2.87–18.62, p < 0.0001) and ECG B [OR 10.67; CI 3.6–31.61, p < 0.0001], and consistent in AMM.
Conclusions: In OHCA, despite AMM, the initial post ROSC ECG retains a statistically significant, and similar accuracy as the follow-up ECG to predict angiographic ATCO using expanded criteria.
Thanks Steve!! That will help understand these post-arrest EKGs, which can be incredibly confusing.