A patient in his 60s had been suffering from intermittent chest pain for three weeks, and the hospitalist wanted to send him home if his second troponin was negative, as I wrote about last month. (REM. 2022;44:28; http://bit.ly/BradyCardiaEMN.)
He had another episode of pain, however, while resting in the ER about three hours after arriving, and a new ECG was ordered.
His vital signs were normal, as was his physical exam at first, but eventually he started to look a bit pale and diaphoretic. The computer read the first repeat ECG as a normal sinus rhythm at 83 bpm (Fig. 1.), and a second repeat ECG was read the same way. (Fig. 2.)
Is the computer missing something in these ECGs?
I did not see any significant difference on the ECG taken 11 minutes after the onset of his pain nor on the one taken 35 minutes later, at least at first. I was actively involved at that time trying to bring cardiology to the patient’s bedside, and I had the tech repeat the ECG every 15 minutes because his chest pain was refractory to nitroglycerin and he was a high-risk patient.
I finally took a closer look after the patient came to the cath lab, and noticed that the T waves had reversed to aVL, often the first sign of inferior STEMI, and the ST segments were changing from concave to straight in the anterior leads. .
I asked Stephen W. Smith, MD, author of Dr. Smith’s ECG Blog (http://bit.ly/DrSmithsECGBlog), and he said the 11-minute repeat ECG had a vertical T wave in lead III, where he had previously shown a biphasic T. This indicates pseudonormalization, which is when a reperfused coronary artery had an abnormal T wave at rest reocclusion. The lower Wellens T wave straightens and appears normal when this reocclusion occurs, which is why it is called pseudonormal.
This seems normal, but it is not in the context of the clinical situation and the previous ECG. ECG taken at 35 minutes showed further progression of this plus new T wave inversion in the aVL. Dynamic changes in lead III ECG with return of symptoms, although subtle, confirmed the ECG reading taken on arrival which showed biphasic T waves in lead III while the patient was painless.
A high sensitivity troponin I was 14 ng/L on arrival and 10 ng/L when collected three or four hours later during the pain episode at rest (99% URL
An intra-aortic balloon pump and temporary pacemaker were placed and cardiothoracic surgery was consulted for emergency coronary artery bypass grafting.
It is important to do serial ECGs every 30 minutes for the first 90 to 120 minutes of an episode of chest pain that you suspect could be cardiac if the pain persists. Do them more frequently if you are particularly concerned about the patient. Keep in mind that a T wave inversion in the aVL is often the first sign of an inferior occlusion myocardial infarction. And do a second story before doing a second troponin to make sure you’re not dealing with unstable angina.
Dr Pregersonis an emergency physician at Palomar and Tri-City Medical Centers in San Diego. He is the author of 1-Minute Emergency Medicine Consultation, 8-in-1 Quick Reference for Emergency Services, A-Z Emergency Pharmacopoeia and Antibiotics Guide, and Think twice: no more lessons from urgency. Follow him on Twitter@EM1MinuteGuru, and visit its siteshttps://www.erpocketbooks.com/andhttps://em1minuteconsult.com. Read his past columns onhttp://bit.ly/BradyCardiaEMN.