The Sneaky Circumflex Coronary Artery

The Story Trumps the ECG and Sometimes Even the Troponin

ECG #1

ECG #2

These electrocardiograms (ECGs) are from a 33-year-old man with a history of gastroesophageal reflux who presented to the emergency department (ED) late in the afternoon during my recent two weeks as the cardiology consult attending.

The patient complained of atypical chest discomfort which was made worse by leaning forward, and relieved by lying down. His initial high sensitivity cardiac troponin T (cTnT) was elevated to 74 ng/L (normal less than 23). His ECG #1 (above) was normal so we requested repeat ECGs and cTnTs. His repeat ECG #2 several hours after the first showed tall R waves in leads V2 and his repeat cTnT had increased to 258. We recommended emergent cardiac catheterization which demonstrated total occlusion of the left circumflex coronary artery (LCX), which was treated with angioplasty and a stent.

This case demonstrates several of the 500 Rules of Cardiology, some discussed previously.

- Always repeat the ECG in patients with chest discomfort. I learned this when I was a resident in the ED at Tufts. I was about to discharge a former Tufts Chief Medical Resident with atypical chest pain from the ED because his ECG was normal, when I thought, “This guy is no dummy, maybe he knows something I don’t.” I decided to repeat the ECG 20-30 minutes after the first and, to my horror, the ECG showed an acute inferior wall myocardial infarction. There was nothing we did for such patients at that time (1974) except admit them to the coronary care unit, keep them in the hospital for three weeks (!), and resuscitate them if they arrested, but it would have been quite embarrassing if I let him go home.

- Tight CCX lesions hide because their electrical effects may not be seen because electricity does not conduct well through tissue and, therefore, decreases rapidly with distance from the source, which for CCX lesions is the posterior wall. So don’t ignore a good story for ischemia just because the ECG is normal even during discomfort or with exercise. A good story trumps the ECG.

- The anterior lead ECG changes produced by CCX ischemia or infarction are the reverse of the changes produced by anterior wall ischemia or infarction. So a tall R wave in the anterior leads is the posterior wall’s q wave. See – https://pauldthompsonmd.substack.com/p/dont-miss-posterior-wall-mis

- cTN blood levels are lower, and may even be normal early on, in patients with a totally occluded coronary artery because no one has “flushed the toilet.” If you’re a sanitation worker at the sanitation plant, you don’t see any XXXX if the sewer line is blocked or if no one flushed the toilet. A good story can even trump the cTn. See the post from March 21, 2024 entitled “Make Sure the Patient Flushed the Toilet”.

#acutemyocardialinfarction #cardiology #heartattack #circumflex #coronaryarteries