Chest pain, RBBB but “STEMI Negative”: Is this a false cath lab activation, or a false cancellation?

A 90 year old with a history of atrial fibrillation presented with two weeks of intermittent retrosternal chest pain lasting minutes. An hour prior to presentation it became constant and more severe, accompanied by nausea and general weakness, and the paramedics brought them to the ED as a code STEMI. Heart rate was in the 50s and other vitals normal. What do you think?     There ’s atrial fibrillation, a right bundle branch block, normal axis and normal voltages. RBBB should produce secondary ST depression and T wave inversion in the anterior leads with the RsR’ (as it does in V1). But here in V2 there’s inappropriate ST elevation and upright T wave. There’s also mi ld STE in I/aVL, discordant to the slurred S wave, which cansometimes be seen in RBBB. But there are also down/up T waves in III/aVF which are reciprocal to what could be hyperacute T waves in I/aVL: compare the bulk of these T waves and their size relative to the QRS, compared with the normal sized T wave in V5-6. So this could be RBBB with the “South African flag” pattern of injury in I/aVL/V2 with reciprocal change in III/aVF, corresponding to occlusion of the first diagonal artery[1]. The same pattern was seen on the ECG the paramedics performed, which initiated their STEMI transfer: note the concordant ST elevation in V2 with strai ghtening of the ST segment.   Cardiology assessed the patient in the ED and noted: “RBBB with isolated 1.5mm STE concave...
Source: Dr. Smith's ECG Blog - Category: Cardiology Authors: Source Type: blogs