Drug-induced Cardiotoxicity -Jon Ford, MD The following is a response to an educational ECG series from the UC Davis EM Residency Program which is led by Dr. Bryn Mumma. The ECG showed a widened QRS with a prolonged QTc due to a multi-agent overdose. Dr. Ford, who I like to refer to as our toxicology program's Program Director Emeritus, provided this mental model for drug-induced cardiotoxicity. As you have pointed out, this is a complicated ECG. I will admit that when I looked at it, my eyes immediately went to the terminal R wave in aVR and the wide QRS and I thought classic sodium channel blocker. I admit that I do not have the expansive ECG knowledge base you do and I should have given it more thought. I am a basic person. When I teach about drug-induced cardiotoxicity, specifically drug-induced cardiac conduction problems, I like to break down the ECG into what each wave means in term of drug action and electropathophysiology. As you know, there are a few facts we can use to