You are seeing a 72yM with palpitations for 3 days. He has no other medical conditions and is otherwise well with no chest pain, no shortness of breath, no diaphoresis and no nausea. Heart rate is 140-150 and BP 131/77. Physical exam is otherwise normal. Your ECG shows an irregularly irregular rhythm at a rate of 146 with 0.5 mm ST depressions in concordant leads. You diagnose atrial fibrillation. After rate control with diltiazem the ST depressions resolve. Which of the following is TRUE?

About the Author: Anton Helman

Dr. Anton Helman is an Emergency Physician at North York General in Toronto. He is an Assistant Professor at the University of Toronto, Division of Emergency Medicine and the Education Innovation Lead at the Schwartz-Reisman Emergency Medicine Instititute. He is the founder, editor-in-chief and host of Emergency Medicine Cases.