Normal electrical activation begins in the sinoatrial node and propagates through the atrium to the atrioventricular node and into the ventricle. Some patients with abnormal electrical activation require a pacemaker with leads implanted into the ventricle. This pacing changes the activation sequence to initially activate the ventricle in the region closest to the pacing electrode. Pacing also decreases mechanical function around the electrode and creates a gradient of regional stroke work (RSW) with the least work done near the pacing site and increasing with distance from the pacing location[1].