ABSTRACT Atrial Fibrillation (AF) is characterized by a disorganized activation of the atrium leading to impaired cardiac function and more serious complications like embolic stroke, worsening heart failure, and increased mortality. AE affects 9% of the U.S. population (2% younger than 65) and contributes to 750,000 hospitalizations and 130,000 deaths per year. There is a clear unmet clinical need for a novel noninvasive imaging modality able to accurately diagnose, classify, and localize the origin of advanced arrythmias like AF with the goal of making better treatment decisions and improving patient outcomes. The objectives of this proposal are to develop, optimize, and validate the first transthoracic Acoustoelectric Cardiac Imaging (tACI) system for real-time, high resolution mapping of cardiac currents and arrythmias through the chest wall. This patented technology combines ultrasound with high frequency radiofrequency recording to remotely map electrical currents in the body (e.g., heart, brain) at high resolution. If successful, tACI will achieve noninvasive electrical mapping of the ventricles and atria at the mm and ms scales, thereby providing high diagnostic accuracy for classifying advanced arrythmias like AF, localizing its origins, guiding treatment decisions and reducing medical errors, leading to better outcomes for patients. The long-term goal at ElectroSonix is to commercialize and translate revolutionary and portable ACI technology to the clinic, doctor’s office, and point-of-care for improving diagnosis and treatment for all types of arrythmias. The global cardiac diagnostic and monitoring devices market is expected to surpass $10 billion by 2020, growing at 4.0% CAGR, while the specific market for noninvasive diagnostic imaging (e.g., ECG) is expected to reach $1 billion globally by 2025 at a CAGR of 2.0%. A clinical system based on tACI technology would impact this sector by greatly improving the accuracy for diagnosing and classifying arrythmias. Further, by localizing the origins of arrythmias, the proposed clinical tACI system would help guide treatment decisions, reduce medical errors, and improve quality of life for patients suffering from AF and other advanced arrythmias.