Cardiac Science is a global medical device company and a subsidiary of Opto Circuits Ltd. They focus exclusively on noninvasive ways to manage heart disease.

Cardiac Science is the inventor of the modern stress test, the single-channel interpretive electrocardiograph (ECG/EKG), and the first fully automatic bedside defibrillator. Today, they design equipment to connect to hospital information systems (HIS) to electronic medical record systems (EMR) so caregivers can focus on patients, not administration and paper.