On March 16, 2016, the US Food and Drug Administration (FDA) convened a meeting of the Circulatory System Devices Panel to consider a premarket approval application for the AngelMed Guardian System based on the results of the pivotal ALERTS trial (AngelMed for Early Recognition and Treatment of STEMI) (URL: http://www.clinicaltrials.gov. Unique identifier: NCT00781118). The system comprises an implantable device similar to a single-chamber pacemaker, an external device that the patient carries, and a physician console. The device analyzes ST-segment shift through a single active-fixation lead in the right ventricular apex. If ST shift is identified, then the implantable device vibrates and the external device flashes and sounds an auditory alarm. More than 1 in 3 acute myocardial infarctions occur without chest pain, most commonly in women, diabetic patients, and the elderly. ST shift occurs rapidly in humans following coronary balloon occlusion.1 The AngelMed Guardian aims to reduce time to presentation by alerting the patient to ST shift even in the absence of symptoms. The ALERTS trial tested the safety and effectiveness of the Guardian System. A Bayesian adaptive design was used to adjust sample size based on interim treatment effect. The trial enrolled high-risk patients with a history of coronary artery disease (97% had previous revascularization). The trial was stopped early because of concerns that the predictive model did not accurately account for new Q waves. Nine hundred ten patients had the Guardian implanted (451 in the treatment arm versus 456 in the control arm with the device deactivated). Study …