Treatment of cardiovascular disease inside medical facilities has improved dramatically in recent years. However, treatment of acute cardiovascular disease before patients arrive at those facilities has not kept pace. In order to fill this gap, we have developed a novel ECG system—“Mobile Cloud-based ECG (MCECG)”—that appears a clinically valid approach to this problem. MCECG is a cloud-computing system with wireless-transmission ECG units, whose clinical usefulness is due to the cloud-based server, allowing cardiovascular specialists inside medical facilities to give outside emergency caregivers diagnosis and treatment guidance. Ongoing studies include practical use of MCECG in the clinical setting of emergency care. We are collaborating with Kitasato University, Oita University, and Hokuto hospital. Clinical studies demonstrated the effectiveness of MCECG in improved prognostic outcome of patients with cardiovascular disease. And, based on these research results, the system has been put to practical use. NTT DOCOMO provides the system commercially.