CODE: an annotated 12-lead ECG dataset containing exams from more than a million patients
Dataset with annotated 12-lead ECG records. The exams were taken in 811 counties in the state of Minas Gerais/Brazil by the Telehealth Network of Minas Gerais (TNMG) between 2010 and 2016. And organized by the CODE (Clinical outcomes in digital electrocardiography) group. - (available for research upon request).

CODE-test: an 12-lead ECG dataset annotated by multiple experts
Annotated 12 lead ECG dataset. Contain 827 ECG tracings from different patients, annotated by several cardiologists, residents and medical students. - (openly available).

CODE-15%: a large scale annotated dataset of 12-lead ECGs
A dataset of 12-lead ECGs with annotations. The dataset contains 345 779 exams from 233 770 patients. It was obtained through stratified sampling from the CODE dataset ( 15% of the patients). The data was collected by the Telehealth Network of Minas Gerais in the period between 2010 and 2016. - (openly available).

SaMi-Trop: 12-lead ECG traces with age and mortality annotations
SaMi-Trop is an NIH-funded prospective cohort of 1959 patients with chronic Chagas cardiomyopathy to evaluate whether a clinical prediction rule based on ECG, brain natriuretic peptide (BNP) levels, and other biomarkers can be useful in clinical practice. A subset of the SaMi-Trop dataset with annotations of age and mortality and the correspondent ECG traces is openly available here. - (openly available).