Human ECGs
Twenty-four-hour Holter recordings (2/3-lead configuration, sampling rate: 200 Hz) were obtained from the Telemetric and Holter ECG Warehouse (THEW, hosted at the University of Rochester Medical Center, NY, USA), an initiative hosting a warehouse of digital Holter ECGs open to the scientific community (Couderc 2012). The E-HOL-03-0202-003 database of 200 healthy subjects (age>15: 39±16, 100 females and 100 males) was analysed. Healthy subjects were considered as eligible for enrollment and defined as healthy based on a battery of tests and information including no history of cardiovascular disease or disorders (stroke, TIA, peripheral vascular disease), no hasty of high BP (>150/90 mmHg), no medication, no chronic illness, normal physical examination, normal echocardiography, normal exercise testing and no pregnancy. The E-HOL-03-0480-013 database of genotyped LQTS patients was analysed for comparison with healthy subjects. Holter recordings were analysed from 104 untreated LQT1 patients (age > 15: 38±15, 60 females and 54 males) and 35 untreated LQT2 patients (age > 15: 37±15, 16 females and 19 males).