2.2. Baseline characteristics and ECG data collection
Baseline characteristics included age, gender, body mass index, brain natriuretic peptide level, echocardiographic data, New York heart association class, patterns of ECG, and symptoms and medications. ECG recorded with paper speed = 25 mm/s and calibration = 10 mm/mV. GE Muse ECG data management system (GE Healthcare, Chicago, IL) was used to measure 12-lead ECG parameters. QRS complex parameters were measured using amplitude-based methods.