Brno University of Technology ECG Quality Database (BUT QDB)

BUT QDB is a database created by the cardiology team at the Department of
Biomedical Engineering, Brno University of Technology, for the purpose of
evaluating ECG quality. The data comprises 18 long-term recordings of single-
lead ECGs and associated 3-axis accelerometer data, collected from 15 subjects
(9 female, 6 male) aged between 21 to 83 years. Recordings were carried out
between August 2018 and October 2019 while the subjects were undertaking
ordinary everyday activities ("free-living conditions"). Data was collected
using a mobile ECG and accelerometer (Bittium Faros 180) with a sampling
frequency of 1,000 Hz for ECG signals and 100 Hz for accelerometer signals.
The minimum length of recording is 24 hours.

Three signals were fully annotated in terms of ECG signal quality. The
remaining 15 signals were annotated in two selected segments, each of 20
minutes in duration. Furthermore, five additional segments of poor signal
quality were also annotated. Signal quality was classified as follows: Class 1
indicates that all ECG significant waveforms (P wave, T wave and QRS complex)
are clearly visible and their onsets and offsets can be detected reliably;
Class 2 indicates that the noise level is increased and ECG significant points
cannot be reliably detected, but the signal enables reliable QRS detection;
Class 3 indicates that QRS complexes cannot be detected reliably and the
signal is unsuitable for any further analysis.