# Electrocardiographic Fragmented Activity (II):
## 3 Materials and Methods
### Databases  
As mentioned above, in this work we used four different databases, namely, Strag-DB, SWfrag-DB, FHCM-DB and HCM-DB. Each of them includes both affected and control recordings in order to be able to apply and benchmark the selected learning techniques.  
The Strag-DB was created using control records (from healthy subjects) and modifying them by synthetic incorporation of fragmented waves. This added element was stemmed according to  
\[F(t)=A\cdot\sin\left(\frac{\pi nt}{w}\right) \tag{1}\]  
where \(A\) is a random number between 1% and 30% of the main peak amplitude, \(t\) is the time vector with its values going from 0 to \(2w\), \(w\) is a random number between 4 and 24 ms that represents the fragmentation duration and \(n\) represents the number of semi-cycles of the sinusoid. This database was extensively developed including this wide variety of possible values in the variables included in the equation to even overcome any imaginable composition of the fragmentation: (i) From almost invisible values of amplitude to exceeding possible ones; (ii) From low frequencies to very high ones; (iii) From just a section of the wavelength to a number of them. This sinusoid was applied to the first 150 ECG from 418 control ECG recorded from students of Universidad Catolica San Antonio (Murcia, Spain). These ECG were recorded using the ELI 350 from MortaraTM, a device that uses 500 Hz sampling frequency and 5 mV resolution. The demographic data from this ECG population were a men-to-woman ratio of 314/104 and \(23.1\pm 4.3\) years. The fragmented positive-to-negative ratio were 150/150. An example of a control (fragmented) record from this database can be seen in Figure 1a,b.  
The SWfrag-DB was created to simulate the effect of wide miss-conduction areas on the heart. Hence, we used the same previous control database, but this time synthetically fragmented using the following sinusoid equation,  
\[F(t)=A\cdot\sin(2\pi ft) \tag{2}\]  
where \(A\) is a random number between 1% and 30% of the main peak amplitude, \(t\) is the time vector and its values going from 0 to \(2w\), \(w\) is a random number between 20 ms and 40 ms that represents the fragmentation duration and \(f\) is a random number from 45 to 75 representing the frequency, in Hertz, of the sinusoid. An example of a record from this database can be seen in Figure 1c  
The FHCM-DB was created using 80 standard 12-lead ECG records from HCM positive diagnosed patients. For the development of this database, the presence of fragmentation was identified by two independent clinical reviewers, from Hospital Clinico Universitario Virgen de la Arrixaca (Murcia, Spain). This batch was selected inside a larger set of 225 cases. The demographic data of the whole database was 47.0 \(\pm\) 15.9 years and men-to-women ratio of 152/73. These ECG were recorded with GE-MAC 5000 from General ElectricTM at 500 Hz sampling rate and 4.88 mV resolution. The fragmented positive-to-negative ratio was 42/38. An example of a record from this database can be seen in Figure 1d.  
The HCM-DB comprised the fibrosis cases and it is a subset of 300 records from a larger database of 1750 cases of analyzed HCM patients including positively fibrosis diagnosed patients using MRI-LGE. These records were collected, analyzed and diagnosed by the expert clinicians in our group, from Hospital Clinico Universitario Virgen de la Arrixaca (Murcia, Spain). The signal-recorder was PageWriter TC30 from PhilipsTM at 500 Hz sampling rate and 5 mV resolution. The demographic data of the whole database were \(55.3\pm 16.4\) years and a men-to-women ratio of 651/1099. The fibrosis positive-to-negative ratio was 150/150. An example of a record from this database can be seen in Figure 1e.