2.3.3. ECG Features

The key focus for simple AF detection are three diagnostic ECG features, representative of the ventricular rate (RR-interval: RRi), AV synchronization time (PQ-interval: PQi), and P-/f-wave amplitude (PQ-amplitude: PQa), statistically evaluated as mean values and standard deviations (std) over the total available ECG record length (5-144s). The list of computed features is as follows:

We note that if a P-/f-peak is not detected before a Q-wave, then the respective measurements are not included in the statistical computations of PQi-mean, PQi-std, PQa-mean, and PQa-std.

The computation of four lead-specific features (PQi-mean, PQi-std, PQa-mean, and PQa-std) for each of the 12 ECG leads gives the opportunity to apply the concept of varying dimensions in electrocardiography. According to this concept, AF rhythm diagnosis could be made possible according to the lead availability in an arbitrary clinical setting, e.g., one-lead (using any of 12 leads by means of 6 features: 2RRi + 2(PQi = PQa)), six-lead (using limb or chest leads by means of 26 features: 2RRi + 6 × 2(PQi + PQa)), or twelve-lead (using all 12 leads by means of 50 features: 2RRi + 12 × 2(PQi + PQa)).