Analysis of the P-wave
In all patients, the body-surface 12-lead ECG was recorded at a paper
speed of 25 mm/s with a calibration of 1 mV = 10 mm and analyzed
thoroughly for the calculation of the maximum P-wave amplitude, minimum
P-wave amplitude, maximum P-wave duration, minimum P-wave duration, and
PWD. For P-wave analysis, the most recent ECG recording of sinus rhythm
recorded just prior to CIED implantation was used (Figure 2). P-wave
duration and PWD were manually measured in all leads with an ECG
magnifier being used to mark the P-wave onset and offset, respectively.
The P-wave duration was defined as the time measured from the onset to
the end of the P-wave deflection. The onset of the P-wave was considered
to be the junction between the isoelectric line and the first visible
upward or downward slope of the trace, while the return of the trace to
its isoelectric line was considered to be the end of the P-wave. When a
P-wave exhibited a biphasic form, the latter negative phase was also
included in the P-wave duration (Figure 3A). The P-wave amplitude was
measured as the height of the peak of positive deflection or the depth
of the bottom of negative deflection from the isoelectrical line of the
onset point.14–17 In the case of a biphasic P-wave,
the P-wave amplitude was measured as the difference between the positive
peak and negative bottom of the recording (Figure 3A). For P-wave
analysis, durations and amplitudes of P-waves in leads II and V1 and the
maximum P-wave duration in all 12 leads were used as the parameters of
interest. Furthermore, PWD was calculated as the difference between the
maximum and minimum P-wave durations in milliseconds within the same
12-channel ECG (Figure 3B).8,18