Electrocardiography
Standard 12-lead ECG were recorded on a Marquette MAC 12 system
(Marquette Medical Systems, Inc. Milwaukee, WI) by trained technicians
during the participant’s examination. Computerized analysis of the ECG
data was performed using Minnesota and Nova code. PR prolongation on ECG
was defined as PR interval >200ms. The population was
divided into two groups based on the presence or absence of PR
prolongation. Then two groups were divided into four groups according to
the median of QRS axis in overall population. Among other parameters
considered in the analysis were P-wave duration, heart rate, P-wave
frontal axis, P-wave terminal force in V1 (PTFV1), QT interval and QRS
duration. The QT interval was corrected by Bazett’s formula.