Gender-related Ventricular Repolarization Differences in Healty Subjects. Comparative Study between Magnetocardiography and ECG

Previous ECG studies have shown gender-related differences of normal ventricular repolarization (VR) parameters. Aim of this study was to evaluate VR of healthy volunteers (HV) with unshielded magnetocardiographic mapping (MCG), in comparison with 12-lead ECG. Methods: 58 HV, 32 males (M), age 37.3±12.9 and 26 females (F), age 33±9.9, with normal ECG, were investigated at rest. A 36-channel system (sensitivity: 20 fT/Hz½) was used to record the MCG from the anterior chest wall. To assess VR, heart rate corrected (HRc) QTend, JTpeak, JTend and Tpeak-Tend intervals, were measured from both ECG and MCG. Moreover ST-integral and Tpeak magnetic field (MF) orientation (α), ST-dynamics and ST-stability were also calculated with MCG. To evaluate age-dependence of all parameters, pts were also divided in two age groups (> and < 35 years). Results: In F, both ECG and MCG HRc QTend, JTpeak, JTend were significantly longer than in M (p<0.002), with average ECG values 25 ms longer than MCG ones. Tpeak-Tend did not differ significantly. MCG ST angle was normal in all but 3 subjects and T angle in all, without significant differences between M and F. MCG ST-dynamics and ST-stability parameters were longer in F than in M (p<0.05). All parameters did not vary significantly between the two age groups. Conclusion: This study confirms that ECG parameters of VR are normally longer in healthy F as compared to M. Moreover it provides the first demonstration that similar differences can be measured with MCG, although absolute values are shorter in MCG. Other MCG parameters, such as MF-orientation, ST-dynamics and ST-stability, provide additional discrimination between M and F.