Arrhythmogenic potential in Turner syndrome patients

Introduction: Turner syndrome (TS) is associated with a range of distinct cardiovascular risks such as congenital heart disease and acquired cardiovascular disease. Data on arrhythmogenic potential in TS carriers are inconsistent, especially regarding the occurrence of malignant ventricular arrhythmias due to long QT interval. The aim of this study was to evaluate the prevalence of ECG abnormalities in patients with TS. Methods: 61 girls and women with TS syndrome were included in the study and underwent a cardiac examination including ECG and 24-hour ECG Holter monitoring. The 12-lead ECG was used to assess the length of PR and QT interval, the mean heart rate (HR) including z-score, presence of atrial/ventricular premature beats and other arrhythmias. QT interval was corrected according to Bazett and Hodges formulas, and both values were statistically compared. The relationship of parameters to individual karyotypes was analyzed. Results: Median PR interval was 120 ms (mean 118.4 ms), short PR interval was identified in 13% (8/61), none of the patients had delta wave as a manifestation of ventricular pre-excitation. Median of absolute QT values was 340 ms (mean 336 ms). QTc interval prolonged above 440 ms was observed in 5% (3/61) of patients using Bazett, and 3% (2/61) using Hodges formula. The QTc value according to Bazett significantly differed from the QTc according to Hodges (median 410 ms, mean 405 ms vs. median 390 ms, mean 390 ms; p <0.001). Regarding Holter monitoring, the median 24-hour HR was 92/min (mean 93.3/min). HR above +2 z-score was confirmed in 6.5% (4/61) of cases. Atrial and ventricular premature beats were detected in 48% (29/61) and 25% (15/61) of patients, respectively, with the highest frequency in monosomy 45.X. No clinically relevant arrhythmias were identified. Conclusions: ECG changes in TS individuals are as frequent as in the general population and are clinically insignificant. The increased risk of malignant arrhythmias was not demonstrated in this study. The Hodges formula seems to be more appropriate than the widely used Bazett formula for the evaluation of the QTc interval in TS patients.