ESPE Abstracts

Introduction: Turner syndrome (TS) is a genetic condition which is reported to be associated with electrocardiogram (ECG) abnormalities, of which the rate-corrected QT interval (QTc) is the most common indicated deviation. Our objectives were to gain more insight in the prevalence of QTc-prolongation using both Bazett's and Hodge's correction formulas in patients with TS of all ages and to investigate whether QTc prolongation is more prevalent in patients with a monosomy 45,X compared to patients with other karyotypes.

Methods: Girls and women with TS visiting the outpatient clinics of our tertiary medical centre were included in this study. Data on age, length, weight, karyotype, systolic and diastolic blood pressure, hypertension, cardiac malformations and comorbidities were obtained from the medical records. Karyotype (determined in blood and buccal mucosa (only in 45,X)) was divided into two groups: monosomy 45,X and other karyotypes. QT intervals of computerized and printed 12-leaded ECGs were measured manually by two researchers. A QTc interval of >450 ms for girls and >460 ms for women was considered prolonged. Prevalence of QTc prolongation was compared to the general population.

Results: In total 125 girls (age 1-18 years) and 225 women (age 19-65 years) were included. Monosomy 45,X was present in 33% of the patients. The mean QTc interval using Bazett's formula was longer compared to Hodge's formula (420 ± 25 ms versus 400 ± 20 ms, P<0.001). In total, 5% of the population had a prolonged QTc interval using the Bazett's formula (4% in girls and 6% in women) and 0% using Hodge's formula (1% in girls and 0% in women), which is in line with the prevalence reported in the normal population. Girls with TS had a higher basic heart rate, regardless of cardiac comorbidity, and a lower QTc interval compared to women with TS, regardless of the correction formula. Furthermore, patients with a monosomy 45,X karyotype had a higher basic heart rate compared to the patients with other karyotypes. Yet, the QTc interval was not significantly longer in patients with monosomy 45,X compared to patients with other karyotypes, when using both formulas.

Conclusion: This study shows that the QTc interval in patients with TS is not prolonged compared to the normal population using both Bazett's and Hodge's formulas, in contrast to what other studies have stated in small cohorts. Patients with monosomy 45,X show no clinically relevant QTc prolongation compared to other karyotypes.