The added value of the electrocardiogram in Noonan syndrome

• Published in: Cardiology in the young 2022-06, Vol.32 (6), p.936-943
• Main Authors: Vos, Eefke, Leenders, Erika, Werkman, Sterre R., Udink ten Cate, Floris E. A., Draaisma, Jos M. T.
• Format: Article
• Language: English
• Subjects: Abnormalities; Anomalies; Cardiomyopathy; Defects; Deviation; EKG; Electrocardiography; Electrophysiology (EP); Genes; Genetic disorders; Heart Defects, Congenital - diagnosis; Heart Defects, Congenital - genetics; Humans; Kinases; Mutation; Noonan Syndrome - diagnosis; Noonan Syndrome - genetics; Noonan's syndrome; Original Article; Patients; Pulmonary Valve Stenosis; Retrospective Studies; S waves; Stenosis; Subgroups; Ultrasonic imaging
• ISSN: 1047-9511; 1467-1107
• DOI: 10.1017/S1047951121003310

Noonan syndrome is a genetic disorder characteried by short stature, typical facial features, developmental delay, and CHD. In this single-centre retrospective study, we analysed typical Noonan syndrome-related electrocardiographic features in 95 patients with clinically and molecularly confirmed Noonan syndrome. Typical Noonan syndrome-related electrocardiographic features are left axis deviation, small left precordial R-waves, large right precordial S-waves, abnormal Q-wave, and abnormal wide QRS complex. In this representative cohort, CHD was found in 59 patients (62.1%) and typical Noonan syndrome-related electrographic features in 60 patients (63.2%). The typical Noonan syndrome-related electrographic features were also increased over baseline in patients without CHD (41.7%). Of all 95 patients, left axis deviation was seen in 46.3%, small left precordial R-waves in 30.5%, large right precordial S-waves in 5.3%, and abnormal Q-wave and wide QRS complex in 2.1%. There was no significant difference in the frequency of the individual-specific electrographic features between the group with CHD and the group without CHD. However, there were significantly more patients with a small left precordial R-wave in the subgroup with pulmonary stenosis compared to patients without pulmonary stenosis. Conclusion: Specific Noonan syndrome-related electrographic features are frequently present in patients with Noonan syndrome, also in the absence of CHD. These results suggest that there may be a continuum of cardiac anomalies from overt CHD to milder abnormalities that are only seen on electrocardiogram.