Electrocardiographic Evaluation in Patients With Spinal Muscular Atrophy: A Case-Control Study

Background: This study aimed to show the impairment of autonomic cardiac conduction causing bradycardia and/or electrocardiographic alterations in children affected by spinal muscular atrophy type 1 and 2 (SMA 1 and 2). Methods: We included 25 spinal muscular atrophy patients, admitted from November 2016 to May 2017. All patients underwent an electrocardiographic examination and we studied PR and QRS intervals, P-waves and QRS amplitudes, and heart rate in spinal muscular atrophy patients compared to a control group. Results: In all patients, we found longer PRi and QRSi (P <.05), lower P-wave and QRS complex amplitudes (P <.01), and a decreased heart rate (P <.01) with respect to controls. When we divided our patients into SMA1 and SMA2 subgroups, we found that statistical differences were maintained for P-wave and QRS complex amplitudes and heart rate, but not for PRi and QRSi with respect to controls. Conclusion: We suggest the hypothesis of SMN expression on cardiac tissue condition and/or autonomic cardiac conduction.