SCN5A Mutation Unveiled By Ventricular Tachycardia in Late Pregnancy: Diagnosis and Management

Document Type

Conference Proceeding

Publication Date

10-2025

Publication Title

Chest

Abstract

INTRODUCTION: Ventricular tachycardia (VT) during pregnancy is rare, occurring in approximately 2 per 100,000 hospitalizations. This risk increases significantly in women with structural heart disease, such as congenital heart defects or cardiomyopathies, or primary electrical abnormalities like SCN5A mutations. This case highlights the challenges and successful management of VT in pregnancy, revealing an underlying SCN5A mutation, a scenario with limited precedent in the literature. CASE PRESENTATION: A 35-year-old G5P1031 at 36w3d presented with transient loss of consciousness preceded by tinnitus, dizziness, nausea, and blurred vision. She denied chest pain, palpitations, or dyspnea. Her history included intermittent tachyarrhythmias but no prior cardiac interventions during this pregnancy. Vitals: BP 113-144/66-80 mmHg, HR 80-110 bpm, SpO2 97% on 2L O2 via nasal cannula. She had reassuring fetal status, no labor signs. EKG with Sinus rhythm with right ventricular conduction delay (RSR’ in V1) and prolonged QTc (490 ms). Lab findings: Potassium 3.5 mEq/L, magnesium 1.8 mg/ dL, and Hgb 10.6 g/dL. Holter monitoring at the time revealed a 16-second run of nonsustained ventricular tachycardia correlating with the syncopal episode. An earlier echocardiogram showed an ejection fraction of 60% with no structural abnormalities. She was started on metoprolol 25 mg daily, with aggressive correction of electrolytes to maintain K > 4.5 and Mg > 4. Defibrillator pads were placed for precautionary monitoring. Labor induction was planned at 37 weeks due to gestational hypertension and the arrhythmia episode. Delivery was uneventful, and postpartum imaging, including cardiac MRI and CT coronary angiography, showed no structural abnormalities. Genetic testing confirmed an SCN5A mutation. Postpartum, the patient received an implantable cardioverter-defibrillator (ICD) for secondary prevention and was continued on low-dose betablockers for rhythm control. DISCUSSION: The absence of structural heart disease suggests a predisposition from her SCN5A mutation, unmasked by pregnancy's unique physiologic changes. SCN5A mutations, affecting the Naᵥ1.5 sodium channel, are linked to syndromes like Brugada and idiopathic VT, present in 20%–25% of Brugada cases. Documented cases of SCN5A mutations undergoing pregnancy remain rare, emphasizing the need for further research. Patient's management included targeting potassium >4.5 mEq/L and magnesium >4 mg/dL, thresholds exceeding conventional guidelines. While no pregnancy-specific VT targets are established, these aggressive goals were guided by data from non-pregnant populations. Elevated magnesium levels have been effective in suppressing VT, particularly in torsades de pointes, by prolonging refractory periods and stabilizing cardiac myocyte membranes. Similarly, maintaining potassium above 4.5 mEq/L reduces arrhythmogenic risks. The lack of pregnancy-specific data presents a challenge, but the success in this case suggests these higher thresholds may offer a protective buffer against pregnancy's amplified arrhythmogenic risks. We were able to achieve VT suppression with magnesium and beta blockers. Telemetry and Defibrillator pads ensured safety during high-risk period, while ICD placement addressed long term risks. ICDs remain the gold standard for secondary prevention. CONCLUSIONS: This case highlights the need for more data on pregnancy outcomes in SCN5A mutation carriers and the role of electrolyte management in VT during pregnancy. Successful VT suppression with high magnesium levels suggests this approach is safe and effective when carefully monitored

Volume

168

Issue

4S

First Page

781A

Comments

American College of Chest Physicians CHEST Annual Meeting, October 19-22, 2025, Chicago, IL

Last Page

782A

DOI

10.1016/j.chest.2025.07.462

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