Long QT syndrome presenting as convulsions in a preeclamptic patient: a case report

Background Eclampsia is the leading cause of convulsions in patients with preeclampsia. To the best of our knowledge, convulsions secondary to long QT syndrome (LQTS) in the setting of preeclampsia have been reported only rarely. The overlapping clinical manifestations of these two conditions make differential diagnosis challenging. Delayed recognition and inadequate management may place patients at high risk of sudden cardiac death. Case presentation A 31-year-old pregnant woman at 35 + 4 weeks of gestation was initially diagnosed with acute heart failure complicated by preeclampsia and transferred to our institution after initial intensive therapy. After her cardiac function stabilized, a cesarean section was scheduled. Immediately after being positioned, the patient developed sudden syncope and convulsions, which were initially misdiagnosed as eclampsia. Recurrent syncope and persistent convulsions occurred on the second day postpartum. Electrocardiogram monitoring detected torsade de pointes that rapidly deteriorated into ventricular fibrillation. Emergency electrical defibrillation and cardiopulmonary resuscitation were performed, and sinus rhythm was successfully restored. The patient subsequently developed respiratory depression and received endotracheal intubation and mechanical ventilation. A repeat electrocardiogram showed significant prolongation of the corrected QT interval. The patient was extubated the next day with no recurrent convulsive episodes. Retrospective analysis of cardiac recordings captured during the initial convulsive episode revealed non-sustained ventricular tachycardia (NSVT) that spontaneously reverted to sinus rhythm within seconds. Ultimately, the patient's convulsions were attributed to malignant arrhythmias triggered by a prolonged QTc interval in the context of preeclampsia. Conclusion Preeclampsia combined with LQTS is a rare and life-threatening, yet preventable, clinical entity. It is frequently misdiagnosed as eclampsia, which often leads to improper management. Clinicians should maintain high vigilance for this comorbidity, achieve early identification, and initiate prompt intervention to prevent sudden cardiac death.