Ablation of Persistent Left Superior Vena Cava in Atrial Fibrillation CaseKey clinical message:This case report discusses the successful ablation of a persistent left superior vena cava (PLSVC) as a trigger for atrial fibrillation. Following cryoballoon ablation and subsequent radiofrequency ablation, the patient experienced no recurrence of atrial fibrillation over a six-month follow-up period, confirmed by monthly ECG and Holter monitoring.Introduction:We report a case of persistent atrial fibrillation (AF) with a persistent left superior vena cava (PLSVC). The patient underwent cryoballoon ablation, improving cardiac function. Six months later, the patient experienced paroxysmal AF and underwent radiofrequency ablation. Intracardiac echocardiography and mapping confirmed PLSVC as the AF trigger. Isolation of the PLSVC successfully terminated AF. No AF episodes occurred during the six-month follow-up.Case Presentation：A 58-year-old female patient was admitted to the hospital on February 22, 2023, due to recurrent palpitations accompanied by shortness of breath that she had experienced for more than three years. The initial electrocardiogram (ECG) indicated atrial fibrillation (AF), and an echocardiogram revealed enlargement of both the left and right atria, along with a decreased ejection fraction (Left Atrial Size [LAS] 50mm, Left Ventricular Diameter [LVD] 55mm, Right Atrial Size [RAS] 39mm, Right Ventricular Diameter [RVD] 35mm, Ejection Fraction [EF] 33%). She underwent her first cryoballoon ablation procedure, after which her heart rhythm returned to normal sinus rhythm.On November 23, 2023, she was readmitted to the hospital due to persistent palpitations that had lasted for over three months. During these episodes, the ECG again showed atrial fibrillation. A follow-up echocardiogram indicated a reduction in the size of both the left and right atria, and the ejection fraction had improved to normal (LAS 39mm, LVD 45mm, RAS 34mm, RVD 29mm, EF 61%).Methods ( Electrophysiological Study and Ablation Procedure )：The patient underwent her first surgery with considerations for heart failure, as her ejection fraction (EF) had decreased, making it difficult for her to tolerate lengthy radiofrequency ablation procedures and intraprocedural saline infusion. Therefore, cryoablation was chosen for treatment. After the procedure, the patient maintained sinus rhythm for six months before experiencing a recurrence of paroxysmal atrial fibrillation.During the patient’s second radiofrequency ablation procedure, pre-operative assessments showed she was in sinus rhythm (Figure 1A). Intracardiac echocardiography (ICE) revealed the presence of a Persistent Left Superior Vena Cava (PLSVC) (Figure 1B). The intracardiac three-dimensional mapping using the Carto 3 system demonstrated electrical reconnection in the left and right pulmonary veins (Figures 1C-F).The ablation steps began with gap ablation within the pulmonary veins, followed by an expansion of the ablation area and linear ablation at the roof (Figure 1G).