Symptomatic arrhythmias in pregnancy remain uncommon but are increasing due to rising maternal age and comorbidities such as hypertension, diabetes, and obesity (1–3). While sinus arrhythmias predominate (104/100,000) (4), clinically significant arrhythmias such as atrial fibrillation/atrial flutter (AF/AFL) and ventricular tachycardia/ventricular fibrillation (VT/VF) (16–24/100,000) carry substantial risks, demonstrating a 5.9% mortality rate compared with 0% in unaffected pregnancies (1, 3, 5). Management principles parallel those in non-pregnant patients but require fetal protection measures (1, 6). Recommendations from the Heart Rhythm Society (HRS) advocate for prompt, definitive therapy—including cardioversion, antiarrhythmic drugs, or catheter ablation—for unstable cases, with stringent fetal monitoring and radiation-minimizing techniques (1). However, therapeutic decisions are often complicated by limited robust data and a paucity of shared clinical experiences (1). In June 2025, our team managed a 32-week pregnant patient with refractory VT following a 16-day course of myocarditis treatment which was unresponsive to adenosine. Considering multidisciplinary evaluations and the patient's willingness, emergency radiofrequency cardiac ablation (RFCA) was performed under 3D electroanatomic mapping, achieving immediate rhythm control. The patient was able to deliver a healthy infant 2 months post-ablation without symptoms or arrhythmia recurrence. The successful outcome supports expanding interventional options when pharmacotherapy fails, although larger studies are needed to standardize protocols. We present this experience in accordance with the CARE Guidelines (2016) (Supplementary Data Sheet 1).

Although the patient presented with symptoms suggestive of an upper respiratory tract infection (URTI), accompanied by elevated troponin and NT-proBNP levels, rapid screening for COVID-19 and influenza virus was negative. While these findings did not definitively exclude myocarditis, the absence of detectable viral pathogens reduced its likelihood as the primary etiology. Notably, the patient recalled that during her initial hospitalization, a consulting cardiologist had raised the possibility of VT, although no ECG documentation was obtained at that time. Given the lack of significant family or personal cardiac history, as well as the absence of structural abnormalities on imaging, the multidisciplinary team concluded that the VT was most likely idiopathic in origin.

The primary diagnoses were as follows:

(1) Cardiac arrhythmia: probable left fascicular VT

(2) Obstetric status: G2P1 at 32 + 0 weeks of gestation by last menstrual period (LMP), post-cesarean scarred uterus

(3) Comorbid conditions: hyperlipidemia and history of peripartum myocarditis (resolved)

Given the failure of pharmacological cardioversion, the refractory nature of the arrhythmia, and potential risks to both maternal and fetal well-being, a multidisciplinary team—including intensivists, cardiologists, obstetricians, pediatricians, and electrophysiologists—conducted an urgent risk–benefit assessment. The patient withheld informed consent for electrical cardioversion due to personal concerns despite detailed discussion. Given the hemodynamic instability and advanced gestational age, the team unanimously advocated for emergent zero-fluoroscopy radiofrequency ablation to minimize fetal radiation exposure while ensuring maternal safety.

Given the absence of significant cardiac history, structural abnormalities on imaging, or metabolic derangements, our multidisciplinary team concluded that the VT in this case was most likely idiopathic in origin. This classification is consistent with existing literature, which indicates that a majority of prenatal VTs are idiopathic, often occurring in the absence of structural heart disease (7).

The patient's clinical course provides valuable insights. The episodic nature of her symptoms, coupled with the recall of a possible VT diagnosis during her initial hospitalization for suspected myocarditis, suggests that the arrhythmic substrate may have been present prior to the acute presentation. While pregnancy is known to exacerbate certain arrhythmias due to hemodynamic and hormonal changes (increased blood volume, cardiac output, and adrenergic sensitivity) (8), the definitive resolution of VT following targeted ablation of a specific fascicular pathway in our patient strongly supports the presence of a primary electrophysiological anomaly rather than a pregnancy-induced one. This is further reinforced by the observed 90% postpartum resolution rate of pregnancy-associated idiopathic VT reported in the literature (6), suggesting that pregnancy often unmasks or aggravates pre-existing substrates rather than creating new ones.

The elevation in cardiac biomarkers (troponin and NT-proBNP) observed in this case, a common feature in both myocarditis and tachyarrhythmias, presented a diagnostic challenge. However, the absence of confirmed viral etiology and the definitive response to ablation make tachycardia-induced demand ischemia a more likely explanation for the biomarker release in this specific patient (9–12). This highlights the importance of maintaining a high index of suspicion for primary arrhythmias even in the context of biomarker elevations, particularly when initial workup for other causes is inconclusive.

Presently, antiarrhythmic drug therapy remains the first-line treatment for arrhythmia during pregnancy (8). However, its use is limited by potential fetal effects and variable efficacy (8, 13). Some physical approaches, such as transesophageal atrial pacing (TAP) and electrical cardioversion, are reproducible and easy to operate, but there are some drawbacks, including low efficiency and easy recurrence within a short time (14, 15). For drug-refractory, hemodynamically unstable cases, our experience adds to the growing body of evidence supporting the safety and feasibility of catheter ablation as a definitive treatment option.

A review of literature identified 45 published cases of prenatal ablation, primarily for SVT, AF, and Wolff–Parkinson–White (WPW) syndrome (12, 15, 16). Most patients in these cases are in their second or third-trimester pregnancy. Notably, only three cases described ablation for VT associated with structural heart disease after failed pharmacological therapy and transabdominal pacing (TAP) conversion (16, 17). Our case is unique in demonstrating successful emergency zero-fluoroscopy ablation for idiopathic VT during pregnancy. Alongside other reports, which have documented no major maternal or fetal adverse events, this case helps to solidify the role of this intervention in select high-risk scenarios. Continued advancements in zero-fluoroscopy techniques are likely to expand their applicability in the pregnant population.

In this case report, the patient presented with recurrent VT that was refractory to pharmacological cardioversion, necessitating emergency RFCA. This case represents the first to advocate for the use of cardiac RFCA and further supports the feasibility of emergency zero-fluoroscopy ablation for life-threatening prenatal arrhythmias under multidisciplinary coordination. Future studies with long-term follow-up are needed to further elucidate the natural history of idiopathic VT in similar patient populations.

Beyond presenting a successful management of a rare and life-threatening condition, this case offers several broader clinical implications. First, it suggests that idiopathic VT should be considered in the differential diagnosis of pregnant women with unexplained troponin elevation, warranting comprehensive arrhythmia monitoring. Second, it exemplifies the critical need for pre-emptive, deeply integrated multidisciplinary teams ready to deploy advanced, minimally invasive interventions like zero-fluoroscopy ablation. This case strengthens the argument for considering such ablation not merely as a rescue therapy but as a definitive first-line intervention for drug-refractory VT in late-stage pregnancy. Finally, the patient's perspective underscores how respecting patient autonomy can guide clinicians toward more innovative and acceptable solutions. Future efforts should focus on developing standardized protocols that incorporate these insights to improve care for similar high-risk patients.

“The sudden onset of VT during my third-trimester pregnancy was terrifying, and I couldn't stop wondering if I had done something harmful to my body in the past year. When medication failed to restore my normal rhythm, I was faced with an impossible choice. Fear for my baby's safety led me to decline electrical cardioversion, and both my husband, and I felt utterly helpless. The proposal of a zero-fluoroscopy ablation offered a beacon of hope. Thank god, the procedure was successful, and my immense relief was compounded two months later when I delivered a healthy baby boy via cesarean section. The discomfort was gone, and the arrhythmias have not recurred. I am eternally grateful to the medical team for their innovation and care during the most frightening time of my life.”