Ablation Procedures
Supraventricular arrhythmias in both groups were AVNRT, AVRT, WPW, and atrial tachycardia arrhythmias (Table 1). In the zero-fluoroscopy group, 87.5% of procedures utilized electroanatomic mapping with and without intracardiac echocardiography, with 68.75% utilizing Ensite NavX and the remainder CARTO as the electroanatomic mapping tool. The majority of clinical arrhythmias in the zero-fluoroscopy group arose from the right side with six cases reported left-sided etiologies of arrhythmias and 3 requiring transseptal approaches. Similarly, the majority of cases in the minimal fluoroscopy group had culprit arrhythmias originating from right-sided regions (Table 2) Though there was no uniform documentation of the use of local versus general anesthesia in these cases, only two reported the use of generalized anesthesia in the zero-fluoroscopy group.
Results :
The majority of the ablations in the study group were performed in the second and third trimester of pregnancy, regardless of fluoroscopy use. The mean gestational age was 21.1 ± 7.3 weeks
weeks with a maternal age of 31 ± 8 years in the zero-fluoroscopy group versus a mean maternal age of 27 ± 4 years weeks and a gestational age of 25.8 ± 7.1 weeks in the minimal fluoroscopy group (Table 3). There was no statistical significance between the means for both groups in respect to maternal and gestational ages at time of ablation therapy. On average, patients undergoing zero-fluoroscopy ablations were at younger gestational ages (p = 0.0591) in comparison to the minimal fluoroscopy group, though the former had a greater maternal age (p = 0.0597). Three were of advanced maternal age, defined here as above 35 years old, in the zero-fluoroscopy group with no reported cases in the minimal fluoroscopy group.
Most patients initially presented with symptoms of palpitations, dizziness, and tachycardia. The majority had previously been on a beta-blocker regimen prior to recurrence. Three cases described the prior use of amiodarone, sotalol, or digoxin for arrhythmias.
A comparative breakdown of ablations performed based on etiology, location of arrhythmia, and approach for left sided arrhythmias can be seen in Table 4. All ablation procedures led to successful ablation of the culprit supraventricular tachycardia. There was no statistically significant difference in arrhythmia type including AVRT, AVNRT, and AT (p-values of 0.739, 0.601, 0.922, respectively.) In addition, there was no statistically significant difference between the two groups with respect to left sided procedures (p=0.792). Lastly, analysis of transeptal versus retrograde aortic approaches for left-sided ablations in both groups did not demonstrate statistical significance (p-values of 0.375 and 0.856, respectively).
There were no reported immediate perioperative complications and all reported fetal outcomes resulting in the successful delivery of healthy children. In addition to the advantage of zero exposure to ionizing radiation to the fetus and mother, all documented peri-procedural outcomes, both immediate and long-term complications were negligible.
Discussion :
This is the first systematic review comparing minimal to zero-fluoroscopic ablation for gestational supraventricular arrhythmias and demonstrates comparable safety and outcomes. Normal physiologic changes in pregnancy i.e., increased effective circulating volume, cardiac output, and resting heart rate may attribute to arrhythmogenesis. Sustained supraventricular tachycardias (SVTs) may occur in up to 1.3% of all pregnant women without structural heart disease and those with a history of arrhythmias are at significant recurrence risk2.
Antiarrhythmic drugs, though effective, are not without risk in pregnancy as many cross the placental barrier with equivocal side effects. Most common pharmacologic options for gestational SVT remain a Food and Drug Administration category C, meaning risks could not be ruled out. The current lack of randomized trials and systematic data of the efficacy and safety of anti-arrhythmic drugs in pregnancy have caused a recent shift towards therapeutic catheter ablation procedures3. However, theoretical fluoroscopic radiation exposure to the fetus remains a particular concern of ablation therapy, especially in the first trimester during organogenesis4. Though the exposure levels for fetal abnormalities varies, a reasonable threshold for concern on fetal exposure is 50 mGy, a dose which has not been associated with fetal anomalies or pregnancy loss24. One study demonstrated that with proper abdominal shielding, theoretical fetal exposure during a catheter ablation procedure was <1 mGy25. Nevertheless, given the risks above, fluoroscopic free ablation is gaining wider acceptance as an alternative to treat pregnant patients with refractory arrhythmias26.
Our baseline demographic data demonstrated similar findings in both groups including clinical presentations, with most arrhythmias consisting of Wolff-Parkinson-White, AVNRT, and atrial tachycardia. The majority of arrhythmias were right-sided in etiology with initial presentations of symptomatic tachycardia. Utilization of electroanatomic mapping with or without concomitant intracardiac echocardiography in the zero-fluoroscopy group were utilized in 87.5% of the cases. Furthermore, there was a trend towards a statistically significant difference between both maternal and gestational ages at time of ablation therapy. There were more zero-fluoroscopic ablations being performed at earlier gestational times, with minimal fluoroscopic ablations completed later in the third trimester. These findings are reflective of the inherent benefits of utilizing no ionizing radiation with zero-fluoroscopic procedures. Our findings demonstrated equal efficacy rates of successful ablation when compared to the minimal fluoroscopy group. There was no significant difference in the etiology of arrhythmias, whether it was right or left sided. In addition, there was similar rates of transeptal and retrograde aortic approaches for left-sided ablations. Regardless of techniques, there were equal successful outcomes in both groups. There were no documented immediate or long-term perioperative complications in the zero-fluoroscopy group, including delivery outcomes.
In rare cases where the culprit arrhythmia is refractory to both medical and ablative therapy or the patient is a poor candidate for ablations, sustained control of maternal tachyarrhythmias should ultimately be prioritized in the setting of hemodynamic compromise. Strategies may include initiation or escalation of pharmacotherapy with close inpatient monitoring and consideration of a timely cesarean section5. Ultimately, it is imperative to have shared decision making and collaboration amongst cardiology, maternal fetal medicine and obstetric specialists to ensure maximum safety to both mother and fetus.
One major limitation of our review was the lack of uniform documentation as all data points were derived from individual case reports or series, including use of anesthesia, duration of post-procedural follow up, obstetric complications, and prior pharmacologic strategies for rhythm control.
Our study shows that zero-fluoroscopy catheter ablation for supraventricular tachycardia ablation in pregnancy using current electroanatomic mapping systems with or without ICE have equivalent safety and efficacy compared to minimal fluoroscopy ablations, while eliminating the risk of ionizing radiation exposure to both the mother and fetus.