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.