Introduction
KEY TEACHING POINTS
Key Teaching Points
•
Ebstein’s anomaly is a rare congenital heart disease that is frequently associated
with supraventricular tachycardia (accessory pathway–related arrhythmia, atrial flutter,
and atrial fibrillation).
•
Radiofrequency catheter ablation could be an alternative treatment for drug-refractory
paroxysmal atrial fibrillation in patients with Ebstein’s anomaly who do not yet require
corrective surgery.
•
Pulmonary vein trigger and left atrial substrate might still be the main pathogenesis
of atrial fibrillation, even in patients with apparent right-side heart diseases such
as Ebstein’s anomaly.
Ebstein’s anomaly is a rare congenital heart disease in which the tricuspid valve
is displaced toward the apex of the right ventricle (RV). It is commonly associated
with atrial arrhythmia, especially Wolff-Parkinson-White syndrome. In fact, up to
20% of patients with Ebstein’s anomaly have 1 or more accessory pathways owing to
tricuspid valve malformation,
1
most of which are located along these tricuspid valves.2, 3 In addition, atrial fibrillation
(AF) can develop with aging.
4
Although the success rate of catheter ablation of an accessory pathway is lower in
patients with Ebstein’s anomaly than in the general population, catheter ablation
is the most favorable treatment strategy.
5
In patients with AF, however, concomitant surgical ablation at the time of corrective
surgery is preferred. To the best of our knowledge, there has been no report of catheter
ablation without corrective surgery for AF in a patient with Ebstein’s anomaly. Here,
we present the case of an adult patient with Ebstein’s anomaly who developed drug-refractory
and intolerant paroxysmal AF, but did not yet require corrective surgery.
Case report
A 39-year-old man visited the emergency department for recurrent palpitations. He
had been diagnosed with Ebstein’s anomaly (Carpentier type B) at 27 years of age.
He had a history of receiving radiofrequency catheter ablation (RFCA) for Wolff-Parkinson-White
syndrome at 38 years of age at our clinic. A single bidirectional atrioventricular
accessory pathway was identified in the right lateral region of the true anatomical
tricuspid annulus. This accessory pathway was treated successfully with RFCA using
a 3-dimensional (3D) mapping system (EnSite Velocity, St. Jude Medical). Subsequently,
the patient had no palpitations, and electrocardiography revealed no sign of ventricular
pre-excitation. However, palpitations recurred after 6 months, the characteristics
of which were slightly different from the previous palpitations associated with Wolff-Parkinson-White
syndrome. Electrocardiography revealed AF without ventricular pre-excitation. We initially
prescribed a beta-blocker, sotalol, and amiodarone, but the AF was not controlled
during the following 5 months. Because the patient was highly symptomatic (he visited
the emergency department once a month, and direct-current cardioversions were performed
twice during 5 months), we considered ablation therapy via a catheter or surgical
approach.
Echocardiography was performed on admission. The right heart was globally enlarged
and the function of the RV was decreased. The insertion of the septal tricuspid valve
was markedly displaced toward the apex (the linear distance between this point and
the septal insertion of the anterior mitral leaflet was approximately 57 mm). Motion
of the anterior tricuspid leaflet was limited because of tethering at multiple points
on the free wall of the RV. On color Doppler echocardiography, single tricuspid regurgitation
was noted, which was considered to be moderate based on the color jet area method
(Figure 1). Chamber size and systolic function of the RV were stationary over 10 years.
The patient had no symptoms except for palpitations, and his exercise capacity was
tolerable and stationary. Based on these findings, corrective surgery was not yet
required, and the patient did not want open heart surgery. Therefore, we decided to
perform RFCA for drug-refractory paroxysmal AF.
After we obtained written informed consent, dexmedetomidine and midazolam were administered
for deep sedation. The entire procedure was performed via peripheral venous access
and transseptal access across the interatrial septum to approach the left atrium (LA).
Intravenous heparin was administered to maintain an activated clotting time >250 s
after transseptal puncture. A multielectrode duodecapolar catheter was placed in the
right atrium (RA) and coronary sinus via the left femoral vein. A 20-pole circular
mapping catheter was used for both mapping and confirmation of pulmonary vein antrum
isolation (PVAI). Ablations were performed using an open irrigated-tip catheter, and
a 3D mapping system was used to guide the procedure. The size of the RA was huge (anteroposterior
diameter, 74 mm), while the LA was slightly enlarged (anteroposterior diameter, 41
mm). We checked the trigger of AF before ablations and found the atrial premature
beat from the right inferior pulmonary vein that triggered the AF. Circumferential
PVAI was achieved successfully. However, sustained AF was induced by rapid atrial
pacing after PVAI. Therefore, linear ablations of the roof, mitral isthmus, and cavotricuspid
isthmus (CTI) were performed (Figure 2). Linear ablations of the roof and mitral isthmus
were performed according to standard techniques.
6
Ablations of CTI were difficult because of the patient’s huge RA and atrialization
of part of the RV. Nonetheless, bidirectional block of the CTI was achieved successfully.
The patient’s AF was organized and converted to atrial flutter and finally terminated
during CTI ablation. We rechecked and confirmed the PVAI and bidirectional block of
the roof and CTI line. However, bidirectional block of the mitral isthmus could not
be achieved. Neither sustained AF nor atrial flutter (AFL) was induced after ablation.
The procedure was completed without any complications. Low-dose sotalol (20 mg twice
daily) was prescribed postoperatively because of the persistent arrhythmogenic substrate
of the RV and the failed linear ablation of the mitral isthmus. The patient had no
further palpitations, and there was no documented AF or AFL during the 15-month follow-up.
Postprocedure and 1-, 3-, 6-, and 12-month Holter monitoring did not show any sustained
paroxysmal AF or AFL.
Discussion
Ebstein’s anomaly is a rare congenital heart disease that is frequently associated
with supraventricular tachycardia. Although accessory pathway–related arrhythmia is
most common—occurring in 6%–30% of patients with Ebstein’s anomaly—AFL or AF also
may develop. AFL is usually observed after surgery involving atriotomy or other scar
tissue. Catheter ablation is the treatment of choice for AFL, and has a short-term
success rate of approximately 80%–90% since the introduction of 3D mapping and irrigated-tip
ablation catheter.7, 8 AF also may be observed in Ebstein’s anomaly, especially in
older patients, the mechanism of which may be explained by secondary change of RA
myocardium from previous cardiac surgery or chronic hemodynamic stress toward the
LA.8, 9 Antiarrhythmic drugs may be prescribed, but their use is restricted by structural
heart disease. Furthermore, the long-term prognosis of medical treatment is poor.
According to American College of Cardiology/American Heart Association guidelines,
5
a biatrial Maze procedure is recommended for patients with Ebstein’s anomaly and AF
who require corrective surgery because of hemodynamic problems. To the best of our
knowledge, there has been no report of RFCA for AF in a patient with Ebstein’s anomaly.
This may be explained by the rare incidence of Ebstein’s anomaly (1 in 20,000 live
births). In addition, most patients with AF require corrective surgery for hemodynamic
reasons. In contrast, our patient developed AF when corrective surgery was not yet
required. Therefore, we believe there is a group of patients with Ebstein’s anomaly
and AF who do not yet require corrective surgery. In the present case, we performed
RFCA successfully without any procedure-related complications, and there was no recurrence
of AF or AFL during the 15-month follow-up. Our RFCA strategy focused on the LA, similar
to patients with AF without structural heart disease. It seems that the main cause
of AF in patients with Ebstein’s anomaly is a huge RA; thus, RFCA focusing on the
LA was not effective. However, our results of RFCA were satisfactory, suggesting that
the pulmonary vein trigger and LA substrate are still main causes of AF in patients
with congenital heart disease, such as Ebstein’s anomaly. Although it is difficult
to modify the substrate of a huge RA, modification of the pulmonary vein trigger and
LA substrate with congenital heart disease is achievable. Some may doubt the efficacy
of RFCA because of the patient’s concomitant use of an antiarrhythmic drug (sotalol).
However, sotalol was not effective before RFCA. Thus, at the very least, RFCA successfully
reduced the burden of AF until it responded to the antiarrhythmic drug.
Conclusion
Based on this case, RFCA could be an alternative treatment for drug-refractory paroxysmal
AF in patients with Ebstein’s anomaly who do not yet require corrective surgery. In
addition, our case highlights the importance of the pulmonary vein trigger and LA
substrate in the pathogenesis of AF even in patients with apparent right-side heart
diseases such as Ebstein’s anomaly.