Preoperative arrhythmia evaluation and treatment for Ebstein's anomaly patients
Approximately one percent of congenital heart disease patients suffers from Ebstein's anomaly, a disorder characterized primarily by displacement of the tricuspid valve. The leading approach for Ebstein's repair is the cone procedure1, in which the valve's leaflets are freed from the cardiac wall and twisted into a cone shape that promotes normal blood flow to the right ventricle.
"There was no good operation for Ebstein's for a long time," says Edward Walsh, MD, chief of the Division of Cardiac Electrophysiology in Boston Children's Hospital's Heart Center. "It's remarkable how well these patients do now compared to past surgeries."
Walsh's interest in Ebstein's stems from the atrial and ventricular arrhythmias commonly associated with it. The tissue spanning right atrium and ventricle is electrically abnormal in Ebstein's. "The tissue is thin and scarred and doesn't conduct well," Walsh explains.
Currently, the standard practice is to include arrhythmia screening as part of Ebstein's patients' standard post-surgical care, as one would for any patient with a congenital heart anomaly. However, Walsh has started to advocate for a more aggressive preemptive approach to arrhythmia care in patients with Ebstein's, one that may help prevent later occurrences of sudden cardiac death.
Treating before treating
As Walsh and his collaborators, including Boston Children's Chief of Cardiac Surgery Pedro Del Nido, MD, report in Heart Rhythm2, preoperative electrophysiologic studies (EPS) on Ebstein's patients provide an opportunity to discover and correct rhythm dysfunctions preemptively, reducing the risk of sudden cardiac death following repair of the tricuspid anatomy.
"Arrhythmia problems are common in Ebstein's, and you don't want to be surprised after surgery," Walsh says. "So when we have a patient come in for the cone procedure, we go looking for rhythm troubles and try to treat them before going into surgery."
The Heart Rhythm paper presents the results of a retrospective review of the outcome of 74 Ebstein's anomaly patients who underwent the cone procedure at Boston Children's between 2006 and 2012. Of them, 42 underwent preoperative EPS.
EPS detected arrhythmias in 29 of the 42 patients. Many of these patients—23—had previously known or suspected arrhythmias. However, EPS revealed arrhythmias in eight patients with no prior history of electrophysiological concerns.
Seventeen of the EPS-positive patients underwent catheter ablation at the time of their arrhythmia evaluation; 35 also underwent ablation during their cone surgery. The choice of catheter versus surgical ablation was determined based on the specific arrhythmia, substrate location, patient age and other factors.
The promise of a proactive approach
Given the number of arrhythmias revealed anew by EPS, Walsh isn't concerned that this more aggressive preoperative approach will lead to overtreatment. "The arrhythmias we found are not ones that will remain silent in the long run," he cautioned. "These are problems that will cause morbidity or mortality sooner or later."
Walsh is quick to note that this was an observational study, not a trial designed to draw statistical conclusions. "We set out to show that in our experience you could detect arrhythmias preoperatively in patients with Ebstein's anomaly, and that you could treat them either in a catheterization or surgical setting," he said.
That being said, the results do suggest that this more aggressive approach to preoperative evaluation and treatment could potentially benefit Ebstein's patients in the long run. "If you take care of arrhythmias preoperatively, patients may fare much better postoperatively," Walsh says.
1. da Silva et al. "The cone reconstruction of the tricuspid valve in Ebstein's anomaly. The operation: early and midterm results." J Thorac Cardiovasc Surg. 2007; 133(1):215-23.
2. Shivapour JK et al. "Utility of preoperative electrophysiologic studies in patients with Ebstein's's anomaly undergoing the cone procedure." Heart Rhythm. 2014; 11(2):182-6.