By Edward P. Gerstenfeld, MD
Professor of Medicine, Chief, Cardiac Electrophysiology, University of California, San Francisco
Dr. Gerstenfeld does research for Biosense Webster, Medtronic, and Rhythmia Medical.
Pappone C, et al. Wolff-Parkinson-White syndrome in the era of catheter ablation: Insights from a registry study of 2169 patients. Circulation 2014;130:811-819.
The authors prospectively collected data from a single center in Italy including symptomatic and asymptomatic Wolff-Parkinson-White ([WPW]pre-excited) patients. All included patients underwent baseline electrophysiological study (EPS). Primary endpoints were the percentage of patients who experienced ventricular fibrillation (VF) or potentially "malignant" arrhythmias. Among 2169 enrolled patients, 1001 (550 asymptomatic) did not undergo ablation and 1168 (206 asymptomatic) underwent ablation. There were no differences in clinical and electrophysiological characteristics between the two groups, except for symptoms. In the no-ablation group after a median follow-up of 22 months, VF occurred in 15 (1.5%) patients (13/15 children, 13/15 asymptomatic), and was associated with a short accessory pathway antegrade refractory period (P < 0.001) and atrioventricular reentrant tachycardia initiating atrial fibrillation (P < 0.001). Warning symptoms included presyncope or dizziness. "Malignant" arrhythmias occurred in another 78 patients (48 asymptomatic). In the ablation group, ablation was successful in 98.5%, and no patients developed malignant arrhythmias or VF over the 8-year follow-up. Major complications occurred in only one patient (0.08%) consisting of complete heart block. Untreated patients were more likely to experience malignant arrhythmias and VF (log-rank P < 0.001) compared to patients who underwent ablation. Asymptomatic untreated patients were more likely to develop VF compared to untreated symptomatic patients (log-rank P = 0.008). The authors concluded that the prognosis of the WPW syndrome does not depend on symptoms. Radiofrequency catheter ablation performed after electrophysiological testing was of benefit in improving the long-term outcomes.
COMMENTARY
The management of the asymptomatic patient with pre-excitation has been controversial for decades. The current guidelines recommend catheter ablation as a Class I indication only for symptomatic patients, with catheter ablation for asymptomatic patients considered a IIA indication. The classic teaching is that the risk of cardiac arrest in the asymptomatic patient is low (0.1%); however, the risk of a complication from ablation, including complete heart block requiring permanent pacing, vascular injury, pneumothorax, or even death, is similarly low (0.1-0.2%) but finite, favoring a conservative watchful waiting approach. Catheter ablation for asymptomatic patients has generally been reserved for patients with "high risk" occupations, including airline pilots, commercial bus drivers, and those in the armed forces.
The current study reports an incidence of VF in 15 (1.5%) asymptomatic patients followed for 8 years, higher than that of previous studies. While all the patients in the study were resuscitated from cardiac arrest without neurologic sequelae, the occurrence of VF should not be minimized. Asymptomatic patients also had a higher incidence of VF compared to symptomatic patients. The limitations of the current study are that it is a single-center study at a center with significant ablation experience, limiting the occurrence of complications. The higher incidence of cardiac arrest in asymptomatic patients in this study is likely in part related to selection bias, with a higher number of symptomatic patients electing to undergo ablation. Despite the occurrence of VF in 1.5% of patients, all were resuscitated and survived.
Over the past decade, significant advances in the efficacy and safety of catheter ablation have occurred, including use of intracardiac echocardiography to guide transseptal puncture and cryoablation to minimize the risk of heart block. Have these advances tipped the balance in favor of catheter ablation for asymptomatic patients? In an accompanying editorial, Dr. Geoge Klein advocates the conservative approach. However, I am not sure this remains valid. Is it reasonable to tell a patient and family that if they were a commercial pilot, catheter ablation would be recommended, but for an individual who is not at risk of crashing a plane, the risk of sudden death is acceptable? Is the additional lifelong concern when any lightheaded episode or palpitation occurs necessary? The vast majority of WPW ablation procedures are straightforward and in experienced centers, the risk is quite low. The success rate is > 98% and frees the patient from need for future concern of health care needs. Certainly a consultation with an electrophysiologist for asymptomatic WPW is warranted. For patients with intermittent pre-excitation or pre-excitation that abruptly resolves on an exercise treadmill test, the risk of sudden death is essentially zero and no treatment is necessary. For patients with persistent pre-excitation, a thorough discussion of the risks and benefits with the patient is necessary. For nonseptal accessory pathways, electrophysiology study and catheter ablation are reasonable. For septal pathways where the risk of heart block is higher, EPS remains reasonable, with ablation guided by patient age, accessory pathway characteristics, and the risk of heart block. In the patient who elects a "watchful waiting" approach, he/she should be instructed to seek medical attention immediately for any symptoms of palpitations or presyncope.
