AF Ablation and the Importance of Operator Experience

Previous issues of this editorial have separately covered two related topics: complications related to catheter ablation procedures for atrial fibrillation (AF),¹ and the minimum clinical activity for electrophysiologists to maintain procedural proficiency.² The first editorial was based on the 2009 Worldwide Survey published by Cappato et al³ that found that the mortality rate associated with catheter ablation for AF was only 0.1%. Although the data were based on a retrospective case series and a physician survey, it appeared that the mortality rate associated with the procedure was acceptable. A second editorial in 2011 tried to address the issue of the minimum amount of time interventional electrophysiologists should spend doing cases in order to keep up their skills. It was based on an informal survey of practicing electrophysiologists who were asked to answer the following question: “In your judgment, how many days per month should an interventional electrophysiologist perform EP procedures to maintain expertise in 2011?” The response was a mean of 8.0 ± 2.7 days (median 8, range 4-12 days) to maintain expertise. In other words, electrophysiologists who are performing the full range of interventional EP procedures should be spending at least two days per week in the EP lab. 

A new study by Deshmukh et al in the September 2013 issue of Circulation addresses the issue of maintenance of competency as it applies directly to AF ablation. The group published an analysis of in-hospital complications associated with over 90,000 catheter ablation procedures in the U.S. between 2000 and 2010.⁴ They found the overall complication rate to be 6.3% and a mortality rate of 0.46%. There are limitations to the study, including the use of the Nationwide Inpatient Sample as a data source, and use of nonspecific ICD-9-CM diagnostic codes to identify patients and complications. However, these data are consistent with other recent “real-world” data published since the Cappato survey that suggest that the mortality rate associated with AF ablation is higher than 0.1%. The in-hospital mortality rate in a recent Medicare study was 0.5% and in a California State study was 0.4%. In addition, the Nationwide Inpatient Sample database, which has the word “inpatient” in its title, apparently does also include patients who underwent ablation under “observation” status — a common status for patients who have the procedure.

When facing a study that raises a flag regarding procedural complications, it is important to ask what can be done to make the procedure safer. With regard to that question, the authors in the study by Deshmukh et al looked at procedural experience and showed that annual operator and hospital volumes are very strong predictors of safety. This should not come as a surprise, given that a link between experience and outcomes has been shown in many fields of medicine. What was surprising, however, was how strong that link is for AF ablation. Patients in their study who had an AF ablation procedure performed by a physician who performed the procedure <25 times that year were twice as likely to have a complication. Unfortunately, physicians who performed <25 AF ablation cases that year performed >80% of the procedures. 

The 2012 Heart Rhythm Society/European Heart Rhythm Association/European Cardiac Arrhythmia Society Expert Consensus Document on catheter ablation for AF recommends that electrophysiologists who perform ablation for AF should perform at least 50 procedures during fellowship training and then should perform “several procedures for AF per month if they intend to remain active in this area.” This recommendation is supported by the Deshmukh study, which found that physicians who perform <25 AF ablation procedures per year were twice as likely to have a complication. This is critical data that should not be ignored. Patients with AF should not ignore the relationship between operator experience and quality outcomes, and neither should those involved in hospital credentialing.

References

1. Knight BP. Mortality and AF ablation. EP Lab Digest. 2009;8:4.
2. Knight BP. Staying on your toes in the EP lab. EP Lab Digest. 2011;7:5.
3. Cappato R, Calkins H, Chen SA, et al. Prevalence and causes of fatal outcome in catheter ablation of atrial fibrillation. J Am Coll Cardiol. 2009;53:1798-1803.
4. Deshmukh A, Patel NJ, Pant S, et al. In-hospital complications associated with catheter ablation of atrial fibrillation in the United States between 2000 and 2010. Analysis of 93 801 procedures. Circulation. 2013;128:2104-2112.