Procedural outcomes are difficult to summarize, and procedures are difficult to compare to one another for many reasons, including that the reports have used:
- Different duration of follow-up
- Different means of determining that AF has returned
- Many other differences in defining a successful outcome
The 2007 Consensus Document (Calkins 2007) addresses the issue of outcomes data at length:
When considering the published literature on catheter ablation of AF, it is important to recognize that until the writing of this Consensus Report, there has been no standardization in the design of clinical trials of AF ablation. There are many important aspects of an AF ablation trial that can impact the results. Among the most important is the patient population. It is now well recognized that the outcomes of AF ablation differ considerably depending on whether patients have paroxysmal, persistent, or longstanding persistent AF. Similarly, variables such as age, concomitant cardiac disease, and LA size are important determinants of outcome. Other important considerations are the duration of the blanking period, the frequency and intensity of arrhythmia monitoring, whether patients with atrial flutter during follow-up are classified as successes or failures, the use of antiarrhythmic drugs, and the frequency and timing of performance of repeat ablation procedures. Each of these factors plays a role in how a particular study defined “success.” Whereas some studies have defined success as freedom from symptomatic AF during follow-up, other studies have defined success as freedom from symptomatic and asymptomatic episodes of AF. A third definition of success employed by other studies is a greater than 90% reduction of AF burden, and a fourth definition of success is the proportion of patients free of AF each month of monitoring during follow-up. Each of these definitions can be further modified based on whether patients who remain on antiarrhythmic drugs at follow-up are classified as having had a successful ablation procedure, a partially successful ablation procedure, or a failed ablation procedure. It is also important to recognize that the frequency of detection of asymptomatic AF is directly dependent on the duration and intensity of arrhythmia monitoring during follow-up.
Summary of the Efficacy of Catheter Ablation of Atrial Fibrillation
The results of the studies and surveys reviewed above provide substantial evidence of the efficacy of catheter ablation for treatment of patients with AF. However, it is also clear that outcomes vary considerably. As noted previously, potential factors that may impact outcome include: (1) differences in technique, (2) differences in follow-up and definitions of success, (3) differences in the use of antiarrhythmic therapy, (4) differences in experience and technical proficiency, and so forth. This consensus document should be utilized by future investigators designing clinical trials to further define the efficacy and safety of catheter ablation of AF in a variety of patient populations.
There have been no long-term studies of the results of the minimaze procedures. Regarding catheter ablation, the consensus document summarizes the largest report as follows:
The outcomes of nearly 9,000 AF ablation procedures were reported by these centers. More than one ablation procedure was performed in 27% of patients. The success rate, defined as freedom from symptomatic AF in the absence of antiarrhythmic therapy, was 52%. An additional 24% of patients were free of symptomatic AF in the presence of a previously ineffective antiarrhythmic drug. The mean duration of follow-up of these patients was 12 # 8 months. The incidence of major complications was 6%.
With those caveats in mind, the following data are presented.
|Study||# of Pts.||FU (yrs.)||Free of AF||Free of AF
|2000||5||-||-||23.8% / 5yrs||8.9% / 5yrs|
| Wolf Minimaze