Ablation Procedure Follow-up and Definitions of Success

Christopher Piorkowski

Gerd Hindricks

Hans Kottkamp

Curative treatment of atrial fibrillation (AF) is one of the major challenges of today’s electrophysiology. The growing knowledge of initiating triggers and perpetuating substrate has led to the development of potentially curative catheter ablation procedures (1, 2, 3).

Ideal treatment outcomes would be a complete cure from the arrhythmia in most of the patients, and in case of AF recurrences a reliable patient perception indicative for these recurrences. However, catheter ablation of AF does not always result in such a binary outcome. Complex clinical presentations regarding the occurrence, duration, and perception of AF recurrences make it difficult to define and measure ablation success.

One major challenge of postinterventional management can be seen in the transformation of patients with previously symptomatic AF into patients with asymptomatic recurrences. However, other changes of arrhythmia characteristics, such as episode duration, need to be considered for definition of ablation success as well. Recognizing these challenges more and more, new technologies such as 7-day Holter ECG or transtelephonic ECG monitoring have been applied to improve an objective follow-up after AF ablation.

This chapter aims to summarize and discuss data available on postinterventional changes in AF characteristics and AF perception as well as methods of follow-up and definition of success.

Development of Asymptomatic Atrial Fibrillation

Asymptomatic or silent arrhythmia is not an uncommon condition in the overall population of patients suffering from AF (4). In population surveys such as the Framingham Study, in antiarrhythmic drug trials, or following pacemaker implantation, asymptomatic AF was reported in up to 50% of the patients evaluated (4,5).

Figure 19.1. Follow-up after circumferential left atrial PV ablation with serial 7-day Holter ECG. The figure consists of a boxplot showing the percentage of asymptomatic AF episodes among all documented AF episodes during the 7-day recording period before ablation, after ablation, and after 3, 6, and 12 months. Median, quartiles, and extreme values are given. The arrows indicate the sudden postinterventional increase of the median of asymptomatic episodes from 0% to 50%. (Modified from Hindricks G, Piorkowski C, Tanner H, et al. Perception of atrial fibrillation before and after radiofrequency catheter ablation: relevance of asymptomatic arrhythmia recurrence. Circulation. 2005;112:307-313.)

However, patients selected for AF catheter ablation have always represented the most symptomatic individuals, because impairment due to AF symptoms is still one of the major indications for catheter interventional treatment. Therefore, one was led to believe that in those patients, symptoms and AF occurrence are reliably linked and postinterventionally can even serve as a valid surrogate parameter to measure recurrences (i.e., ablation failure). Today that picture has changed.

Several clinical trials demonstrated the significant increase in asymptomatic arrhythmia among patients with AF recurrences following catheter interventional ablation procedures. Gerstenfeld et al. and Berkowitsch et al. were the first to report an improved quality of life (SF-36) despite frequent AF recurrences in patients following Lasso-guided pulmonary vein (PV) isolation procedures (6,7).

In patients with circumferential left atrial PV ablation and a follow-up based on serial 7-day Holter ECGs, Hindricks et al. showed that despite the patients being highly symptomatic before ablation with rare asymptomatic episodes, immediately after ablation that situation had changed, with in average 50% of asymptomatic AF episodes (Fig. 19.1). Using their method of follow-up, around 36% of the patients with AF recurrences were completely asymptomatic at 3, 6, and 12 months after ablation (Fig. 19.2) (8).

Figure 19.2. Follow-up after circumferential left atrial PV ablation with serial 7-day Holter ECG. During each follow-up point, the percentage of patients with documented AF recurrences is given. The lower (black) part of each bar represents the relative proportion of patients with only asymptomatic AF recurrences during that 7-day Holter. (Modified from Hindricks G, Piorkowski C, Tanner H, et al. Perception of atrial fibrillation before and after radiofrequency catheter ablation: relevance of asymptomatic arrhythmia recurrence. Circulation. 2005;112:307-313.)

These data could be reproduced from other groups with similar and different methods of follow-up. In a randomized trial comparing circumferential left atrial PV ablation and Lasso guided PV isolation and a follow-up based on serial 7-day Holter ECG, Karch et al. found the percentage of patients with only asymptomatic AF among all patients with AF recurrences at 28% and 47%, respectively (9). Piorkowski et al. used transtelephonic ECG monitoring every other day over 6 months of follow-up after circumferential left atrial PV ablation. Acknowledging all recorded asymptomatic AF recurrences reduced the success rate by about 25% (Fig. 19.3) (10). Introducing a new wireless monitoring device for continuous remote monitoring after circumferential left atrial PV ablation, Vasamreddy et al. reported a reduction of the success rate by about 20% when considering patients with only asymptomatic AF recurrences (11).

The reason for the postinterventional occurrence and increase of asymptomatic AF remains unclear. Invasive treatment of AF per se may result in changes of the arrhythmia perception due to a placebo effect, an ablation-induced change in the arrhythmia pattern, or an ablation-induced modulation of the autonomic nervous system. Additionally, influences of postinterventional medication can be discussed. Nevertheless, the phenomenon of asymptomatic AF recurrences in previously symptomatic patients needs to be considered for an objective assessment of the rhythm outcome after AF catheter ablation. Above that, it is likely to carry clinical implications on questions of postinterventional management such as oral anticoagulation.

Figure 19.3. Diagram showing the postinterventional follow-up after AF ablation using transtelephonic ECG monitoring every other day. The time to the first AF relapse is illustrated on a Kaplan-Meier survival analysis. Plot B represents the analysis including all documented AF recurrences. Plot A represents the analysis including only symptomatic AF recurrences and thereby simulating a symptom-only-based follow-up. A: Without any blanking period. B: A blanking period of 1 month was introduced.C: The blanking period was extended to 3 months. The long-term outcome did change between the 1-month and 3-month blanking, suggesting that all patients with AF recurrences after the first postinterventional month continued to have AF recurrences. (Modified from Piorkowski C, Kottkamp H, Tanner H, et al. Value of different follow-up strategies to assess the efficacy of circumferential pulmonary vein ablation for the curative treatment of atrial fibrillation. J Cardiovasc Electrophysiol. 2005;16: 1286-1292.)

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