Could AF Ablation have a "Placebo" Effect?
Could AF Ablation have a "Placebo" Effect?
Pulmonary vein ablation procedures for atrial fibrillation (AF), initially thought to be a major breakthrough due to their potential for “curing” AF, have lost some momentum due to the disappointing recurrence rates of the arrhythmia. In addition, the procedure has not shown any mortality benefit or decrease in the rate of stroke or systemic embolism in randomized controlled trials. Furthermore, inappropriate use of these ablation procedures has increased scrutiny of the original indications for the procedure. At present, the main advantage of pulmonary vein ablation comes from its ability to improve patient symptoms.
A recent report in JACC: Electrophysiology provides some insight into the relief from symptoms patients experience after ablation procedures for AF. Essentially, the small study found a poor correlation between recurrence of AF and the patient’s perception of symptom relief. Only 54 patients enrolled from two Swedish centers completed the 24 month follow-up; AF symptoms were assessed at 6, 12, and 24 months following ablation using the European Heart Rhythm Association (EHRA) AF6 questionnaire. Objective recurrence of the arrhythmia was determined by an implantable loop recorder. Physicians also classified patients according to the EHRA Class (similar to NYHA Class) with respect to physician perception of impact of AF symptoms (Class I, no symptoms to Class IV, disabling symptoms). Although both AF6 scores (patient assessments) and EHRA class (physicians assessments) improved 6 months following ablation, the patient AF6 score continued to improve up to 12 months whereas physician EHRA class did not. In addition, the correlation between patients and physicians perceptions of AF symptoms was low when the AF burden was very low (≤ 0.5%) but not when the AF burden was higher. Although overall freedom from AF recurrence most often resulted in an improvement in symptoms, in some cases, patient’s reported an improvement in AF symptoms despite objective recurrence of the arrhythmia (as noted on a loop recorder).
Although overall freedom from AF recurrence most often resulted in an improvement in symptoms, in some cases, patient’s reported an improvement in AF symptoms despite objective recurrence of the arrhythmia (as noted on a loop recorder).
Although this study is very small and therefore any conclusions should be interpreted within this context, it raises many interesting questions and insights about a patient’s perception of AF symptoms after AF ablation. First, the AF6 assessment seems to be the most sensitive (although less specific) way of assessing relief from burden of AF symptoms following ablation vs EHRA class (physician’s assessment) – should this become the standardized way of assessing patient symptoms? Second, relief from AF symptoms after AF ablation is complex. In randomized trials, the endpoint of interest often used is “freedom from recurrence of arrhythmia” and this study demonstrates that symptom relief is so much more than that. Even patients who had recurrence of AF experienced symptom relief. Now, whether this is truly a “placebo” effect of the procedure or whether this is a result of partial denervation following AF (making the arrhythmia less symptomatic) is not fully understood. This will certainly need more study when one starts to think about the cost of AF ablation procedures. If it is mostly “placebo” effect, are there other more cost-effective ways of delivering this effect? Third, when determining whether AF ablation was successful, should “freedom from AF” be used as the defining endpoint or should “symptom relief” be considered the gold standard for defining the “success” of the procedure? This study further validates the currently acceptable indications for AF ablation, which include primarily symptom relief in highly symptomatic patients. As AF ablation techniques change and evolve, we will have to continue to repeat studies such as this one on a larger scale to determine whether AF ablation procedures are “successful” in relieving patient symptoms.
Björkenheim et al. Assessment of Atrial Fibrillation–Specific Symptoms Before and 2 Years After Atrial Fibrillation Ablation. JACC: Clinical Electrophysiology. Jun 2017, 405; DOI:10.1016/j.jacep.2017.04.003.