Catheter Ablation
B-Type Natriuretic Peptide Level for Atrial Fibrillation Ablation ― Is It a Wonderful Fortune Teller or a Mirror Reflecting Reality? ―
2023 Volume 87 Issue 12 Pages 1740-1741
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2023 Volume 87 Issue 12 Pages 1740-1741
Heart failure (HF) is one of the major causes of death in atrial fibrillation (AF) patients,1,2 and the management of HF occurrence is a crucial challenge in the care of AF patients, together with stroke prevention. Catheter ablation has gained attention as one of the treatment options for AF complicating HF, particularly after the results of the CASTLE-AF trial.3 On the other hand, catheter ablation is an invasive procedure, not without complications itself, and as a result, there are certain limitations to its treatment outcomes. Recurrence is a significant issue for this procedure. Therefore, the ability to predict recurrence before commencing the procedure is of utmost importance in making an informed decision. Many factors have been reported to predict recurrence after ablation, but there is a limited number of indicators with high-level evidence.4 The B-type natriuretic peptide (BNP) levels before and after ablation have long been reported as useful for predicting recurrence and the onset of HF events after ablation.5–11 However, there is ongoing debate about whether they simply reflect the current rhythm and heart rate,12 raising the old question: “Is it a wonderful fortune teller or a mirror reflecting reality?”
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Amidst the diverse range of reports, the paper by Kawaji et al13 in this issue of the Journal, involving a substantial cohort of 1,750 patients, provides a comprehensive scrutiny down to the minutiae and offers fresh insights into the significance of BNP in predicting post-ablation events. First, they show that the significance of baseline BNP as a predictor of post-ablation adverse events, as previously identified in small-scale studies, has been confirmed in a large-scale cohort study of Japanese individuals. Second, that the baseline BNP level was significantly associated with the development of HF after ablation, but its predictive value for atrial arrhythmias, persistent AF in particular, is limited. On the other hand, under the condition that “the cumulative incidence of recurrent atrial tachyarrhythmias after the procedure was 27.9% at 3 years”, the BNP levels at 3 months post-ablation had significantly decreased in all subgroups. They also show that a low follow-up BNP level was independently associated with lower risk for arrhythmia recurrence, but not with the lower composite HF endpoint, though it had some effect before adjusting the confounder and a value >108 pg/mL seemed to be related to the higher composite HF endpoint according to their figure 3. By reaffirming the association of BNP with adverse events in ablation patients, this study has undoubtedly provided valuable insights, particularly in the context of the primary target population of this research: non-HF patients. Therefore, it is likely to be a useful reference in determining the suitability of AF ablation. Based on these results, it now appears that we may be able to consider the BNP level not just as a mirror reflecting reality, but as a fortune teller predicting the future.
However, there are still several unresolved issues when it comes to evaluating BNP levels. For example, as authors comment on the variability of baseline BNP levels depending on patient background, making it difficult to determine the best cutoff using receiver operating characteristic curves. In the RAFT-AF study,14 targeting HF patients, the NT-proBNP level in the Ablation-based Rhythm Control group was considerably high at 1,689 pg/mL (BNP≒260~280 pg/mL) compared with the results given by Kawaji et al.13 Furthermore, the question arises: Is baseline BNP the most critical factor, or is it the post-procedure BNP level and its rate of reduction, as also commented on Kawaji et al.13 The timing of BNP measurement is an issue. In the RAFT-AF study,14 the NT-pro BNP level had decreased by an average of 80% at 12 months after ablation and had decreased 45% in the Rate Control group. Although the reduction was significantly greater in the Ablation-based Rhythm Control group, there was no statistical difference in all-cause death or HF events with ablation-based rhythm-control vs. rate-control in that study.14 Therefore, it is considered that studies of BNP levels tailored to specific diseases and clinical backgrounds will be necessary in the future. Finally, an unresolved issue is how far into the future can the BNP level provide insights. In a meta-analysis that examined the predictive value of BNP for recurrence, it was found to be linked to the follow-up period, with baseline BNP particularly associated with early post-ablation recurrence,7 which raises intriguing questions about the underlying mechanisms between BNP and AF occurence. The follow-up period in the study by Kawaji et al13 was similar to that of some previous studies investigating late recurrence, but addressing the challenge of long-term follow-up, extending beyond 5 years, is an issue that still needs to be resolved, and future research is eagerly anticipated.
The author declares no conflicts of interest associated with this manuscript.
Name of the ethics committee, N/A; Reference number, N/A.
