Recently, there has been a great deal of interest in the mechanistic role of inflammation in the initiation, maintenance, and perpetuation of atrial fibrillation (AF).1,2 Several studies have focused on inflammatory biomarkers and acute-phase proteins to further understand the inflammatory milieu in relation to AF. These studies have demonstrated that both interleukin-6 (IL-6) and C-reactive protein (CRP) are elevated in paroxysmal and persistent AF.3,4,5 Chung et al.4 demonstrated an association between elevated CRP levels and AF in a nonoperative setting. In this study, CRP levels were more than 2-fold higher in patients with AF than in control subjects. Moreover, patients with persistent AF had higher CRP levels than patients with paroxysmal AF, suggesting that inflammation may be more relevant to promoting AF maintenance than its initiation. Similarly, Dernellis and Panaretou 6 demonstrated CRP elevation in patients with paroxysmal AF and that CRP levels were higher in the subgroup that failed pharmacologic cardioversion with amiodarone. Lower CRP levels have been associated with successful cardioversion and maintenance of sinus rhythm. Sata et al.7 measured inflammatory markers at different time intervals pre and post cardioversion in 15 patients with paroxysmal AF and found that CRP, IL-6, and tumor necrosis factor (TNF-α) were significantly elevated when compared to controls and remained elevated for up to 2 weeks after cardioversion. Although this study was small, the authors suggested that inflammation played a role in the initiation of AF. Whether an increase in inflammatory markers is a cause or a consequence of AF, there is a clear association between the two processes and growing interest in developing therapeutic options to modulate the inflammatory state.
Early recurrence of atrial arrhythmias after pulmonary vein isolation is common and does not necessarily indicate failure of the procedure.89
Though, there is data to support that early recurrence of AF is associated with a lower long-term success rate.10,11 It is not clear how to manage patients with early recurrence after AF ablation and thus, there is uniform interest in developing treatment strategies to deal with this subset of patients, including reablation and/or medications. A recent consensus document on catheter and surgical ablation of AF12 suggested a blanking bperiod of at least three months in regards to repeat ablation. The document did state that symptomatic, atrial arrhythmias after ablation are difficult to treat with medications and patients are best managed with repeat ablation. Lellouche et al.13 looked at an early reablation strategy to deal with early recurrences after AF ablation. The authors found that an early reablation strategy had a lower rate of clinical recurrences, but an overall higher number of ablation procedures compared with patients without an early second ablation, suggesting that the optimal timing for the second procedure remains to be defined.
It is unclear if inflammation plays a role in contributing to the early recurrence of atrial arrhythmias after ablation or if these arrhythmias are secondary to recovery of conduction in a previously isolated PV, incomplete PV isolation, or non-PV arrhythmogenic foci and therefore, a marker of late recurrence. An interesting paper by Koyama et al.14 in the American Journal of Cardiology entitled “Comparison of Characteristics and Significance of Immediate Versus Early Versus No Recurrence of Atrial Fibrillation After Catheter Ablation” sheds light on this topic. The objective of this study was to clarify the relationship between the inflammatory processes related to catheter ablation and recurrence of AF after ablation and to characterize AF recurring within three days after ablation (immediate-AF-recurrence). In this study, 186 patients with symptomatic, paroxysmal AF, who were refractory to medications, underwent extensive pulmonary vein isolation by a double lasso technique. The end point of ablation was bidirectional, pulmonary vein block and no AF induction lasting > 3min with decremental burst pacing from the coronary sinus to a cycle-length of 180ms on isoproterenol. Specific attention was paid to symptoms, physical findings, and data relative to an inflammatory response within the first three days after ablation. The variables measured included body temperature (BT) and C-reactive Protein (CRP). During the first three days after ablation, patients were monitored for pericarditis, which was confirmed by ECG diagnosis and echocardiography, and any evidence of frequent atrial premature contractions or nonsustained AF. Successful ablation was defined as the absence of AF on no antiarrhythmic drugs (AAD) after a six-month follow-up period.
Patients were divided into immediate-AF-recurrence (within 3 days), early-AF- recurrence (4-30 days) and no AF recurrence groups following ablation. During the initial one-month follow-up period, 45 patients (24%) were in the immediate-AF-recurrence group, 27 patients (14%) were in the early- AF-recurrence group, and 114 patients (61%) were in the no AF recurrence group. In the first 3 days after the ablation procedure, the immediate-AF-recurrence group had the highest body temperature, greatest change in body temperature, highest CRP level, and greatest change in CRP level from baseline compared to the early-recurrence and no recurrence groups. Nonsustained AF and frequent atrial premature contractions were more prevalent in the early-AF-recurrence group compared to the immediate- AF-recurrence and no AF recurrence groups. It is important to note that recurrent AF episodes in the immediate-AF-recurrence group were decreased at the 1 and 6 month follow-up visit. In the immediate-AF-recurrence, 45 patients had recurrent AF in the first three days post ablation, which decreased to 10/45 patients and 11/45 patients at 1 and 6 months of follow-up respectively. In contrast, the prevalence of AF recurrence was > 70% at 1 and 6 months in the early-AF-recurrence group.
In this study, the AF-free rate after 6 months of follow- up was greater in the immediate-AF-recurrence group (76%) than in the early-AF-recurrence group (30%). The authors concluded that immediate- AF-recurrence was associated with an acute inflammatory response after ablation with a high BT, increased CRP levels, and signs and symptoms of pericarditis. In most cases, AF recurrence in the immediate-AF-recurrence group resolved spontaneously within 1 month and AF freedom persisted at 6 months, indicating that immediate- AF-recurrence may have a different mechanism than early-AF-recurrence. In contrast, an early- AF-recurrence (4-30 days) was the most powerful predictor of AF recurrence at the end of the 6 month follow-up period and suggested a different mechanism for AF recurrence: recovery of conduction between the pulmonary veins and the left atrium or the presence of non-pulmonary vein foci.
This study introduces an interesting concept: AF recurrence in the setting of an acute inflammatory response. The majority of patients in the immediate- AF-recurrence group did well at the 6-month follow-up and did not require repeat ablation. Thus, it would have been wrong to assume failure in this select group and from this study, it is apparent that immediate-AF-recurrence had different characteristics than early-AF-recurrence. Ricther et al.15 recently published a study on the prognostic value of early AF recurrence within 48 hours after ablation and its impact on long-term outcome. This study included both paroxysmal and persistent patients using two, different ablation strategies and pulmonary vein entrance block as the endpoint of ablation. Although the authors found that early recurrence of AF within 48 hours after ablation was a significant predictor of a poor long-term ablation outcome, they noted that 46% of patients with early AF recurrence were AF free during long-term follow-up. These two studies support the concept of an acute inflammatory process at work, which may confer a benefit in the overall outcome as the healing process occurs.
Richter et al. also looked at the use of statins, angiotensin- converting enzyme inhibitors, and angiotensin II receptor blockers in relation to ablation outcome and found that none of these medications resulted in an improved ablation outcome.16 Roux et al. recently studied the use of antiarrhythmics after ablation of atrial fibrillation (5A Study).17 This study randomized patients with paroxysmal AF undergoing ablation to empiric versus no antiarrhythmic drug (AAD) therapy for the first six weeks after ablation and found that AAD therapy reduced the incidence of clinically significant atrial arrhythmias and need for cardioversion.
In summary, the concept of an acute inflammatory response in relation to early recurrence supports an extended blanking period after the initial ablation procedure. The data from Koyama et al.14 suggest that immediate recurrence of AF after ablation may be related to an inflammatory response and that conservative treatment in this group, until the inflammatory state subsides, is prudent. AAD therapy after ablation should be encouraged in the group with immediate recurrence of AF in the short-term. While conservative treatment is also reasonable for patients with early AF recurrence, one should be vigilant for late AF recurrence in this subgroup of patients and have a low threshold for repeat ablation if AF persists. Additional prospective clinical trials utilizing anti-inflammatory treatment after ablation seems warranted to determine if modification of the inflammatory state will diminish early AF recurrences after ablation.