Efficacy of atrial substrate modification based on dominant frequency of paroxysmal atrial fibrillation

Long-Term Clinical Comparison of Procedural End Points After Pulmonary Vein Isolation in Paroxysmal Atrial Fibrillation: Elimination of Nonpulmonary Vein Triggers Versus Noninducibility

BACKGROUND

Pulmonary vein isolation (PVI) is effective for maintenance of sinus rhythm in 50% to 75% of patients with paroxysmal atrial fibrillation, and it is not uncommon for patients to require additional ablation after PVI. We prospectively evaluated the relative effectiveness of 2 post-PVI ablation strategies in paroxysmal atrial fibrillation.

METHODS AND RESULTS

A total of 500 patients (mean age, 55.7±11.0 years; 74.6% male) were randomly assigned to undergo ablation by 2 different strategies after PVI: (1) elimination of non-PV triggers (group A, n=250) or (2) stepwise substrate modification including complex fractionated atrial electrogram or linear ablation until noninducibility of atrial tachyarrhythmia was achieved (group B, n=250). During a median follow-up of 26.0 months, 75 (32.2%) patients experienced at least 1 episode of recurrent atrial tachyarrhythmia after the single procedure in group A compared with 105 (43.8%) patients in group B (P value in log-rank test of Kaplan-Meier analysis: 0.012). Competing risk analysis showed that the cumulative incidence of atrial tachycardia was significantly higher in group B compared with group A (P=0.007). With the exception of total ablation time, there were no significant differences in fluoroscopic time or procedure-related complications between the 2 groups.

CONCLUSIONS

Elimination of triggers as an end point of ablation in patients with paroxysmal atrial fibrillation decreased long-term recurrence of atrial tachyarrhythmia compared with a noninducibility approach achieved by additional empirical ablation. The post-PVI trigger test is thus a better end point of ablation for paroxysmal atrial fibrillation.

Biomarkers Associated with Atrial Fibrosis and Remodeling

Atrial fibrillation is the most common rhythm disturbance encountered in clinical practice. Although often considered as solely arrhythmic in nature, current evidence has established that atrial myopathy constitutes both the substrate and the outcome of atrial fibrillation, thus initiating a vicious, self-perpetuating cycle. This myopathy is triggered by stress-induced (including pressure/volume overload, inflammation, oxidative stress) responses of atrial tissue, which in the long term become maladaptive, and combine elements of both structural, especially fibrosis, and electrical remodeling, with contemporary approaches yielding potentially useful biomarkers of these processes. Biomarker value becomes greater given the fact that they can both predict atrial fibrillation occurrence and treatment outcome. This mini-review will focus on the biomarkers of atrial remodeling (both electrical and structural) and fibrosis that have been validated in human studies, including biochemical, histological and imaging approaches.