TZ burden is correlated with slow left atrial conduction velocity and independently predicts atrial tachyarrhythmia recurrence following circumferential pulmonary vein isolation in elderly patients with paroxysmal AF without low-voltage areas.
Key Findings
Results
Higher transition zone burden was associated with significantly decreased anterior left atrial conduction velocity in a dose-dependent fashion across the three TZ burden groups.
Anterior LACV decreased progressively: 1.52 ± 0.36 m/s in TZ < 5% group, 1.21 ± 0.27 m/s in TZ 5%-15% group, and 1.02 ± 0.25 m/s in TZ > 15% group (p < 0.0001).
TZ burden groups were defined as < 5% (n = 48, 30.4%), 5%-15% (n = 66, 41.8%), and > 15% (n = 44, 27.8%).
TZs were defined as regions with bipolar voltage between 0.5 and 1 mV in more than 3 adjacent points.
TZ burden was calculated as the proportion of TZ on the entire left atrium surface.
Results
Patients who experienced atrial tachyarrhythmia recurrence had significantly higher TZ burden than those without recurrence.
Median TZ burden was 15.4 (IQR 7.2–22.4) in patients with recurrence versus 8.2 (IQR 3.5–14.3) in those without recurrence (p < 0.0001).
40 of 158 patients (25.3%) experienced recurrence over a mean follow-up of 24.9 months.
Recurrence was defined as any episode of atrial tachyarrhythmia lasting ≥ 30 seconds after a 3-month blanking period.
Results
TZ burden independently predicted atrial tachyarrhythmia recurrence after CPVI in multivariable Cox regression analysis.
Adjusted hazard ratio for TZ burden was 1.065 (95% CI 1.034–1.098, p < 0.0001) per unit increase in TZ burden.
The association remained significant after adjustment for other variables in the multivariable model.
The study enrolled 158 patients with paroxysmal AF without low-voltage areas, with mean age 69.7 ± 3.8 years.
Methods
The study population was elderly patients with paroxysmal atrial fibrillation specifically selected to exclude those with low-voltage areas.
Mean age of the 158 enrolled patients was 69.7 ± 3.8 years.
All patients underwent circumferential pulmonary vein isolation (CPVI).
Patients without low-voltage areas were specifically selected to isolate the effect of transition zone burden as a substrate.
Mean follow-up duration was 24.9 months.
What This Means
This research suggests that a type of abnormal heart tissue called 'transition zones' — areas of the left atrium with intermediate electrical voltage levels, neither fully healthy nor fully scarred — plays an important role in predicting whether atrial fibrillation (AF) will come back after a common ablation procedure called pulmonary vein isolation. The study looked specifically at elderly patients (average age around 70) whose hearts did not have the more obvious low-voltage (scarred) areas that are already known to be problematic, focusing instead on these intermediate transition zones as a distinct substrate.
The researchers found that patients with more transition zone tissue in their left atrium had slower electrical conduction through the heart, which is a known factor in sustaining abnormal heart rhythms. Over roughly two years of follow-up, about one in four patients had their arrhythmia come back, and those who did had significantly more transition zone tissue than those who remained in normal rhythm. Even after accounting for other factors, the amount of transition zone tissue was independently associated with a 6.5% higher risk of recurrence for each unit increase in TZ burden.
This research suggests that mapping and measuring transition zones before or during ablation procedures could help identify elderly AF patients who are at higher risk for recurrence even when their hearts appear relatively healthy by standard voltage criteria. This could potentially guide more personalized treatment strategies, though further research would be needed to determine whether targeting these zones during ablation would improve outcomes.
Wang Y, Qiu Y, Wang H, Cui C, Wang Z, Jiang X, et al.. (2026). Association of Transition Zone Burden With Recurrence in Elderly Patients With Paroxysmal Atrial Fibrillation Without Low-Voltage Areas.. Clinical cardiology. https://doi.org/10.1002/clc.70435