Abstract
BACKGROUND AND AIMS: Arrhythmia recurrence after a good durable circumferential pulmonary vein isolation (CPVI) was a noteworthy issue in patients without significant low voltage area (LVA) at 0.5mV threshold. In this context, areas manifesting bipolar voltage between 0.5 and 1.0mV might serve as the transition zones that foresee further fibrosis or voltage decrease in the future. In the current study, we sought to determine the predictive value of transition zones for arrhythmia recurrence after CPVI in patients with absence or mild LVA (less than 5%) and pinpoint the predictors for recurrence at different follow-up (FU) period. METHOD: The inclusion criteria were presence of LVA (below 0.5 mV bipolar threshold) less than 5% of left atrium (LA) during high-density mapping (>2000 mapped sites per LA) in SR. A total of 213 patients (66 female and 147 male, 53.1% paroxysmal AF) were enrolled, electroanatomical parameters including left atrial volume (LAV), LVA in SR at both 0.5-and 1.0 bipolar thresholds were obtained. The extent of transition zone (area percentage in LA between 0.5 and 1.0 mV) were defined as the result of LVA percentage in LA at 1.0mV subtracting LVA at 0.5mV. After CPVI was achieved, all patients completed rhythm FU visits with 72-hour Holter recordings at 3, 6, 12, 24, 36, 48 and 60 months. RESULTS: The multivariate COX regression identified that LAV was the only significant predictor (HR: 1.02 (1-1.03), p=0.012) for arrhythmia recurrence within 12-month FU,whereas arrhythmia recurrence was significantly related to transition zone percentage (HR: 1.03 (1.01-1.05), p=0.017) after 12-month FU. ROC curves indicated that LAV had higher AUC at 12-month FU than transition zone percentage (0.658 vs. 0.632), while transition percentage maintained higher AUC value over 0.60 than LAV after 12-month. The cutoff thresholds of LAV and transition zone percentage were determined based on ROC curves at different FU period. As a result, LAV at 123ml was significantly predictive (p=0.002) for arrhythmia recurrence within 12-month FU and the thresholds of 100ml was a strong predictor (p<0.001) after 36-month FU. The transition zone percentage, on the other hand, did not demonstrate significantly predictive value within 12-month (Cutoff 15%, p=0.255) but displayed promising predictive power after 12-month (5% at 24-month, HR 1.93, p=0.006; 2.8% after 36-month, HR2.21, p<0.001). CONCLUSIONS: In AF patients with absence or mild LVA (less than 5%) at bipolar 0.5 mV that underwent CPVI, the transition zone signifies an area that are at risk to develop fibrosis and induce arrhythmia recurrence in the future, hence as a warning signal. However, the prognostic effect of transition zone was more profound after 12-month, thus predicting long-term recurrence whereas the enlarged LA was more predictive for recurrence within 12-month. Awareness should be raised to properly evaluate the extent of low voltage substrate as well as the transition zone. [Figure: see text] [Figure: see text]