Progression and regression in the left atrial substrate in patients with atrial fibrillation: the PROGRESS-AF study

FUNDING ACKNOWLEDGEMENTS: Type of funding sources: None. BACKGROUND: Progression or regression of the atrial substrate in atrial fibrillation (AF) has been demonstrated in animal models and human right atrial maps. Dynamic changes over time of the left atrial (LA) substrate in patients with AF have not been evaluated in detail yet. PURPOSE: To evaluate changes of the LA substrate between first and redo AF ablation procedures. METHODS: In our prospective single center observational study, consecutive patients undergoing first and redo AF ablation during sinus rhythm were included. The LA was divided into anterior, septal, lateral and inferior regions. The veins and posterior segments were excluded from the analysis. In each segment median voltages and area % of spontaneous low voltage zone (LVZ) of the LA (<0.5 mV) were measured and compared between first and second procedure in each patient. Progression/Regression was diagnosed if a significant concordant decrease/increase in the median voltage in at least two regions was observed, respectively. RESULTS: In the first procedure 34.055 (1.216 points/patient) and in the second 76.958 (2.748 points/patient) points were analyzed in 28 patients (age: 61.2±9.5 years, 39% female, 39% persistent AF). The time between first and second procedure was 1.2 (0.4-2.3) years. Eleven (39%) patients had spontaneous >5% LVZ at both first and second procedure (p=1). In 17 (60%) patients progression was identified; in 5 patients in all 4 segments, in 8 in 3 and in 4 in 2. In the Progression group the total mean LA voltage (1.28±1.30 vs. 0.76±0.71 mV, p<0.001) and the regional mean voltage in all atrial regions decreased significantly: anterior: 0.80±0.76 vs. 0.52±0.51, p<0.001; septal: 1.04±0.94 vs. 0.68±0.57,p<0.001; lateral: 1.71±1.60 vs. 1.04±1.01, p<0.001; and inferior 1.69±1.58 vs. 0.80±0.62, p<0.001. The % LVZ increased not significantly: 6.3±9.5% vs. 9.8±10.1%, p=0.3. In 11 (40%) patients regression was observed (in 3 patients in 3 regions and in 8 in 2). In the Regression group the total mean LA voltage (1.47±1.35 vs. 1.89±1.56, p<0.001) and the regional mean voltage in all but one atrial regions increased significantly: anterior: 1.60±1.55 vs. 1.84±1.58, p=0.001; lateral: 1.59±1.26 vs. 2.59±1.81, p<0.001; inferior: 1.29±1.10 vs. 1.84±1.33, p<0.001; and septal: 1.36±1.43 vs. 1.25±1.18, p=0.06. The % LVZ decreased not significantly (8.6±9.5% vs. 4.1±10.1%, p=0.1). There was no significant difference in any baseline clinical or echocardiographic parameter between the Progression and Regression group. CONCLUSIONS: Our preliminary study is the first to report bidirectional dynamic properties of the LA substrate with concordant either progressive or regressive changes of atrial voltage in different atrial regions outside of the PVs following AF ablation. A better understanding of the dynamic changes of the LA substrate could help to differentiate between patients with reversible and despite ablation therapy progressive irreversible atrial structural remodeling.