The percentage of asymptomatic Chagas' patients who had a specific AAB pattern and had a beta1-AAB level above a defined cutoff point mirrors very well the epidemiological situation, which showed that clinical manifestations develop in nearly 30% of Chagas' patients and cardiomyopathy in nearly 90% of them. We hypothesize that beta1-, beta2-, and M2-AAB measurement might be a useful tool for risk assessment in the indeterminate state of Chagas' disease to select patients for earlier involvement in care programs. However, prospective studies are needed to further evaluate this hypothesis.

Aims While the CLOSE protocol proposes a maximally tolerable interlesion distance (ILD) of 6 mm for ablation index ablation index-guided atrial fibrillation (AF) ablation, a target ILD has never been defined. This randomized study sought to establish a target ILD for ablation index-guided AF ablation. Methods and results Consecutive patients scheduled for first-time pulmonary vein (PV) isolation (PVI) were randomly assigned to ablation protocols with a target ILD of 5.0–6.0 mm or 3.0–4.0 mm, with the primary endpoint of first-pass PVI. In compliance with the CLOSE protocol, the maximum tolerated ILD was 6.0 mm in both study protocols. A target ablation index of ≥550 (anterior) or ≥400 (posterior) was defined for the ‘5–6 mm’ protocol and ≥500 (anterior) or ≥350 (posterior) for the ‘3–4 mm’ protocol. The study was terminated early for superiority of the ‘3–4 mm’ protocol. Forty-two consecutive patients were randomized and 84 ipsilateral PV pairs encircled according to the study protocol. First-pass PVI was accomplished in 35.0% of the ‘5–6 mm’ group and 90.9% of the ‘3–4 mm’ group (P < 0.0001). Median ILD was 5.2 mm in the ‘5–6 mm’ group and 3.6 mm in the ‘3–4 mm’ group (P < 0.0001). In line with the distinct ablation index targets, median ablation index was lower in the ‘3–4 mm’ group (416 vs. 452, P < 0.0001). While mean procedure time was shorter in the ‘3–4 mm’ group (149 ± 27 vs. 167 ± 33min, P = 0.004), fluoroscopy times did not differ significantly (4.7 ± 2.2 vs. 5.1 ± 1.8 min, P = 0.565). Conclusion In ablation index-guided AF ablation, an ILD of 3.0–4.0 mm should be targeted rather than 5.0–6.0 mm. Moreover, the lower target ILD may allow for less extensive ablation at each given point.

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