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.

Only patients with a GFR > 60 ml/min can be safely treated with enoxaparin.

Cooling effects of intrahepatic vessels could be simulated in an ex situ model. Cooling effects should be taken into account in RF ablation within 10 mm distance to major liver vessels regardless of blood flow volume or vessel diameter. Surgical RF ablation with temporary blood flow occlusion should be considered in such constellations.

Whether prepubertal estrogen production impacts on the timing of puberty is not clear. We aimed to investigate prepubertal 24-h estrogen excretion levels and their association with early and late pubertal markers. Daily urinary excretion rates of estrogens of 132 healthy children, who provided 24-h urine samples 1 and 2 yr before the start of the pubertal growth spurt [age at takeoff (ATO)], were quantified by stable isotope dilution/GC-MS. E-sum3 (estrone + estradiol + estriol) was used as a marker for potentially bioactive estrogen metabolites and E-sum5 (E-sum3 + 16-epiestriol + 16-ketoestradiol) for total estrogen production. Pubertal outcomes were ATO, age at peak height velocity (APHV), duration of pubertal growth acceleration (APHV-ATO), age at Tanner stage 2 for pubic hair (PH2), genital (G2, boys) and breast (B2, girls) development, and age at menarche. Prepubertal urinary estrogen excretions (E-sum3 and E-sum5) were not associated with ATO, APHV, and age at PH2 but with duration of pubertal growth acceleration (P < 0.01) in both sexes. Girls with higher E-sum3 reached B2 0.9 yr (P = 0.04) and menarche 0.3 yr earlier (P = 0.04) than girls with lower E-sum3. E-sum3 was not associated with age at G2 in boys (P = 0.6). For most pubertal variables, the associations with E-sum3 were stronger than with E-sum5. In conclusion, prepubertal estrogens may not be critical for the onset of the pubertal growth spurt but are correlated with its duration in both boys and girls. Prepubertal estrogen levels may already predict the timing of girls' menstruation and breast development but do not appear to affect sexual maturation in boys.