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This study aimed to verify the reliability of ablation index (AI) for ablation lesion estimating with different settings for radiofrequency (RF) parameters: power, impedance, contact angles, irrigation rate, temperature of irrigation saline, and irrigation solution. RF ablations (N = 66) were performed on ex vivo porcine left ventricle submerged in 37 °C saline. The aforementioned ablation parameters were changed to measure whether the size of the ablation lesion was consistent at a fixed AI value of 500. The maximum lesion diameter (r = − 0.631, P = 0.028), depth (r = − 0.896, P < 0.001), and volume (r = − 0.745, P < 0.005) were significantly reduced with an increase of the impedance. The lesion depth (P < 0.05) and the lesion volume (P < 0.05) were significantly larger with glucose irrigation than saline irrigation. In conclusion, at a fixed AI value, impedance and irrigation solution have impact on the ablation lesions, which could affect the accuracy of AI formula to estimate ablation lesion size. [ABSTRACT FROM AUTHOR]

Background: Impact of body mass index (BMI) on all-cause mortality in atrial fibrillation (AF) patients remains controversial. Methods: A total of 10,942 AF patients were prospectively enrolled and categorized into four BMI groups: underweight (BMI < 18.5 kg/m2), normal weight (BMI 18.5–24 kg/m2), overweight (BMI 24–28 kg/m2) and obesity (BMI ≥ 28 kg/m2). The primary outcome was all-cause mortality. Different Cox proportional hazards models were performed to evaluate the association between BMI and all-cause mortality. Results: During a median follow-up of 30 months (IQR 18–48 months), 862 deaths events occurred. Compared to normal BMI, higher BMI was associated with a lower mortality risk (overweight: HR 0.70; 95% CI 0.61–0.81, P < 0.0001 and obesity: HR 0.54; 95% CI 0.44–0.67, P < 0.0001) and lower BMI was associated with a higher mortality risk (HR 2.23, 95% CI 1.67–2.97, P < 0.0001). Conclusion: A reversed relationship between BMI and all-cause mortality in AF patients was found. Higher risk of mortality was observed in underweight patients compared to patients with a normal BMI, while overweight and obese patients had a lower risk of all-cause mortality. Clinical trial registration: URL: http://www.chictr.org.cn/showproj.aspx?proj=5831. Unique identifier: ChiCTR-OCH-13003729. [ABSTRACT FROM AUTHOR]

Purpose: Thyroid dysfunction affects the outcomes of atrial fibrillation (AF) catheter ablation. However, it remains unclear if the variations in thyroid function, especially in the triiodothyronine levels, are associated with AF recurrence in euthyroid subjects. This study investigated the associations of thyroid hormone levels with arrhythmia recurrence after AF catheter ablation in euthyroid patients.Methods: A total of 1115 consecutive AF patients who underwent catheter ablation were prospectively enrolled and had their thyroid function measured prior to the procedure. The serum free triiodothyronine (FT3), free tetraiodothyronine (FT4), and thyroid-stimulating hormone (TSH) levels were assessed as predictors of recurrence and were adjusted for potential confounders. The subjects were divided into five quintile groups according to the FT3, FT4, and TSH levels, respectively.Results: After a median follow-up of 723 days (interquartile range, 180-1070), 47.2% of patients experienced recurrence. After multivariate adjustment, subject in the lowest and highest FT3 quintiles showed increased risk of recurrence (hazard ratio [HR] 1.60, 95% confidence interval [CI] 1.26-2.03, P < 0.01, and HR 1.47, 95% CI 1.16-1.87, P < 0.01, respectively), compared to the median quintile of FT3 levels. Regarding the FT4 level, the highest quintile group showed a higher risk of recurrence (HR 1.27, 95% CI 1.01-1.60, P = 0.04). The TSH levels were not associated with AF recurrence.Conclusions: Both high and low FT3 levels were associated with AF recurrence after catheter ablation. High-normal FT4 levels were also related to AF recurrence; however, no association was found between normal TSH levels and AF recurrence. [ABSTRACT FROM AUTHOR]