Purpose To evaluate the proportion of patients in whom parameters that define the diagnosis of HFpEF and HFmrEF persist versus normalize upon elimination of AF. Background Atrial fibrillation (AF) and heart failure with preserved or mid-range ejection fraction (HFpEF or HFmrEF) concur in many patients. Distinction between these two diagnoses remains challenging as one can cause or exacerbate the other. Adequate patient selection for invasive AF treatment is crucial to improve rhythm outcome. Methods Patients underwent thoracoscopic ablation, consisting of pulmonary vein isolation (PVI) alone or PVI with additional lines in the case of persistent AF. Patients were prospectively followed-up. HFmrEF or HFpEF was defined as left ventricular ejection fraction (LVEF) ≥40% or ≥50% respectively and N-terminal prohormone of brain natriuretic peptide (NT-proBNP) levels >125 pg/ml. Patients who remained free from AF, or any atrial tachycardia of more than 30 seconds, at 6 months postoperatively, were included in this study. Patients with AF recurrences during this period were excluded. The primary outcome was the change of NT-proBNP at 6 month follow-up. Results From 2008 to 2017, 92 patients undergoing thoracoscopic AF ablation fulfilled the aforementioned criteria and were included. Of these patients, mean age was 61±8 years and 66 (72%) were male. Median NT-proBNP was 366 pg/ml (128–2916) and mean LVEF was 53±7%. Thirty (35%) patients had a LVEF of 40–49%. Six months after elimination of AF, NT-proBNP was <125 pg/ml (Figure 1A: median 87 (50–122) vs 459 (137 – 2916) pg/ml at baseline; p<0.001) in 26 patients (28%), whereas in the remaining patients NT-proBNP was unchanged (Figure 1B: median 298 (126–1568) vs. 318 (128–2387) pg/ml at baseline; p=0.011). Figure 1. NT-proBNP alterations after thoracoscopic AF ablation from baseline to 6 month follow-up. A. Patients with normalization of NT-proBNP. B. Patients with unchanged high levels of NT-proBNP. Conclusion In 28% of patients the diagnostic criteria of HFpEF/HFmrEF are caused by AF and normalize upon elimination of AF with thoracoscopic ablation.

BackgroundMucosal associated invariant T (MAIT) cells are innate-like T-cells involved in the antibacterial and fungal response by recognizing riboflavin metabolites produced by these organisms. MAIT cells are present in blood and are highly abundant in the mucosa of the liver, lungs and intestines. In murine models of urinary tract infection (UTI), MAIT cells appear to migrate to the bladder and decrease the bacterial load. It is however unknown whether MAIT cells reside in the human urogenital tract and renal tissue and whether they play a role in the first-line defense against (recurrent) UTI (RUTI).MethodsWe used a fluorescently labelled MR1-tetramer in conjunction with 14-color flowcytometry to identify and characterize MAIT cells in renal allografts after allograft failure caused by RUTI (n = 6) or rejection (n = 6) and in healthy kidney tissue surgically removed because of renal cell carcinoma (adjacent nontumorous tissue) (n = 5).ResultsThe mean percentage of MAIT cells within the lymphogate was higher in the RUTI kidneys (2.24%) compared with the rejection kidneys (0.14%) and the control kidneys (0.11%) (P < 0.05).Characterization of MAIT cells was impossible in some control samples due to MAIT cells counts <25 (predefined cutoff value), therefore the control group was excluded from further statistical analysis.MAIT cells in RUTI kidneys appear to have a less activated profile compared with the rejection kidneys, with a lower expression of Ki67 (P < 0.01). Though the expression of the tissue resident marker CD69/CD103 was higher in 4/6 RUTI kidneys, this difference was not significant.ConclusionMAIT cells are present in renal tissue that is or has been subjected to an immunologic response. MAIT cells in RUTI kidneys display a more quiescent and in some samples more tissue resident phenotype than MAIT cells in rejection kidneys. These findings may suggest that (I) MAIT cells play a role in the first-line defense in the kidney and (II) that after RUTI, MAIT cells remain in renal tissue in a quiescent state. We postulate that this might be favorable in case of a second hit from an uropathogen.Figure 1.Presence and characterization of MAIT cells in renal tissue.Disclosures F. Bemelman, Astellas: We received an unrestricted grant from Astellas to establish a Biobank for patients with renal diseases. The samples described in this abstract are obtained from this Biobank., Grant recipient.

Background Severely enlarged left atrial (LA) volume is associated with a considerable ineffective outcome of ablation for atrial fibrillation (AF). Therefore, in patients with AF and a giant atrial volume catheter ablation is not recommended. However, thoracoscopic AF ablation is being performed in patients with AF and giant LA, but with unknown efficacy. Purpose To determine efficacy of thoracoscopic AF ablation in patients with AF and a giant LA. Methods Patients underwent thoracoscopic AF ablation (paroxysmal AF) plus additional left atrial ablations (persistent AF) and were prospectively followed. Giant LA was defined as left atrial volume index (LAVI)≥50 ml/m2, outcome was also assessed for LAVI≥55 ml/m2. Follow-up was performed with ECGs and 24-hour Holters every three months. After a 3-month blanking period, all AADs were discontinued. Primary outcome was recurrence of any atrial tachycardia ≥30 sec during one year of follow-up. Results Between 2008–2017, 357 patients underwent thoracoscopic AF ablation. At baseline, giant LA was diagnosed in 72 (20.2%) patients (mean LAVI: 59.5±9.6 ml/m2), while 285 (79.8%) had a smaller left atrium (mean LAVI: 36.3±7.8 ml/m2), p<0.001. Giant LA patients were older (mean: 61.7±6.9 vs 59.3±9.0 years, p=0.03) and more often diagnosed with persistent AF (n=60, 83.3%) compared to control (n=164, 57.5%), p<0.001. Sex (female: n=19, 26.4% vs n=79, 27.7%, p=0.82) and history of AF (median: 4.0 [IQR: 2.0–6.0] vs 4.0 [IQR: 2.0–8.0] years, p=0.10) were equally distributed. Freedom of any atrial tachycardia did not differ significantly between both groups (n=43, 59.7% vs n=195, 68.4%, log rank p=0.91), figure. This was similar for the cut-off of LAVI≥55 ml/m2: n=24/43 (55.8%) vs n=214/314 (68.2%), p=0.15). AF recurred in 16 (22.2%) patients with giant LA compared to 55 (19.3%) patients, while atrial tachycardia recurred in 21 (29.2%) vs 56 (19.6%) patients, respectively, p=0.06. Kaplan-Meier analysis of AF recurrence i Conclusion Thoracoscopic AF ablation is an effective therapy in patients with a giant LA. Thoracoscopic AF ablation may therefore be a feasible treatment for patients with a giant LA.

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