66Clinical outcomes after catheter ablation for atrial fibrillation in elderly patients: a French nationwide cohort study

Methods

This French longitudinal cohort study was based on the national hospitalization PMSI (Programme de Médicalisation des Systèmes d'Information) database covering hospital care from the entire population. We included all patients, over 18 years old, with AF from January 2010 to December 2015.

Results

Among the 1,663,284 patients identified with AF, 28,018 patients were treated with AF ablation (28% female, mean age 60±10 yo) and 1,635,266 did not have AF ablation (48% female, mean age 78±11 yo). Among those treated with AF ablation, 1,605/28,018 patients (5.7%) were aged >75 yo.

During follow-up (456±546 days), hospitalization with a primary diagnosis of HF and death were recorded. Incidences of hospitalization for HF and death were significantly lower in AF ablation group (respectively 6.09% vs 13.29% person per year, p<0.0001, and 1.49% vs 17.11% person per year, p<0.0001). These associations were confirmed in a multivariable analysis after adjustment on age and other comorbidities (HR 0.66, 95% CI 0.63–0.69, p<0.0001 for HF and HR 0.21, 95% CI 0.19–0.23, p<0.0001 for all-cause death). Results were significant and relatively similar whether patients were aged below or above 75 yo: HR 0.63, 95% CI 0.60–0.66, p<0.0001 when age <75 yo and HR 0.60, 95% CI 0.51–0.70, p<0.0001 when age >75 yo for hospitalization for HF; HR 0.21, 95% CI 0.19–0.24, p<0.0001 when age <75 yo and HR 0.36, 95% CI 0.29–0.45, p<0.0001 when age >75 yo for all-cause death.

Conclusion

In the nationwide analysis of unselected AF patients seen in hospitals, AF ablation was independently associated with a lower risk of hospitalization for HF and death whether patients were aged below or above 75 yo.

P6576Use of atrioventricular nodal ablation after atrial fibrillation ablation failure: a nationwide cohort study

Methods

This French longitudinal cohort study was based on the national hospitalization database covering hospital care from the entire population. The data for all patients admitted in France from January 2010 to December 2015 were collected from the national administrative database, the PMSI (Programme de Médicalisation des Systèmes d'Information). We included all patients, over 18 years old, with AF and at least one AF catheter ablation. Routinely collected medical information includes the principal or secondary diagnoses and procedures performed. Items from the baselines characteristics were pooled into a multivariate Cox model to identify predictors of AV node ablation.

Results

Of 1,663,284 patients identified with AF, 28,018 patients were treated with AF ablation (28% female, mean age 60±10 yo, 22,837 with 1 procedure, 4,576 with 2 procedures and 605 with 3 procedures). Of those 28,018 patients, there were only 369 patients (1.3%) treated with AVNA after a mean follow-up of 374±488 days (median 210, interquartile 15–798). AVNA was less commonly performed than redo AF ablation with 3 procedures, and among these latter patients, only 3.8% were treated with AVNA during follow-up. Most powerful independent predictors of AV node ablation (HR >1.7) were age≥75 yo, heart failure at baseline, abnormal renal function and valve disease. Other independent predictors for AV node ablation (HR 1.2–1.7) were age 65–74 yo, female gender, obesity, coronary artery disease, thyroid disorders, lung disease and hypertension.

Conclusion

Our findings indicate that AVNA is rarely used after AF ablation failure and is probably an underrated strategy in these patients for now. Considering evidence from the APAF-CRT trial indicating a beneficial effect on mortality of this treatment in symptomatic AF patients, a wider use of AVNA should be more widely proposed in these patients. Its optimal timing during rate and rhythm control management still remains to be established.

P4748HASBLED score, frailty index or comorbidity index for bleeding risk assessment in patients with atrial fibrillation?

Background

Charlson comorbidity index (CCI) is a tool to measure comorbid disease status and a strong estimator of mortality. The quantifiable frailty phenotype has also been validated as predictive of mortality and disability. Claims data can be used to classify individuals as frail and non-frail using the Claims-based Frailty Index (CFI). We evaluated whether these tools may help to predict the risk of bleeding in patients with atrial fibrillation (AF).

Methods

All patients with AF seen in an academic institution were identified and followed up for mortality, stroke and bleeding events. HAS-BLED, HEMORR2HAGES, ATRIA and ORBIT scores, CCI and CFI were calculated for each patient. Hazard ratios were calculated and predictive abilities of the scores were compared using the c-statistic in the whole population and then separately in elderly patients (>75 yo).

Results

Among 8962 patients with AF, 274 major bleeding events were recorded during a follow-up of 874±1054 days. Bleeding occurred more commonly in patients with higher bleeding risk scores, CCI and CFI. The 4 bleeding risk scores significantly had lower c-statistics than CCI and CFI for predicting major bleeding (table). Results were similar whether patients were treated with OAC or no OAC. In elderly patients, the c-statistics were all lower and were not significantly different for the 4 scores, CCI and CFI scores (0.594, 0,572, 0.595, 0.594, 0.616 and 0.591 for HAS-BLED, HEMORR2HAGES, ATRIA, ORBIT, CCI and CFI, respectively).

Predictive values for major bleeding ROC Area 95% Conf. Interval P value vs CCI/CFI HASBLED 0.588 0.555–0.621 0.002/0.003 HEMORR2HAGES 0.564 0.531–0.598 <0.0001/<0.0001 ATRIA 0.559 0.522–0.595 <0.0001/<0.0001 ORBIT 0.577 0.542–0.612 0.0002/0.0003 Charlson, CCI 0.652 0.619–0.684 –/0.58 Frailty index, CFI 0.648 0.615–0.681 0.58/–

Conclusion

Comorbidities and frailty, respectively assessed with CCI and CFI, demonstrated statistically better performances in predicting major bleeding than the 4 established bleeding risk scores in AF, although all c-indexes were broadly similar. The 4 bleeding risk scores, CCI and CFI showed lower performance in predicting bleeding within elderly patients in whom they all performed equally to predict bleeding events. Given their simplicity and similar performances, the user-friendly bleeding risk scores remain attractive tools for the estimation of bleeding risk in elderly patients with AF.

Stabilization of Bacillus circulans xylanase by combinatorial insertional fusion to a thermophilic host protein

High thermostability of an enzyme is critical for its industrial application. While many engineering approaches such as mutagenesis have enhanced enzyme thermostability, they often suffer from reduced enzymatic activity. A thermally stabilized enzyme with unchanged amino acids is preferable for subsequent functional evolution necessary to address other important industrial needs. In the research presented here, we applied insertional fusion to a thermophilic maltodextrin-binding protein from Pyrococcus furiosus (PfMBP) in order to improve the thermal stability of Bacillus circulans xylanase (BCX). Specifically, we used an engineered transposon to construct a combinatorial library of randomly inserted BCX into PfMBP. The library was then subjected to functional screening to identify successful PfMBP-BCX insertion complexes, PfMBP-BCX161 and PfMBP-BCX165, displaying substantially improved kinetic stability at elevated temperatures compared to unfused BCX and other controls. Results from subsequent characterizations were consistent with the view that lowered aggregation of BCX and reduced conformational flexibility at the termini was responsible for increased thermal stability. Our stabilizing approach neither sacrificed xylanase activity nor required changes in the BCX amino acid sequence. Overall, the current study demonstrated the benefit of combinatorial insertional fusion to PfMBP as a systematic tool for the creation of enzymatically active and thermostable BCX variants.