Validation of a hematology analyzer in donkey medicine

Asinina de Miranda is a protected donkey sub-species from the Mirandês plateau in northeastern of Portugal. Donkeys are animals that have substantially lost their place as working animals in modern society, this had led to a decrease in their population numbers. A need to preserve native species has led to the foundation of organizations like Associação para o Estudo e Proteção do Gado Asinino (AEPGA) and the development of studies regarding breed welfare, such as hematology. The IDEXX ProCyte Dx is a veterinary hematology analyzer validated for several species, but not for donkeys. The aim of this study was to validate the ProCyte Dx for Asinina de Miranda donkeys. The validation requires a controlled study of precision, carryover, linearity and comparison between the equipment and the manually obtained values for the leukocyte differential count and hematocrit. Results indicated coefficient of variation was good (below 5 %) for both the intra-assay and the inter-assay precision, except for basophils. Carryover was 0 % for all the parameters except platelets (5.88 %). Linearity showed a very high Pearson correlation coefficient, above 0.99, for erythrocytes, hematocrit, hemoglobin, leucocytes, neutrophils, lymphocytes, monocytes, eosinophils, platelets and plateletcrit. Comparison demonstrated excellent agreement for hematocrit (rs=0.96) and good Spearman rank correlation for neutrophils (rs=0.84) and lymphocytes (rs=0.90). Accuracy for total leukocyte count and platelets could not be determined. In conclusion, the ProCyte Dx seems appropriate to be used in Asinina de Miranda hematology.

Indexing calcium score of the aortic valve to the annulus area improves the grading of aortic stenosis severity in patients within the grey zone of aortic valve calcification

Introduction

Calcium score of the aortic valve (CaScAoV) is recommended as a supporting tool to assist in the grading of aortic stenosis (AS) severity when echocardiographic assessment is inconclusive. However, a significant proportion of patients have CaScAoV values within a “grey zone” between the “unlikely” and “likely” thresholds. The purpose of this study was to assess the potential usefulness of indexing CaScAoV to the area of the aortic annulus, in order to improve the discriminative power of CaScAoV in this subset of patients.

Methods

Consecutive patients evaluated at a single center TAVI program were retrospectively identified and included in the analysis if cardiac CT and echocardiography were performed within a 6-month timeframe. Those with LVEF <50%, indexed stroke volume <35 ml/m2, rheumatic heart disease, or bicuspid aortic valves were excluded. Severe AS was defined as mean transvalvular gradient ≥40 mmHg. The likelihood of severe AS assessed by CT was categorized according to the guideline-recommended sex-specific CaScAoV thresholds. Patients were considered to be in the “grey zone” if their CaScAoV values were between 800–1200 for women, and between 1600–2000 for men.

Results

A total of 655 patients were included (282 men (43.1%), median age 83 years [IQR 79–86]). AS was considered severe by echocardiographic criteria in 587 patients (89.6%), and moderate in the remainder. Median transvalvular gradient was 49 mmHg (IQR 43–59), and median CaScAoV values were 3329 (IQR 2356–4500) for men, and 1995 (IQR 1462–2781) for women.

Overall, 77 patients (11.7%) had CaScAoV values in the “grey zone”, of which 24 (31.2%) had moderate AS (Figure 1). Patients within this region of uncertainty were no different form the others in terms of age, sex, annulus size and body surface area.

In this subset of patients, indexing CaScAoV to aortic annulus area showed good discriminative power to identify severe AS (AUC 0.69, 95% CI 0.56–0.81, p=0.008). Using previously established thresholds (>300 AU/cm2 for women and >500 AU/cm2 for men), 48 patients (62.3%) were correctly reclassified (net reclassification index of 0.45, p=0.03). These findings were similar for both sexes.

Conclusion

In patients undergoing cardiac CT for known or suspected severe AS with CaScAoV values within the “grey zone”, indexing CaScAoV to the area of the aortic annulus improves the classification of AS severity and may decrease diagnostic uncertainty.

Funding Acknowledgement

Type of funding sources: None.

Myocardial deformation in athletes measured with feature tracking cardiovascular magnetic resonance

Background

Morphological changes of the heart associated with exercise are well studied. However, changes in myocardial mechanics of athlete's heart are less understood. The aim of this study was to analyze myocardial deformation parameters in athletes and controls, using feature tracking cardiac magnetic resonance (FT-CMR).

Methods

In a cohort of 73 athletes who had been submitted to CMR at 1.5T and 3 T (mean age 31±12 years, 69% males), we used CMR-FT to measure longitudinal, circumferential and radial strain and strain rates of both ventricles. Left ventricle (LV) longitudinal, circumferential and radial dyssynchrony index (L-SDI, C-SDI and R-CDI, respectively) was calculated as the standard deviation of the calculated time to peak strain percentages of the cardiac cycle with segmental strain analysis. We also measured these parameters in 73 age-matched healthy subjects.

Results

In comparison to the control subjects, athletes revealed lower left and right ventricle global longitudinal strain (−14.24% vs. −13.31%, p=0.03, and −18.12% vs. −15.95% p=0.01, respectively) and right ventricular (RV) global radial strain (19.28 vs 15.74, p<0.05) – Figure 1. There were no significant differences in LV global radial and circumferential strain. LV longitudinal, radial and circumferential systolic strain rate were also lower in athletes compared to controls (−0.69 s–1 vs. −0.78 s–1, p=0.04; 1.35 s–1 vs. 1.50 s–1, p=0.03: −0.92 s–1 vs −0.98 s–1, p=0.05, respectively). Regarding LV dyssynchrony index, we found no significant difference for L-SDI (10.76% vs. 10.72%, p=0.956), but athletes group showed lower C-SDI and R-SDI values (5.99% vs 4.84%, p=0.006, and 5.53% vs 4.47%, p=0.002).

Conclusion

Our study revealed attenuation of biventricular strain values and lower circumferential and radial LV dyssynchrony indexes in athletes, compared with healthy controls. We hypothesize that these differences may be related with exercise physiologic cardiac adaptations.

Funding Acknowledgement

Type of funding sources: None.

Predicting pacemaker dependency after TAVI with pre-procedural MSCT

Background and aim

High degree conduction disturbances is a burdensome complication of transcatheter aortic valve implantation (TAVI). There is limited data whether such disorders are permanent or reversible. Anatomic surrogates, such as membranous septum [MS, a distance marker from aortic annulus to His-bundle surge] and calcium distribution within aortic valve have been associated with pacemaker (PM) implantation. The aim of our study was to assess predictors of long-term pacemaker dependency following TAVI.

Methods

Single center prospectively included patients that underwent pacemaker implantation following TAVI (March 2017 to September 2020). Patients who were lost to follow up, with bicuspid aortic valve, previously implanted PM and non-available or low quality MSCT exam were excluded. On MSCT, MS length was measured on modified coronal view, the aortic-valvular complex (AVC) was characterized by leaflet sector and calcium distribution was assessed on a J-score threshold of 850-Hounsfield units. Pacemaker dependency was assessed by reducing ventricular pacing to 30 bpm and defined by subsequent complete AV dissociation in patients in sinus rhythm or an escape rhythm <50 bpm in atrial fibrillation, in addition of >90% pacing percentage since implantation.

Results

From the 352 patients with inclusion criteria, 67 underwent PM implantation (19%) and 55 included in the analysis (male 33.9%, median age=85) (Figure). Median time for pacemaker implantation was 3 days [interquartile range (IQR) 3–5 days], mostly due to complete auriculo-ventricular block (76.4%, N=42). PM dependency occurred in 14 out of 55 (25.5%) patients at mean follow up of 500±363 days. Patients with PM dependency tended to have deeper implantation depth, (6.2 mm vs 5.5 mm, p=0.096) and a significantly shorter MS (5.8 mm vs 6.8 mm, P-value = 0.031) (Table). Increasing MS length was independently associated with a lower risk of PM dependency [odds ratio (OR) 0.58 per mm; 95% CI: 0.35–0.98, p=0.04] regardless prosthesis choice. MS length under 5 mm had 97.6% specificity (95% CI: 87.1–99.9) and 85.7% positive predictive value for pacemaker dependency (AUC=76.7; 95% CI 63.3–87).

Conclusion

Our findings highlight the importance of MSCT-derived MS length to stratify the risk of long term need for pacemaker. Patients with short MS (<5mm) in addition to conduction abnormality following TAVI had a high likelihood of PM dependency on the long term and should be considered for prompt PM implantation.

Funding Acknowledgement

Type of funding sources: None.

Regurgitant volume to left ventricular end-diastolic volume ratio: the quest to identify Disproportionate MR is not over

Background

Quantification of secondary mitral valve regurgitation (SMR) remains challenging. Proportionate and Disproportionate SMR provides a conceptual framework that relates the degree of SMR to left ventricular dilatation and dysfunction. In line with this concept, regurgitant volume to LV end-diastolic volume ratio (Rvol/LVEDV) was recently proposed as a possible strategy to identify patients with Disproportionate SMR. The aim of this study was to validate this approach in a Portuguese cohort.

Methods

In a single center cohort of patients with heart failure and reduced left ventricular ejection fraction (HFrEF <50%) under optimal guideline-directed medical therapy (GDMT), we retrospectively identified those with at least moderate SMR. According to the published literature, we divided the study population into 2 risk groups: those with a Rvol/LVEDV ratio ≥20% (greater MR/smaller LVEDV) and those with a ratio <20% (smaller MR/ larger EDV). Cox regression and Kaplan-Meier survival analysis were used to assess the association between Rvol/LVEDV ratio and all-cause mortality.

Results

A total of 154 patients (mean age 69±12 years; 81% male) were included. Mean LVEF was 31±8% and median LVEDV was 193 mL (IQR: 155 to 236 mL). There were 74 patients (48.1%) with a Rvol/LVEDV ratio <20% and 80 patients (51.9%) Rvol/LVEDV ratio ≥20%. Regarding GDMT, 141 (91.6%) received beta-blockers, 139 (90.3%) angiotensin converting–enzyme inhibitors/angiotensin receptor blockers and 77 (50.0%) were under mineralocorticoid therapy. Also, there were patients 49 (31.8%) under cardiac resynchronization therapy and 40 patients (26.0%) had an implantable cardioverter defibrillator. During a median follow-up of 2.1 years (IQR 0.7 to 3.8 years), 92 (59.7%) patients died. Cox regression and survival analysis showed no mortality difference between patients with a Rvol/LVEDV ratio <20% and those with a ratio ≥20% (HR: 1.04; 95% CI 0.69–1.57; P=0.854; Log-rank P=0.967) – see also figure.

Conclusion

In a Portuguese cohort of HFrEF patients under optimized GDMT and with at least moderate SMR, the Rvol/LVEDV ratio was not associated with an increased risk of all-cause mortality. As such, the Rvol/LVEDV ratio does not seem to be a reliable surrogate of Disproportionate SMR, possibly because it does not account for the degree of LV dysfunction.

Funding Acknowledgement

Type of funding sources: None.

Coronary artery calcium score to predict coronary CT angiography interpretability. An old problem revisited

Introduction

Clinical guidelines recommend against the use of coronary computed tomography angiography (CCTA) in patients with heavy calcification due to interpretability concerns, but no specific approach or threshold is provided. Recently, alternative methods have been proposed as more reliable predictors of CCTA interpretability than the classic coronary artery calcium score (CACS). The purpose this study was to compare the performance of different measures of coronary calcification as predictors of CCTA interpretability.

Methods

We conducted a retrospective analysis of consecutive patients undergoing CACS and CCTA between 2018 and 2020. The key exclusion criteria were known coronary artery disease, CACS of zero, and presence of non-assessable coronary lesions for reasons other than calcification (movement/gating artifacts or vessel diameter <2mm). CCTA studies were considered non-interpretable if the main reader considered one or more coronary lesions non-assessable due to calcification. Three different measures of coronary calcification were compared using ROC curve analysis: 1) total CACS; 2) CACS-to-lesion ratio (total CACS divided by the number of calcified plaques); and 3) calcium score of the most calcified plaque. Decision-tree analysis was performed to identify the algorithm that best predicts CCTA interpretability.

Results

A total of 432 patients (191 women, mean age 64±11 years) were included. Overall, 31 patients (7.2%) had a non-interpretable CCTA due to calcification. Patients with non-interpretable CCTA had higher CACS (median 589 vs. 50 AU, p<0.001), higher CACS-to-lesion ratio (median 43 vs. 14 AU/lesion, p<0.001), and higher score of the most calcified plaque (median 445 vs. 43 AU, p<0.001). Among the 3 methods, CACS showed the highest discriminative power to predict a non-interpretable CCTA (C-statistic 0.93, 95% CI 0.89–0.95, p<0.001) – Figure 1.

Decision-tree analysis identified a single-variable algorithm (CACS value ≤515 AU) as the best discriminator of CCTA interpretability: 396 of the 409 patients (97%) with CACS ≤515 AU had an interpretable CCTA, whereas only 5 of the 23 patients (22%) with CACS >515 AU had an interpretable test, yielding a total of 96% correct predictions.

Conclusions

The recently proposed and more complex measures of coronary calcification seem unable to outperform total CACS as a predictor of CCTA interpretability. A simple CACS cutoff-value around 500 AU remains the best discriminator for this purpose.

Funding Acknowledgement

Type of funding sources: None. Figure 1

Patients undergoing invasive coronary angiography after a positive single-photon emission computed tomography or a positive stress cardiac magnetic resonance - What to expect at the cath lab

Funding Acknowledgements

Type of funding sources: None.

Background

 Randomized controlled trials comparing stress cardiac magnetic resonance (CMR) and single-photon emission computed tomography (SPECT) suggest similar diagnostic accuracy for detecting obstructive coronary artery disease (CAD). However, there are few data on whether or not this remains true in routine clinical practice.

The aim of this study was to assess the clinical and angiographic characteristics of patients undergoing invasive coronary angiography (ICA) after a positive stress CMR or positive SPECT, and to compare their positive predictive value with published results from the CE-MARC trial.

Methods

In this retrospective tertiary-center analysis, we included 429 patients (mean age 67 ± 10 years, 28% women, 42% diabetic) undergoing ICA between January 2016 and December 2020, after a positive stress CMR or positive SPECT. Regarding stress test, an adenosine protocol was performed in all stress CMR and in 76.4% (n = 272) of stress SPECT. 

Stress test results, including ischemia location and severity, were classified as reported by their primary readers. Patients with missing data on key variables, and those in whom microvascular disease was considered likely in the original stress test report were excluded. Obstructive CAD was defined as any coronary artery stenosis ≥ 50% in a vessel compatible with the ischemic territory on stress testing.

Results

Out of the total 429 patients, 356 (83%) were referred after a positive SPECT, and 73 (17%) after a positive stress CMR. Patients did not differ regarding age, cardiovascular risk factors, previous revascularization or left ventricular dysfunction, but patients with SPECT were more frequently male (p = 0.046). Overall, 320 patients (75%) had obstructive CAD on ICA. The prevalence of obstructive CAD was similar in patients with positive SPECT vs. positive stress CMR (76.1% vs. 80.8%, respectively, p = 0.385). There were also no significant differences in the prevalence of left main or 3-vessel disease (9.0% vs. 9.6%, p = 0.871, and 19.7% vs. 23.3% p = 0.483, respectively). Revascularization was performed or planned in 59.3% of patients in the SPECT group, and 52.1% of those in the stress CMR group (p = 0.255). The positive predictive values of both techniques were similar to those reported in the CE-MARC trial (Figure), and would increase to 88.1% and 89.4% for SPECT and stress CMR, respectively, if patients reported as having only mild ischemia were excluded.

Conclusion

In this tertiary center analysis, stress CMR and SPECT showed similar positive predictive values, comparable to those reported in the CE-MARC trial.

Calcium score of the aortic valve as a predictor of aortic stenosis severity

Funding Acknowledgements

Type of funding sources: None.

Background

The calcium score of the aortic valve (CaScAoV) is now recommended as a supporting tool to assist in the grading of aortic stenosis (AS) severity when echocardiographic assessment is inconclusive. However, the proposed CaScAoV cut-offs for considering severe AS "unlikely", "likely", or "very likely" have never been validated in Portuguese cohorts.

Aim

The purpose of this study was to assess the performance of the proposed CaScAoV cut-offs in identifying patients with severe aortic stenosis.

Methods

A total of 513 consecutive patients (median age 83 years [IQR 79–87], 38% males) evaluated at a single-centre TAVI-programme between Jan/2016 and Nov/2019 were retrospectively identified. Only patients with an ECG-gated cardiac computed tomography (CT) and a transthoracic echocardiography performed within a 6-month time-frame were included. Main exclusion criteria were left ventricular ejection fraction < 50%, indexed stroke volume < 35 ml/m2, previous valve surgery and

bicuspid aortic disease. CaScAoV was measured according to the Agatston method (Agatston units – AU). As previously reported, the likelihood of aortic stenosis as assessed by CT was categorized as: "very likely" (>3000 AU for men, >1600 AU for women); "likely" (>2000 AU for men, >1200 AU for women) ; or unlikely (<1600 AU for men, <800 AU for women). Diagnostic tests performance measures were calculated for each category. Separate analyses were performed for each gender.

Results

Severe AS (mean gradient ≥ 40 mmHg) was present in 422 patients (overall 82.3%: 83.1% in females and 80.8% in males), with a median transvalvular gradient of 49 mmHg (IQR 42 – 60).

Overall, the discriminative ability of the CaScAoV to distinguish severe from non-severe AS was higher in men when compared with women (c-statistic 0.86 [95%CI 0.80 – 0.93] vs. 0.72 [95%CI 0.64 – 0.80], p for comparison < 0.001). In males, the "very likely" cut-off had a sensitivity of 71% (95%CI 63 – 78%), a specificity of 81% (95%CI 65 – 92%), a positive predictive value (PPV) of 94% (95%CI 89 – 97%) and a negative predictive value (NPV) of 40% (95%CI 33 – 46%) for the diagnosis of severe AS. Conversely, in women the sensitivity was 75% (95%CI 69 – 80%), specificity was 57% (95%CI 43 – 71%), PPV was 90% (95%CI 86 – 92%) and NPV was 32% (95%CI 25 – 39%).

On the other end of the spectrum, the "unlikely" cut-off showed poor performance in dismissing severe AS, particularly in females – NPV of 43% (95%CI 25-63%) in women vs. 83% (95%CI 63-93%) in men.

Conclusion

In our population, the discriminative power of CaScAoV for identifying patients with severe AS was lower than in previously published cohorts, particularly in females. While very high CaScAoV is strongly supportive of severe AS, caution should be employed when interpreting low CaScAoV values in women, since the recommended cut-off value does not allow the safe exclusion of severe aortic stenosis.

Abstract Figure. Waterfall chart of individuals CaScAoV

The Role of Yeasts and Lactic Acid Bacteria on the Metabolism of Organic Acids during Winemaking

The main role of acidity and pH is to confer microbial stability to wines. No less relevant, they also preserve the color and sensory properties of wines. Tartaric and malic acids are generally the most prominent acids in wines, while others such as succinic, citric, lactic, and pyruvic can exist in minor concentrations. Multiple reactions occur during winemaking and processing, resulting in changes in the concentration of these acids in wines. Two major groups of microorganisms are involved in such modifications: the wine yeasts, particularly strains of Saccharomyces cerevisiae, which carry out alcoholic fermentation; and lactic acid bacteria, which commonly conduct malolactic fermentation. This review examines various such modifications that occur in the pre-existing acids of grape berries and in others that result from this microbial activity as a means to elucidate the link between microbial diversity and wine composition.

A FABP4-PPARγ signaling axis regulates human monocyte responses to electrophilic fatty acid nitroalkenes

Nitro-fatty acids (NO2-FA) are electrophilic lipid mediators derived from unsaturated fatty acid nitration. These species are produced endogenously by metabolic and inflammatory reactions and mediate anti-oxidative and anti-inflammatory responses. NO2-FA have been postulated as partial agonists of the Peroxisome Proliferator-Activated Receptor gamma (PPARγ), which is predominantly expressed in adipocytes and myeloid cells. Herein, we explored molecular and cellular events associated with PPARγ activation by NO2-FA in monocytes and macrophages. NO2-FA induced the expression of two PPARγ reporter genes, Fatty Acid Binding Protein 4 (FABP4) and the scavenger receptor CD36, at early stages of monocyte differentiation into macrophages. These responses were inhibited by the specific PPARγ inhibitor GW9662. Attenuated NO2-FA effects on PPARγ signaling were observed once cells were differentiated into macrophages, with a significant but lower FABP4 upregulation, and no induction of CD36. Using in vitro and in silico approaches, we demonstrated that NO2-FA bind to FABP4. Furthermore, the inhibition of monocyte FA binding by FABP4 diminished NO2-FA-induced upregulation of reporter genes that are transcriptionally regulated by PPARγ, Keap1/Nrf2 and HSF1, indicating that FABP4 inhibition mitigates NO2-FA signaling actions. Overall, our results affirm that NO2-FA activate PPARγ in monocytes and upregulate FABP4 expression, thus promoting a positive amplification loop for the downstream signaling actions of this mediator.

P2849Prevalence and significance of sustained pulmonary vein isolation in repeat AF ablation procedures

Introduction

Pulmonary vein (PV) reconnection is a common cause of relapse after catheter ablation of atrial fibrillation (AF). However, some patients have AF recurrence despite durable PV isolation. The aim of this study was to assess the PV isolation status at the time of a second catheter ablation (redo) procedure, and its relationship with subsequent AF relapse.

Methods

Consecutive patients with symptomatic drug-resistant AF who underwent redo procedures from January 2006 to December 2017 were identified in a single-center observational registry. Pulmonary vein isolation status was assessed during the electrophysiologic study with a circular mapping catheter. Additional radiofrequency (RF) energy applications were also recorded. AF relapse was defined as symptomatic or documented AF/atrial tachycardia/atrial flutter after a 3-month blanking period.

Results

We identified 240 patients (77 [32%] females, median age 61 [IQR 53–67] years, 85 [35%] with non-paroxysmal AF) undergoing redo procedures during the study period. At the time of redo, 17 (7%) of the patients presented bidirectional conduction block of all PVs. PV reconnection occurred in 157 (65%) of cases in the left superior vein, 142 (59%) in the left inferior vein, 177 (73%) in the right superior vein, and 163 (68%) in the right inferior vein (table). All of the PVs were reconducted in 91 (38%) patients. Additional RF applications were performed in the left atrium (LA) roof, LA posterior wall, cavotricuspid isthmus, mitral isthmus, superior vena cava, coronary sinus, and left atrial appendage ostium, at the operator's discretion (table 1).

Over a median follow-up of 2-years (IQR 1–5), 126 patients (53%) suffered AF recurrence, yielding a mean relapse rate of 17%/year. In multivariate Cox regression analysis, the lack of PV reconnection at the time of redo emerged as an independent predictor of subsequent relapse (HR 1.97, 95% CI 1.12–3.49, p=0.019) even after adjustment for univariate predictors including non-paroxysmal AF, body mass index, female sex, and active smoking.

Conclusion

In patients undergoing redo AF ablation procedures, less than 10% present with complete PV isolation. Despite being relatively infrequent, this finding is independently associated with greater likelihood of subsequent recurrence, suggesting that other mechanisms, not fully addressed by additional RF applications, are at play.

P5699Endocardial vs. epicardial ventricular tachycardia ablation: a propensity score matched analysis

Introduction

Direct comparisons of long-term clinical outcomes of endocardial vs. epicardial catheter ablation techniques for drug-resistant ventricular tachycardia (VT) have been scarcely reported.

We aim to compare the long-term efficacy and safety of endocardial vs. epicardial catheter ablation (END-ABL and EPI-ABL, respectively) in a propensity score (PS) matched population.

Methods

Single-center observational registry including 215 consecutive patients who underwent END-ABL (181) or EPI-ABL (n=34) for drug-resistant VT between January 2007 and June 2018. Efficacy endpoint was defined as VT-free survival after catheter ablation, while safety outcomes were defined by 30-days mortality and procedure-related complications. A propensity score was used to match patients in a 1:1 fashion according to the following variables: VT storm at presentation, left ventricular ejection fraction (LVEF), New York Heart Association (NYHA) class III/IV at presentation, ischemic ethology, presence of implantable cardioverter-defibrillator (ICD), and previous endocardial catheter ablation. Independent predictors of VT recurrence were assessed by Cox regression.

Results

The PS yielded two groups of 31 patients each well matched for baseline characteristics (Table 1). Over a median follow-up of 2 years (IQR 1–3), 58% (n=18) ENDO-ABL patients had VT recurrence vs. 26% (n=8) in the EPI-ABL group (P=0.020). The yearly rates of VT recurrence were 28%/year for END-ABL vs. 11%/year for EPI-ABL (P=0.021). Multivariate survival analysis identified previous endocardial ablation (HR= 3.52; 95% CI 1.17–10.54, p=0.026) and VT storm at presentation (HR=3.57; 95% CI 1.50–8.50, p=0.004) as independent predictors of VT recurrence. EPI-ABL was independently associated with fewer VT recurrences (HR=0.28; 95 CI 0.12–0.69, p=0.005), but only in patients with a previous endocardial ablation (p for interaction = 0.004) – Figure A.

No patients died at 30-days post-procedure. Hospital length of stay was similar between END-ABL and EPI-ABL (5 vs. 4 days respectively, p=0.139), as was the complication rate (6.5% vs. 12.9% respectively, p=0.390), although driven by different causes (Table 1).

Conclusion

VT storm at presentation and previous catheter ablation were independent predictors of VT recurrence. In patients with a previous failed endocardial catheter ablation, epicardial ablation seems to provide greater VT-free survival than repeat endocardial ablation. Both strategies seem equally safe.

1204Pericardial fat volume outperforms classic risk markers in the prediction of relapse after pulmonary vein isolation

Introduction

Pericardial adipose tissue has been implicated in the pathophysiology of atrial fibrillation (AF), but its relevance to clinical practice remains uncertain. The aim of this study was to assess the relative importance of pericardial fat as predictor of recurrence after pulmonary vein isolation (PVI).

Methods

We assessed 453 patients (278 men, age 61±13 years, 348 paroxysmal AF) with symptomatic AF undergoing cardiac CT prior to a PVI procedure. Pericardial fat was quantified on contrast-enhanced images using a new simplified semi-automated method. The study endpoint was symptomatic and/or documented AF recurrence.

Results

Over a median follow-up of 14 months (IQR 7–23), 170 patients (38%) relapsed. Survival analysis showed significant differences in AF-free survival across tertiles of pericardial fat (Figure). Pericardial fat volume was weakly correlated to body mass index [(BMI), Pearson's R=0.34]. After adjustment for BMI and other univariate predictors of relapse, three variables emerged independently associated with time to AF recurrence: non-paroxysmal AF (HR 2.08, 95% CI: 1.51–2.87, p<0.001), indexed left atrial (LA) volume (HR 1.02 per mL/m2, 95% CI: 1.01–1.02, p<0.001), and indexed pericardial fat volume (HR 1.50 per mL/m2, 95% CI: 1.37–1.64, p<0.001). Based on the Wald test, indexed pericardial fat volume was the strongest of these predictors of relapse (X2 values of 20, 13, and 77, respectively). The population attributable risk (PAF) was higher for pericardial fat (PAF=37% for 1st vs 4th quartile) vs LA volume (PAF=11% for 1st quartile vs 4th quartile) and non-paroxysmal AF (PAF=23%). Pericardial fat volume also showed greater discriminate power than indexed LA volume, with a C-statistic of 0.80 (95% CI 0.76–0.85) vs. 0.61 (95% CI 0.55–0.66), p for difference <0.001. The method for quantifying pericardial fat showed high inter-observer reproducibility (Pearson's R=0.90) and was quick to perform (38±3 seconds).

Conclusion

Pericardial fat volume is a strong independent predictor of AF relapse after PVI, outperforming classic risk markers such as LA volume and type of AF. The underlying mechanisms of this association deserve further study. Meanwhile, this simple parameter may help select patients who are more likely to derive sustained benefit from AF ablation.

Lactose-crosslinked fish gelatin-based porous scaffolds embedded with tetrahydrocurcumin for cartilage regeneration

Tetrahydrocurcumin (THC) is one of the major colourless metabolites of curcumin and shows even greater pharmacological and physiological benefits. The aim of this work was the manufacturing of porous scaffolds as a carrier of THC under physiological conditions. Fish-derived gelatin scaffolds were prepared by freeze-drying by two solutions concentrations (2.5% and 4% w/v), cross-linked via addition of lactose and heat-treated at 105 °C. This cross-linking reaction resulted in more water resistant scaffolds with a water uptake capacity higher than 800%. Along with the cross-linking reaction, the gelatin concentration affected the scaffold morphology, as observed by scanning electron microscopy images, by obtaining a reduced porosity but larger pores sizes when the initial gelatin concentration was increased. These morphological changes led to a scaffold's strength enhancement from 0.92 ± 0.22 MPa to 2.04 ± 0.18 MPa when gelatin concentration was increased. THC release slowed down when gelatin concentration increased from 2.5 to 4% w/v, showing a controlled profile within 96 h. Preliminary in vitro test with chondrocytes on scaffolds with 4% w/v gelatin offered higher metabolic activities and cell survival up to 14 days of incubation. Finally the addition of THC did not influence significantly the cytocompatibility and potential antibacterial properties were demonstrated successfully against Staphylococcus aureus.

Synthesis of bioinspired collagen/alginate/fibrin based hydrogels for soft tissue engineering

Hydrogels based on natural polymers offer a range of properties to mimic the native extracellular matrix, and provide microenvironments to preserve cellular function and encourage tissue formation. A tri-component hydrogel using collagen, alginate and fibrin (CAF) was developed and investigated at three collagen concentrations for application as a functional extracellular matrix analogue. Physical-chemical characterization of CAF hydrogels demonstrated a thermo-responsive crosslinking capacity at physiological conditions with stiffness similar to native soft tissues. CAF hydrogels were also assessed for cytocompatibility using L929 murine fibroblasts, pancreatic MIN6 β-cells and human mesenchymal stem cells (hMSCs); and demonstrated good cell viability, proliferation and metabolic activity after 7 days of in vitro culture. CAF hydrogels, especially with 2.5% w/v collagen, increased alkaline phosphatase production in hMSCs indicating potential for the promotion of osteogenic activity. Moreover, CAF hydrogels also increased metabolic activity of MIN6 β-cells and promoted the reconstitution of spherical pseudoislets with sizes ranging between 50 and 150 μm at day 7, demonstrating potential in diabetic therapeutic applications.

Alginate-based hydrogels functionalised at the nanoscale using layer-by-layer assembly for potential cartilage repair

Injuries to articular cartilage are frequently difficult to repair, in part because of the poor regenerative capacity of this tissue. To date, no successful system for complete regeneration of the most challenging cartilage defects has been demonstrated. The aim of this work was to develop functionalised hydrogels at the nanoscale by Layer-by-Layer (LbL) assembly to promote cartilage healing. Hydrogels, based on sodium alginate (NaAlg) and gelatin (G), were prepared by an external gelation method consisting of CaCl₂ diffusion and genipin addition for G crosslinking. Successively, hydrogels were coated with G to obtain a positive charge on the surface, then functionalised by LbL assembly to create 16 nanolayers, based on poly(styrene sulfonate)/poly(allyl amine) (PSS/PAH), including a specific peptide sequence (CTATVHL) and transforming growth factors β1 (TGF-β1). Physico-chemical properties were evaluated by XPS, ATR-FTIR and rheological analyses while in vitro cytocompatibility was studied using bovine articular chondrocytes (BAC). XPS spectra showed N_1s and S_2p peaks, indicating that PAH and PSS have been introduced with success. ATR-FTIR indicated the specific PAH and PSS absorption peaks. Finally, the biomolecule incorporation influenced positively the processes of BAC adhesion and proliferation, and glycosamynoglycan secretion. The functionalised alginate-based hydrogels described here are ideally suited to chondral regeneration in terms of their integrity, stability, and cytocompatibility.