Pro-regenerative biomaterials recruit immunoregulatory dendritic cells after traumatic injury

During wound healing and surgical implantation, the body establishes a delicate balance between immune activation to fight off infection and clear debris and immune tolerance to control reactivity against self-tissue. Nonetheless, how such a balance is achieved is not well understood. Here we describe that pro-regenerative biomaterials for muscle injury treatment promote the proliferation of a BATF3-dependent CD103+XCR1+CD206+CD301b+ dendritic cell population associated with cross-presentation and self-tolerance. Upregulation of E-cadherin, the ligand for CD103, and XCL-1 in injured tissue suggests a mechanism for cell recruitment to trauma. Muscle injury recruited natural killer cells that produced Xcl1 when stimulated with fragmented extracellular matrix. Without cross-presenting cells, T-cell activation increases, pro-regenerative macrophage polarization decreases and there are alterations in myogenesis, adipogenesis, fibrosis and increased muscle calcification. These results, previously observed in cancer progression, suggest a fundamental mechanism of immune regulation in trauma and material implantation with implications for both short- and long-term injury recovery.

Emergency pacemaker implantation in nonagenarians with complete heart block: is single chamber pacing sufficient?

Background

In ambulatory patients with complete heart block and preserved sinus node activity (CHBs), dual chamber pacing confers well-established physiological benefits versus single chamber pacing. There is limited evidence as to whether these benefits extend to very frail patients, especially those over 90 years of age.

Purpose

In nonagenarians presenting with emergent CHBs from 2016–2019, we compared the clinical characteristics of patients selected for single versus dual chamber pacemakers (PPM), and evaluated the symptomatic and prognostic implications of these devices.

Methods

Baseline characteristics were discerned from electronic records, and physiological data extracted from serial PPM interrogations. Frailty was quantified according to the Rockwood clinical frailty scale (1–9). Cause of death was provided by the patients' General Practitioner. Cox proportional hazards analysis (HR, 95% CI) examined associations with all-cause mortality and death from congestive cardiac failure (CCF).

Results

168 consecutive patients were included (44.3% Male, Median age: 91 (2) years) and followed-up for 26.9±14.6 months. 22 patients (13.1%) were implanted with single chamber pacemakers (all programmed VVIR); when compared with patients receiving dual chamber devices, these patients had similar median age (93 (3) versus 91 (2) years, p=0.15) and LV systolic function (LVEF: 49.2% ±9.7 versus 50.7% ±10.1, p=0.71), but were more frail (Rockwood scale: 5.2±1.8 versus 4.3±1.1, p=0.004) and more likely to have severe cognitive impairment (27.3% versus 9.2%, p=0.018). Post implant, patients who received single chamber devices had higher average respiratory rates (21.3±2.4 breaths per minute versus 17.5±2.6 breaths per minute, p=0.002), lower average heart rates (65.5±10.1 bpm versus 71.9±8.6 bpm, p=0.002), and lower daily activity levels (0.57±0.3 hours of activity versus 1.5±1.1 hours of activity, p=0.016) than those with dual chamber devices. Death from CCF was more common in patients receiving single chamber devices (40.9% versus 6.2%, log rank p<0.0001); this association persisted when adjusting for age, frailty and cognitive impairment (adjusted HR: 6.2 (2.2–17.3, p=0.0005). However, in this age group, single chamber pacing was not independently associated with all-cause mortality when compared with dual chamber pacing (adjusted HR: 1.9 (0.95–3.6, p=0.07).

Conclusions

In nonagenarians with CHBs, dual chamber pacing was associated with improved symptomatic outcomes and a reduced risk of death from CCF, but did not affect all-cause mortality when compared with single chamber pacing.

Funding Acknowledgement

Type of funding sources: None.

Cardiac implantable electronic device infections: prognostic value of the PADIT score and its cost-utility implications for antimicrobial envelope use in the United Kingdom

Background

The incidence of cardiac implantable electronic device (CIED) infections is rising.

Purpose

We examined the factors associated with CIED infection, assessed the prognostic power of the PADIT risk score, and modelled the cost-utility of selective TYRX antimicrobial envelope use for preventing CIED infections.

Methods

Data were extracted from 2016 to 2019, and included all de novo implants, generator changes and lead interventions for transvenous CIEDs at a high-volume UK centre. CIED infection was defined as hospitalisation for device infection within 12 months of a procedure. Cost-utility analysis was informed by standardised tariffs, and quality adjusted life year (QALY) and efficacy data was extrapolated from analysis of the WRAP-IT trial.

Results

6,035 patients underwent 7,383 procedures; CIED infection occurred in 59 individuals (0.8%). In addition to the constituents of the PADIT score, lead extraction (HR 3.3 (1.9–6.1), p<0.0001), C-reactive protein >50mg/l (HR 3.0 (1.4–6.4), p=0.005), re-intervention within two years (HR 10.1 (5.6–17.9), p<0.0001), and procedure duration over two hours (HR 2.6 (1.6–4.1), p=0.001) were independent predictors of infection. Increased PADIT score was strongly associated with infection (AUC: 0.82, HR per point increase: 1.36 (1.27–1.47), p<0.0001). A cost-utility model assigning TYRX envelopes to patients with PADIT scores ≥6 predicted a reduction in infections (number needed to treat: 72) and a cost per QALY gained within the UK's (NICE) cost-effectiveness threshold (£25,107).

Conclusions

The PADIT score was a powerful predictor of CIED infections in a heterogeneous population,and may facilitate cost-effective TYRX envelope allocation in selected high-risk patients.

Funding Acknowledgement

Type of funding sources: None.

Transseptal puncture for left atrial ablation: risk factors for cardiac tamponade and a proposed causative classification system

Background

Cardiac tamponade is a high morbidity complication of transseptal puncture (TSP).

Purpose

We examined the associations of TSP-related cardiac tamponade (TRCT) for all patients undergoing left atrial ablation at our centre from 2016–2020.

Methods

Patient and procedural variables were extracted retrospectively. Cases of cardiac tamponade were scrutinised to adjudicate TSP culpability. Adjusted multivariate analysis examined predictors of TRCT.

Results

3,239 consecutive TSPs were performed; cardiac tamponade occurred in 51 patients (incidence: 1.6%) and was adjudicated as TSP-related in 35 (incidence: 1.1%; 68.6% of all tamponades). Patients of above-median age (OR 2.4 (1.19–4.2), p=0.006) and those undergoing re-do procedures (OR 1.95 (1.29–3.43, p=0.042) were at higher risk of TRCT. Of the operator-dependent variables, choice of transseptal needle (Endrys vs Brockenbrough, p>0.1) or puncture sheath (Swartz vs Mullins vs Agilis vs Vizigo vs Cryosheath, all p>0.1) did not predict TRCT. Adjusting for operator, equipment and demographics, failure to cross the septum first pass increased TRCT risk (OR 4.42 (2.45–8.2), p=0.001), whilst top quartile operator experience (OR 0.4 (0.17–0.85, p=0.002), transoesophageal echocardiogram (TOE prevalence: 26%, OR 0.51 (0.11–0.94), p=0.023), and use of the SafeSept guidewire (OR 0.22 (0.08–0.62), p=0.001) reduced TRCT risk. An increase in SafeSept wire use over time (2016: 15.6%, 2020: 60.2%) correlated with an annual reduction in TRCT (R2=0.72, p<0.001) and was associated with a relative risk reduction of 70%.

Conclusions

During left atrial ablation, the independent predictors of TRCT were patient age, re-do procedure, operator experience, unsuccessful first pass, TOE-guidance, and use of the SafeSept wire. A novel classification system for the causes of cardiac tamponade is proposed (table 1); this may be of interest to clinical trialists or auditors evaluating patient safety.

Funding Acknowledgement

Type of funding sources: None.

1051 EMERGENCY PACEMAKER IMPLANTATION IN NONAGENARIANS: IMPACT OF FRAILTY ON OPERATOR DECISION-MAKING AND PATIENT OUTCOMES

Introduction

Complete heart block (CHB) is a time-critical emergency. In frail patients with CHB, the absence of test results or a comprehensive history can challenge operator decision-making; in particular, minimal data exists as to the prognostic impact of single versus dual chamber pacing in this group. In patients over 90 years of age presenting with CHB, we examined the prognostic value of parameters obtained from bedside examination, and analysed the impact of single versus dual chamber pacemakers on mortality.

Method

Data were extracted from 2016–2019. Bedside covariates were age, sex, previous cardiac surgery, atrial rhythm, LV systolic function, syncope at presentation, QRS duration, and Rockwood frailty score. Cox-proportional hazards regression examined associations with all-cause mortality and cardiac death, determined from electronic records and death certificates (adjusted HR, 95% CI).

Results

205 patients were included (age 92.3 ± 2.3 years, 45.4% male). Mortality was 13.8% at 90 days and 27.2% at 27.1 ± 16.7 months. The independent predictors of mortality were pre-procedural QRS duration >130 ms (HR 2.4 (1.4–4.1) p = 0.001), age (HR 1.07 (1.02–1.15) p = 0.004), AF (HR 2.0 (1.1–3.6) p = 0.02), and Rockwood score (HR 1.2 (1.02–2.6), p = 0.043). Sex, syncope at presentation, LV function or previous cardiac surgery did not predict mortality (all p > 0.1). In a subset of 168 patients without AF, 30 (17.8%) received single chamber pacemakers. Whilst these patients were more frail than those receiving dual chamber pacemakers (Rockwood scores: 5.2 ± 1.7 vs 4.3 ± 1.1, p = 0.025), implantation of a single chamber pacemaker was independently associated with cardiac death when adjusting for frailty and co-morbidities (HR 6 (1.4–26.4), p = 0.018).

Conclusion

Nonagenarians undergoing emergency pacemaker implantation have a reasonable prognosis. Data ascertained at the bedside can help predict survival, however—when adjusting for frailty and co-morbidities—dual chamber pacing may confer an independent mortality benefit over single chamber pacing in this group.

Transseptal puncture for left atrial ablation: risk factors for cardiac tamponade and a proposed causative classification system

Aims

Cardiac tamponade is a high morbidity complication of transseptal puncture (TSP). We examined the associations of TSP‐related cardiac tamponade (TRCT) for all patients undergoing left atrial ablation at our center from 2016 to 2020.

Methods and Results

Patient and procedural variables were extracted retrospectively. Cases of cardiac tamponade were scrutinized to adjudicate TSP culpability. Adjusted multivariate analysis examined predictors of TRCT. A total of 3239 consecutive TSPs were performed; cardiac tamponade occurred in 51 patients (incidence: 1.6%) and was adjudicated as TSP‐related in 35 (incidence: 1.1%; 68.6% of all tamponades). Patients of above‐median age [odds ratio (OR): 2.4 (1.19–4.2), p = .006] and those undergoing re‐do procedures [OR: 1.95 (1.29–3.43, p = .042] were at higher risk of TRCT. Of the operator‐dependent variables, choice of transseptal needle (Endrys vs. Brockenbrough, p > .1) or puncture sheath (Swartz vs. Mullins vs. Agilis vs. Vizigo vs. Cryosheath, all p > .1) did not predict TRCT. Adjusting for operator, equipment and demographics, failure to cross the septum first pass increased TRCT risk [OR: 4.42 (2.45–8.2), p = .001], whilst top quartile operator experience [OR: 0.4 (0.17–0.85), p = .002], transoesophageal echocardiogram [TOE prevalence: 26%, OR: 0.51 (0.11–0.94), p = .023], and use of the SafeSept transseptal guidewire [OR: 0.22 (0.08–0.62), p = .001] reduced TRCT risk. An increase in transseptal guidewire use over time (2016: 15.6%, 2020: 60.2%) correlated with an annual reduction in TRCT (R² = 0.72, p < .001) and was associated with a relative risk reduction of 70%.

Conclusions

During left atrial ablation, the risk of TRCT was reduced by operator experience, TOE‐guidance, and use of a transseptal guidewire, and was increased by patient age, re‐do procedures, and failure to cross the septum first pass.

Explanation-visualised deep learning model for accessory pathway localisation using 12-lead electrocardiography

Funding Acknowledgements

Type of funding sources: Public Institution(s). Main funding source(s): British Heart Foundation Imperial Centre of Research Excellence

Background/Introduction

ECG algorithms for identifying accessory pathway (AP) locations are inaccurate and difficult to use. Human expert interpretation is poorly reproducible. Artificial intelligence (AI) techniques such as machine learning can improve accuracy in classification tasks by eschewing theory-driven predictions. More reproducible and accurate AP localisation could shorten procedure time and personalise ablation consent.

Purpose

We developed a neural network to perform AP localisation using 12-lead ECGs. Its decision-making process was analysed to enable explainability of the neural network.

Methods

A convolutional neural network was trained on raw, digital, intra-procedural 12-lead ECGs of patients with manifest APs who underwent successful ablation. ECGs were labelled with AP locations as left-sided, septal or right-sided using procedure reports, fluoroscopy and electro-anatomical maps. Accuracy of the neural network was assessed via 4-fold cross-validation and was compared to the Arruda algorithm. Five cardiologists were also assessed for their accuracy in determining locations in sub-groups of cases. The neural network was retrospectively analysed to identify areas of ECGs most influential to its predictions using importance mapping.

Results 

In 156 cases, accuracy of the neural network (92.9%) was significantly higher than the Arruda algorithm (76.9%; p &lt; 0.0001) and all five cardiologists (37.5% to 65.9%; p = 0.0001 to 0.0290). Importance mapping demonstrated that the QRS complexes of leads aVL and V1 were perceived as most influential, indicating interrogation of the lateral and anterior-posterior axes respectively.

The figure shows (A) architecture of the neural network, (B) accuracy of the neural network, Arruda algorithm and five cardiologists, (*, p = 0.05 – 0.01; **, p = 0.01 – 0.001; ***, p = 0.001 - 0.0001; ****, p &lt; 0.0001; as compared to the neural network) and (C) example importance maps for 12-lead ECGs of left-sided, septal and right-sided APs (in order from left to right), with darker regions corresponding to greater relative importance. 

Conclusion 

AI ECG interpretation allows accurate, reproducible prediction of AP locations, superior to conventional algorithms and human interpretation. Although AI decision-making is thought of as a ‘black box’, explanation visualisation techniques such as importance mapping allow humans to understand aspects of how a neural network make decisions. A prospectively validated neural network could be integrated into clinical practice to improve pre-procedural AP localisation. Abstract Figure. Summary of results

ProGlide venous closure device facilitates early ambulation following cryoablation of atrial fibrillation

Funding Acknowledgements

Type of funding sources: Foundation. Main funding source(s): Heart Foundation

Background

Same-day discharge following atrial fibrillation (AF) ablation is increasingly common. ProGlide device suture-mediated vascular closure (PD) offers a technique that may expedite mobilisation following large-bore (&gt;12F) venous access. The utility of PD closure following cryoablation of AF has not been reported.

Purpose

We sought to evaluate haemostasis and early ambulation outcomes in patients receiving the ProGlide compared with conventional techniques.

Methods

104 consecutive patients undergoing cryoballoon pulmonary vein isolation (PVI) for paroxysmal or persistent at a single high-volume institution were included. PVI was  performed via a standardised approach including sedation, ultrasound-guided vascular access for 14F Cryosheath and second 7F sheath, anticoagulation protocol, transeptal puncture, 28mm cryoballoon and nurse-led same-day discharge protocol. Haemostasis was achieved using the Perclose Proglide device (PD) in the 14F access point ("pre-closure" technique) plus 5 minutes manual pressure at the 7F sheath site. Alternatively, a figure-of-eight/Z-suture (ZS) was employed for closure according to operator preference. Protamine was used for heparin reversal in all patients. Safety outcomes of major bleeding, haematoma and minor bleeding were assessed. Time to ambulation (TTA), time to discharge (TTD), same-day discharge and complications at initial follow-up were measured.

Results

Overall, mean age was 64 ± 11 years, 65 (64%) were male and 52 (50%) of patients had paroxysmal AF, there were no significant differences between group demographics, with 31 patients (30%) in the PD group and 73 (70%) in the ZS group. All patients had uninterrupted oral anticoagulation throughout the periprocedural period. No major femoral bleeding complications requiring intervention occurred in either group. Haematomas occurred in none of the PD group compared with 2 (2.8%) in the ZS group. Incidence of minor bleeding was not significantly different between groups (PD: 3 [9.7%] vs ZS: 2 [2.7%], p = 0.155). Mean TTA was significantly shorter in the PD group (3.3 ± 1.1 vs 4.1 ± 1.7 hrs, p = 0.025). However, there was no significant difference in same-day discharge (PD: 25 [81%] vs ZS: 53 [73%], p = 0.386) and TTD (5.0 ± 3.6 vs 6.1 ± 4.2 hrs, p = 0.275) between groups. 1 patient complained of groin pain which delayed discharge in the ZS group not seen in the PD group. After a mean follow-up of 2.2 ± 1.4 months, there were no differences in major or minor complications.

Conclusion

Use of the Proglide closure device was associated with significant reductions in time to ambulation compared with Z-suture haemostasis following cryoablation of AF, and groin access complications were uncommon across groups.  PD closure may contribute to further streamlining patient pathways in day-case AF ablation.

Initial experience with the convergent procedure for longstanding persistent atrial fibrillation: A 5 year dataset

In patients with longstanding persistent atrial fibrillation (AF), outcomes from catheter ablation remain suboptimal. The convergent procedure combines minimally invasive surgical ablation with subsequent catheter ablation, and may contribute towards maintenance of sinus rhythm in this patient group. We performed the convergent procedure on 43 patients with longstanding persistent AF from 2013–2018. Patients underwent clinical review at 3, 6, and 12 months and thereafter as necessitated by their symptoms. Our dataset describes patients’ baseline characteristics and rhythm control protocols, as well as outcomes including arrhythmia recurrence, the need for antiarrhythmic drugs, requirement for repeat rhythm control procedures, and complications. These data provide a real world insight into the risks and benefits of the convergent procedure in patients with longstanding persistent AF.

Identifying avoidable switchboard delays in England's NHS hospitals: phase one of the national SWITCH project

BACKGROUND

Inter-hospital communication frequently requires mediation via a switchboard. Identifying and eliminating switchboard inefficiencies may improve patient care.

METHODS

All 175 acute hospital switchboards in England were contacted six times. Call contents and duration were recorded. No clinician calls or bleeps were connected.

RESULTS

The mean delay before contacting a switchboard operative was 55±46 seconds. 115 hospitals (66%) used automated switchboards; 34 of these (30%) had infection control messages. Robot operators introduced an additional 40 second delay versus humans (mean 70.3±28 versus 29.8±23 seconds, p<0.0001). Multivariate analysis identified robot operators (HR 5.1, p<0.0001) and infection control messages (HR 2.9, p=0.003) as predictors of delays over 60 seconds.

CONCLUSIONS

There are significant avoidable delays in contacting switchboard operatives across England. Quality improvement is underway.

The effect of high-protein, low-carbohydrate diets in the treatment of type 2 diabetes: a 12 month randomised controlled trial

AIMS/HYPOTHESIS

Short-term dietary studies suggest that high-protein diets can enhance weight loss and improve glycaemic control in people with type 2 diabetes. However, the long-term effects of such diets are unknown. The aim of this study was to determine whether high-protein diets are superior to high-carbohydrate diets for improving glycaemic control in individuals with type 2 diabetes.

METHODS

Overweight/obese individuals (BMI 27-40 kg/m(2)) with type 2 diabetes (HbA(1c) 6.5-10%) were recruited for a 12 month, parallel design, dietary intervention trial conducted at a diabetes specialist clinic (Melbourne, VIC, Australia). Of the 108 initially randomised, 99 received advice to follow low-fat (30% total energy) diets that were either high in protein (30% total energy, n = 53) or high in carbohydrate (55% total energy, n = 46). Dietary assignment was done by a third party using computer-generated random numbers. The primary endpoint was change in HbA(1c). Secondary endpoints included changes in weight, lipids, blood pressure, renal function and calcium loss. Study endpoints were assessed blinded to the diet group, but the statistical analysis was performed unblinded. This study used an intention-to-treat model for all participants who received dietary advice. Follow-up visits were encouraged regardless of dietary adherence and last measurements were carried forward for study non-completers.

RESULTS

Ninety-nine individuals were included in the analysis (53 in high protein group, 46 in high carbohydrate group). HbA(1c) decreased in both groups over time, with no significant difference between groups (mean difference of the change at 12 months; 0.04 [95% CI -0.37, 0.46]; p = 0.44). Both groups also demonstrated decreases over time in weight, serum triacylglycerol and total cholesterol, and increases in HDL-cholesterol. No differences in blood pressure, renal function or calcium loss were seen.

CONCLUSIONS/INTERPRETATION

These results suggest that there is no superior long-term metabolic benefit of a high-protein diet over a high-carbohydrate in the management of type 2 diabetes.

TRIAL REGISTRATION

ACTRN12605000063617 ( www.anzctr.org.au ).

FUNDING

This study was funded by a nutritional research grant from Meat and Livestock Australia (MLA). J.E. Shaw is supported by NHMRC Fellowship 586623.

An investigation into the health-related quality of life of individuals living with HIV who are receiving HAART

The health authorities have recently accepted the routine provision of highly active antiretroviral therapy to persons living with AIDS in South Africa. There is a need to investigate the impact of HAART on the health-related quality of life of people living with HIV/AIDS (PLWHA) in a resource-poor environment, as this will have an influence on compliance and treatment outcome. The aim of this study was to explore whether HAART is efficacious in improving the self-reported health-related quality of life (HRQoL) in a group of PWLA in WHO Stages 3 and 4 living in a resource-poor community. A quasi-experimental, prospective repeated measures design was used to monitor the HRQoL over time in participants recruited to an existing HAART programme. The HRQoL of 117 participants was determined through the use of the Xhosa version of the EQ-5D and measurements were taken at baseline, one, six and 12 months. At the time of the 12-month questionnaire, 95 participants had been on HAART for 12 months. Not all participants attended all follow-up visits, but only two participants had withdrawn from the HAART programme, after two or three months. At baseline, the rank order of problems reported in all domains of the EQ-5D was significantly greater than at 12 months. The mean score on the global rating of health status increased significantly (p < 0.001) from a mean of 61.7 (SD = 22.7) at baseline to 76.1 at 12 months (SD = 18.5) It is concluded that, even in a resource-poor environment, HRQoL can be greatly improved by HAART, and that the possible side effects of the drugs seem to have a negligible impact on the wellbeing of the subjects. This bodes well for the anticipated roll-out of HAART within the public health sector in South Africa.

Postprandial triglycerides in response to high fat: role of dietary carbohydrate

BACKGROUND

The postprandial triglyceride response following a meal high in fat (HFM) has been related to atherogenesis and insulin resistance. We examined the influence of dietary carbohydrate and the accompanying insulin secretory response on the postprandial triglyceride response following a HFM. MATERIALS AND DESIGN: High-fat meals of equal fat content (fat 80 g) containing either 20 g (low) or 100 g (high) of carbohydrate (HFM-LC and HFM-HC, respectively), and therefore not isocaloric (4250 kJ of HFM-LC and 5450 kJ of HFM-HC), were consumed by seven (four male, three female) normolipidaemic subjects (aged 32.9 +/- 3.7 years, BMI 24.7 +/- 1.8 kg m-2). Blood and indirect calorimetry data were collected at 0-4 h.

RESULTS

HFM-HC produced a significant rise in plasma glucose (Delta0.54 +/- 0.23 mmol L-1, P = 0.05) at 2 h, while a HFM-LC elicited no mean change from baseline. Following a HFM-LC, the plasma insulin incremental area under the curve (AUC) was significantly lower (31.3 +/- 6.7 vs. 83.2 +/- 11.9 mU l-1 h-1, P < 0.0003) and the postprandial triglyceride response AUC was significantly greater (1.66 +/- 0.36 vs. 1.24 +/- 0.31 mmol L-1 h-1, P < 0.006) compared with a HFM-HC. Plasma free fatty acids were suppressed by 44% (P = 0.04) and 66% (P < 0.0001) at 1 h following HFM-LC and HFM-HC, respectively, compared with baseline. There were no significant differences between the meals in energy expenditure, substrate oxidation rates, or respiratory quotient responses.

CONCLUSIONS

By design, the HFMs were not isocaloric but the presence of carbohydrate in a HFM invoked an insulin response that significantly reduced the 4 h postprandial triglyceride response even in healthy, normolipidaemic subjects. This phenomenon may have clinical implications, particularly in relation to insulin sensitivity.