Arrhythmias and cardiac MRI associations in patients with established cardiac dystrophinopathy

AIMS

Some patients with cardiac dystrophinopathy die suddenly. Whether such deaths are preventable by specific antiarrhythmic management or simply indicate heart failure overwhelming medical therapies is uncertain. The aim of this prospective, cohort study was to describe the occurrence and nature of cardiac arrhythmias recorded during prolonged continuous ECG rhythm surveillance in patients with established cardiac dystrophinopathy and relate them to abnormalities on cardiac MRI.

METHODS AND RESULTS

A cohort of 10 patients (36.3 years; 3 female) with LVEF<40% due to Duchenne (3) or Becker muscular (4) dystrophy or Duchenne muscular dystrophy-gene carrying effects in females (3) were recruited, had cardiac MRI, ECG signal-averaging and ECG loop-recorder implants. All were on standard of care heart medications and none had prior history of arrhythmias.No deaths or brady arrhythmias occurred during median follow-up 30 months (range 13-35). Self-limiting episodes of asymptomatic tachyarrhythmia (range 1-29) were confirmed in 8 (80%) patients (ventricular only 2; ventricular and atrial 6). Higher ventricular arrhythmia burden correlated with extent of myocardial fibrosis (extracellular volume%, p=0.029; native T1, p=0.49; late gadolinium enhancement, p=0.49), but not with LVEF% (p=1.0) on MRI and atrial arrhythmias with left atrial dilatation. Features of VT episodes suggested various underlying arrhythmia mechanisms.

CONCLUSIONS

The overall prevalence of arrhythmias was low. Even in such a small sample size, higher arrhythmia counts occurred in those with larger scar burden and greater ventricular volume, suggesting key roles for myocardial stretch as well as disease progression in arrhythmogenesis. These features overlap with the stage of left ventricular dysfunction when heart failure also becomes overt. The findings of this pilot study should help inform the design of a definitive study of specific antiarrhythmic management in dystrophinopathy.

TRIAL REGISTRATION NUMBER

ISRCTN15622536.

Ventricular assist devices in transposition and failing systemic right ventricle: role of tricuspid valve replacement

OBJECTIVES

Ventricular assist device (VAD) for systemic right ventricular (RV) failure patients post-atrial switch, for transposition of the great arteries (TGA), and those with congenitally corrected TGA has proven useful to reduce transpulmonary gradient and bridge-to-transplantation. The purpose of this study is to describe our experience of VAD in systemic RV failure and our move towards concomitant tricuspid valve replacement (TVR).

METHODS

This is a single-centre retrospective study of consecutive adult patients receiving HeartWare VAD for systemic RV failure between 2010 and 2019. From 2017, concomitant TVR was performed routinely. Demographic, clinical variables and echocardiographic and haemodynamic measurements pre- and post-VAD implantation were recorded. Complications on support, heart transplantation and survival rates were described.

RESULTS

Eighteen patients underwent VAD implantation. Moderate or severe systemic tricuspid regurgitation was present in 83.3% of patients, and subpulmonic left ventricular impairment in 88.9%. One-year survival was 72.2%. VAD implantation was technically feasible and successful in all but one. Post-VAD, transpulmonary gradient fell from 16 (15-22) to 10 (7-13) mmHg (P = 0.01). Patients with TVR (n = 6) also demonstrated a reduction in mean pulmonary and wedge pressures. Furthermore, subpulmonic left ventricular end-diastolic dimension (44.3 vs 39.6 mm; P = 0.03) and function improved in this group. After 1 year of support, 72.2% of patients were suitable for transplantation.

CONCLUSIONS

VAD is an effective strategy as bridge-to-candidacy and bridge-to-transplantation in patients with end-stage systemic RV failure. Concomitant TVR at the time of implant is associated with better early haemodynamic and echocardiographic results post-VAD.

Does infection predispose to thrombosis during long term ventricular assist device support?

BACKGROUND

Infections and thrombotic events remain life-threatening complications in patients with ventricular assist devices (VAD).

METHODS

We describe the relationship between both events in our cohort of patients (n=220) supported with the HeartWare VAD (HVAD). This is a retrospective analysis of patients undergoing HVAD implantation between July 2009 and March 2019 at the Freeman Hospital, Newcastle upon Tyne, United Kingdom.

RESULTS

Infection was the most common adverse event in HVAD patients, with 125 patients (56.8%) experiencing ≥ one infection (n=168, 0.33 event-per-person-year-EPPY), followed by pump thrombosis (PT) in 61 patients (27.7%, 0.16 EPPY). VAD-specific infections were the largest group of infections. Of the 125 patients who had an infection, 66 (53%) had a thrombotic event. Both thrombotic events and infections were related to the duration of support, though there was only limited evidence that infections predispose to thrombosis. Those with higher than median levels of CRP during the infection were more likely to have an ischaemic stroke (IS) (34.5% vs 16.7%, p=0.03), though not PT or a combined thrombotic event (CTE: first PT or IS). However, in multivariate analysis there was no significant effect of infection predisposing to CTE.

CONCLUSIONS

Infection and thrombotic events are significant adverse events related to the duration of support in patients receiving HVADs. Infections do not clearly predispose to thrombotic events.

Markers of Right Ventricular Dysfunction Predict Maximal Exercise Capacity After Left Ventricular Assist Device Implantation

Although left ventricular assist device (LVAD) improves functional capacity, on average LVAD patients are unable to achieve the aerobic capacity of normal healthy subjects or mild heart failure patients. The aim of this study was to examine if markers of right ventricular (RV) function influence maximal exercise capacity. This was a single-center prospective study that enrolled 20 consecutive HeartWare ventricular assist device patients who were admitted at the Freeman Hospital (Newcastle upon Tyne, United Kingdom) for a heart transplant assessment from August 2017 to October 2018. Mean peak oxygen consumption (Peak VO2) was 14.0 ± 5.0 ml/kg/min, and mean peak age and gender-adjusted percent predicted oxygen consumption (%VO2) was 40.0% ± 11.5%. Patients were subdivided into two groups based on the median peak VO2, so each group consisted of 10 patients (50%). Right-sided and pulmonary pressures were consistently higher in the group with poorer exercise tolerance. Patients with poor exercise tolerance (peak VO2 below the median) had higher right atrial pressures at rest (10.6 ± 6.4 vs. 4.3 mmHg ± 3.2; p = 0.02) and the increase with passive leg raising was significantly greater than those with preserved exercise tolerance (peak VO2 above the median). Patients with poor functional capacity also had greater RV dimensions (4.4 cm ± 0.5 vs. 3.7 cm ± 0.5; p = 0.02) and a higher incidence of significant tricuspid regurgitation (moderate or severe tricuspid regurgitation in five patients in the poor exercise capacity group vs. none in the preserved exercise capacity group; p = 0.03). In conclusion, echocardiographic and hemodynamic markers of RV dysfunction discriminate between preserved and nonpreserved exercise capacity in HeartWare ventricular assist device patients.

Initial conservative management strategy of HeartWare left ventricular assist device thrombosis with intravenous heparin or bivalirudin

Introduction and objectives:

Pump thrombosis is a serious left ventricular assist device complication, though there are no guidelines regarding its treatment. The main aim of this study was to describe a strategy of intravenous anticoagulation as the initial treatment in these patients and then to compare intravenous heparin with bivalirudin.

Methods:

All consecutive patients who received a HeartWare left ventricular assist device from July 2009 to March 2019 were retrospectively analysed. Patients developing a pump thrombosis were selected, and treatment, outcomes and complications were recorded.

Results:

During this period of time (116 months), 220 patients underwent HeartWare left ventricular assist device implantation and 57 developed pump thrombosis, with an incidence rate of first pump thrombosis of 0.17 events per patient-year of support (incidence rate of all episodes of pump thrombosis: 0.30 events per patient-year of support). All the patients were initially treated medically, predominantly with either intravenous heparin (n = 26) or bivalirudin (n = 16). Patients treated with bivalirudin during the first pump thrombosis episode had less subsequent re-thrombosis episodes (18.7% vs 57.7%, p < 0.05). In addition, percentage time in therapeutic range was greater for bivalirudin compared with heparin (68.5% ± 16.9% vs 37.4% ± 31.0%, p < 0.01). During the first pump thrombosis episode, 26.3% of the patients needed surgery (left ventricular assist device exchange (n = 8), transplant (n = 6) or decommissioning (n = 1)). The overall survival at 1 year was 61.4%, and there was no significant difference in survival.

Conclusion:

Left ventricular assist device thrombosis is a serious life-threatening complication; hence, we propose an initial conservative management of pump thrombosis with enhanced intravenous anticoagulation with either intravenous heparin or bivalirudin, with surgery reserved for refractory cases.

P5418Anticoagulation management of heartware left ventricular assist device thrombosis: comparison of heparin and bivalirudin

Introduction and purpose

Pump thrombosis (PT) is a serious left ventricular assist device (LVAD) complication, though there are no guidelines regarding its treatment. We have adopted a strategy of intravenous anticoagulation as the initial treatment strategy in these patients.

Methods

All consecutive patients who received a HeartWare LVAD from July-2009 to January-2018 were retrospectively analyzed. Patients developing a PT were selected, and treatment, outcomes and complications were recorded.

Results

197 patients underwent HVAD, and 49 developed PT. All the patients were initially treated medically, though during the first PT 26.5% of the patients needed surgery [VAD exchange (n=6), transplant (n=6), or decommissioning (n=1)]. The overall survival at 1 year was 63.3%. Patients were treated predominantly with either intravenous heparin or bivalirudin. There were no significant differences neither in complications nor in survival between the 2 treatments (Figure 1); however, patients treated with bivalirudin during the first PT episode had less subsequent re-thrombosis episodes (18.2% vs 57.7%, p<0.05), and percentage time in therapeutic range was greater for bivalirudin compared with heparin (59.7±4.2 vs 36.3±7.1, p<0.01). Nevertheless, time to normalisation of LDH levels with bivalirudin was longer than with heparin (17.2±2.6 vs 10.2±4.5 days, p<0.01) (Table 1).

Table 1. Comparison of baseline characteristics and outcomes between Heparin and Bivalirudin Heparin (n=26) Bivalirudin (n=11) p-value Male, gender n (%) 20 (76.9) 9 (81.8) 1.00 Age when implant (years) 48±11.8 49.8±11.4 0.67 AF n (%) 9 (34.6) 6 (54.5) 0.50 Diagnosis:   Dilated cardiomyopathy n (%) 13 (50) 7 (63.6)   Ischemic heart disease n (%) 12 (46.2) 3 (27.3)   Congenital heart disease n (%) 1 (3.8) 1 (9) 0.50 Thrombolysis (+ alteplase) n (%) 19 (73.1) 4 (36.4) 0.08 Treatment duration (days) 11.5±7.2 15.3±6.5 0.15 % Time in range 36.3±7.1 59.7±4.2 0.009 Hospitalisation (days) 19.1±16.4 31.9±18.2 0.06 Complications:   Ischemic Stroke n (%) 2 (7.7) 4 (36.4) 0.09   Intracraneal bleeding n (%) 2 (7.7) 0 (0) 0.88   Gastrointestinal bleeding n (%) 1 (3.8) 0 (0) 1.00   Serious bleeding n (%) 5 (19.2) 0 (0) 0.29   Any bleeding n (%) 7 (26.9) 2 (18.2) 0.88 LDH   Baseline 271.7±79.3 221.6±41.3 0.10   Admision 727.8±448.2 517.5±171.3 0.21   Maximum 827.1±424.7 1217.6±1004 0.03   Discharge 334.9±135.9 308.6±111.8 0.70   Time to normalisation (days) 10.2±4.5 17.2±2.6 0.004 Outcomes:   Transplant (total) n (%) 7 (26.9) 2 (18.2) 0.88   VAD Exchange (total) n (%) 8 (30.8) 4 (36.4) 1.00   Mortality at 2 years n (%) 15 (57.7) 5 (45.4) 0.831 Rethrombosis:   Rethrombosis n (%) 15 (57.7) 2 (18.2) 0.03   Number of episodes of rethrombosis 0.15     +1 n=6 n=1     +2 n=4 n=1     +3 n=4 n=0     +4 n=1 n=0

Figure 1

Conclusion

VAD thrombosis is a serious life threatening complication, though an initial strategy with enhanced intravenous anticoagulation is an acceptable strategy with either intravenous heparin or bivalirudin.

Acknowledgement/Funding

N. Bouzas-Cruz would like to thank the Spanish Society of Cardiology (Sociedad Española de Cardiología), for her research grant and fellowship.

P1677Elevation of right-sided pressures and right ventricular echocardiographic parameters: predictors of Exercise Limitation in Patients with Implanted Continuous Flow Left Ventricular Assist Devices

Introduction

Left Ventricular Assist Devices (LVAD) improve survival and functional capacity in patients with advanced heart failure (HF). However, there are potential complications.

Purpose

We sought to determine parameters of exercise intolerance in a group of patients with the HeartWare LVAD (HVAD) compared to a group of HF patients.

Methods

This was a single-centre parallel prospective group-study. Briefly, echocardiograms, right heart catheterisation (RHC) and cardiopulmonary exercise tests were performed in forty-two patients admitted for a heart transplant assessment between August2017 and October2018.Of them 20 belonged to the HVAD group and 22 to the HF group.

Results

In our study, HVAD patients had a better exercise capacity than HF patients, although no significant differences were noted (14.0±5.0 ml/kg/min vs 11.3±3.9 ml/kg/min, p=0.06). To determine exercise tolerance, both HVAD and HF groups were subdivided into 2 groups based on the median peak exercise oxygen consumption (peakVO2) for that group. The table shows the comparison between preserved and non-preserved exercise tolerance in HF and HVADpatients. First of all, in the HVADgroup, all resting RHC pressures were significantly lower in the preserved exercise capacity group. However, in HFpatients there were no statistically significant differences between both subgroups in right-sided pressures, but Thermodilution exercise-induced change in cardiac output (ΔCO) and cardiac index (ΔCI) was significantly higher in the patients with preserved exercise tolerance. Secondly, in the HVADgroup the right ventricle was significantly larger in the reduced exercise tolerance subgroup. Moreover, patients with lower peak VO2 had more significant tricuspid regurgitation. Nevertheless, in HFpatients none of the echocardiographic parameters were related to the exercise capacity.

HF HVAD > Median Peak V02 < Median Peak V02 p > Median Peak V02 < Median Peak V02 p Thermodilution CO, l/min: • Rest 4.3±1.0 4.4±1.8 0.82 4.8±0.8 4.2±1.2 0.21 • Exercise 5.6±1.7 4.8±1.8 0.36 7.1±3.2 4.8±0.8 0.05 • ΔCO 1.26±1.0 0.26±0.7 0.02 2.2±2.5 0.4±0.7 0.05 Right Atrium pressure, mmHg 7.0±4.5 6.8±4.10 0.92 4.3±3.2 10.6±6.40 0.02 Mean Pulmonary Artery pressure, mmHg 26.4±12.6 26.5±10.9 0.97 16.8±5.4 30.5±12.5 0.01 Tricuspid Regurgitation, n (%): • None 1 (9) 1 (9) 1 (12) 0 (0) • Mild 7 (64) 8 (73) 7 (88) 4 (44) • Moderate 2 (18) 0 (0) 0 (0) 4 (44) • Severe 1 (9) 2 (18) 0.36 0 (0) 1 (12) 0.03 Right Ventricle Basal Diastolic Diameter, cm 4.0±1.0 4.1±1.0 0.83 3.7±0.5 4.4±0.5 0.02

Conclusion

Right-sided parameters in the echocardiogram and RHC pressures discriminate between preserved and non-preserved exercise capacity in HVADpatients, but not in HFpatients. In these last patients only ΔCO and ΔCI were statistically correlated with peak exercise oxygen consumption

Acknowledgement/Funding

N. Bouzas-Cruz would like to thank the Spanish Society of Cardiology (Sociedad Española de Cardiología), for her research grant and fellowship

Fast elemental screening of soil and sediment profiles using small-spot energy-dispersive X-ray fluorescence: application to mining sediments geochemistry

Elemental analysis of different sediment cores originating from the Cartagena-La Union mining district in Spain was carried out by means of a programmable small-spot energy-dispersive X-ray fluorescence (EDXRF) spectrometer to study the distribution of heavy metals along soil profiles. Cores were obtained from upstream sediments of a mining creek, from the lowland sedimentation plain, and from a mining landfill dump (tailings pile). A programmable two-dimensional (2D) stage and a focal spot resolution of 600 μm allow us to obtain complete core mapping. Geochemical results were verified using a more powerful wavelength-dispersion X-ray fluorescence (WDXRF) technique. The data obtained was processed in order to study the statistical correlations within the elemental compositions. The results obtained allow us to observe the differential in-depth distribution of heavy metals among the sampled zones. Dump site cores exhibit a homogeneous distribution of heavy metals, whereas the alluvial plain core shows accumulation of heavy metals in the upper part. This approach can be useful for the fast screening of heavy metals in depositional environments around mining sites.

Analysis of lead content in automotive shredder residue (ASR)

Automotive shredder residue (ASR) is a very heterogeneous waste, which could have a very high metal content on finest fractions phi<6 mm produced by the shredding of end of live vehicles. The approval of Directive 2000/53/EC and its transposition to the European Union member states requires an analytical technique for in-situ checking of the content of some metals in ASR wastes. The objective of this study is the evaluation of total Pb content in the different fractions using a rapid measurement method to easily accomplish the current legislation. An experimental Energy Dispersive X-ray Fluorescence (EDXRF) spectrometer with tri-axial geometry was used to analyse the ASR in order to test the feasibility of this analytical technique. Likewise, a correction of the intensities by the incoherent scattering (Compton) radiation was made to compensate the matrix effects. The results show that values in the smaller fractions are bigger (11,600 mg kg(-1) in the fraction <125 microm) than in the coarser fractions (4600 mg kg(-1) in the fraction between 2 and 6 mm) and that such type of instrumentation enables a fast measurement with a limit of detection of 1.1 mg kg(-1) for 1000 s measurement).

Heavy metals' content of automotive shredder residues (ASR): evaluation of environmental risk

Every year between 8 and 9 millions of vehicles in the European Union arrive to their end of life. Car wastes can have a very high metal content, falling into hazardous waste class. A preliminary evaluation of these wastes could be made by metals' leaching test runs which is the main objective of the present study. Evaluation of the total metal content was carried out by X-ray fluorescence and the mobility of these metals using two simple standardized extractions such as the TCLP (Toxicity Characterisation Leaching Procedure) of the US EPA and the German leaching test DIN 38414-S4. Additionally, an extraction test with acetone was performed in order to recognise metals bounded to organic matter. The results show that the total metal content of the ASR can overpass the established values for inert residues. Lead and zinc contents are fairly well correlated with grain-size, whilst other metals' contents do not exhibit clear grain-size dependence.