Characterization of atrial lesion safety and efficacy utilizing a circular catheter and the IRE generator with an in vivo porcine model

Funding Acknowledgements

Type of funding sources: Other. Main funding source(s): Biosense Webster, Inc.

Introduction/Objectives:

Pulsed field ablation (PFA) is a non-thermal ablative method that delivers high voltage, very-short duration pulses that cause pore formation in the cytoplasmic membrane and cell death. The tissue selectivity of PFA is expected to reduce the risk of collateral tissue injury compared to radiofrequency catheter ablation (RFCA), while maintaining effectiveness.  The objective of this study was to perform pulmonary vein (PV) isolation in a porcine model to characterize the safety and performance of a novel, fully-integrated biphasic PFA system. The system is comprised of a multi-channel generator, a variable loop circular catheter, and an integrated irreversible electroporation (IRE) mapping software module.

Methods

The study evaluated safety and efficacy of IRE in 8 healthy swine. First, to evaluate safety, multiple ablations were performed at various cardiac structures, including within the lumen of the right pulmonary vein (RIPV), at the right superior pulmonary vein (RSPV) ostium, and adjacent to the esophagus. Second, to evaluate efficacy, animals were recovered and followed for 30 (±3) days, then re-mapped. Gross pathological and histopathological examinations were performed to assess for procedural injury, chronic thrombosis, tissue ablation, depth of penetration, healing, and level of inflammatory response.

Results

All 8 swine survived for the 30 (±3) day follow up (FU) period. There were no acute (day of procedure) incidents of pulmonary vein narrowing of >70%, nor at 30 d follow-up (FU), even when ablation was purposefully performed directly deep to the ostium of the vein. No injury was seen grossly or histologically in the adjacent esophagus. All PVs were durably isolated as confirmed by bidirectional block at the 30 (±3) day re-map procedure, and histological examination showed complete, transmural necrosis around the entire circumference of the ablated section of the right PVs [Figure].

Conclusion(s): This pre-clinical evaluation of a fully integrated PFA system demonstrated effective and durable ablation of cardiac tissue and PV isolation with no collateral damage to adjacent structures. Notably, histological staining confirmed complete transmural cell necrosis around the circumference of the ostial PV at 30 days. Abstract Figure. PVI maps (A) histology (B) and safety(C)

The effect of the COVID-19 pandemic on time to angiography and outcomes in patients presenting with non-ST elevation myocardial infarction

Funding Acknowledgements

Type of funding sources: None.

Background

Covid-19 pandemic has had a profound impact on healthcare service delivery. Acute cardiovascular care however remains a priority despite the pandemic. Patients presenting with non-ST elevation MI (NSTEMI) have been poorly characterised during the pandemic.

Methods

We conducted a retrospective study of patients diagnosed with NSTEMI during the peak of the pandemic between April-May 2020 at our tertiary centre in the UK. Data was collected from electronic patient clinical records including time from admission to angiography, length of stay, mortality, prescription of secondary prevention pharmacotherapy and referral to cardiac rehabilitation. We compared this data to the same time period in 2019.

Results

As can be seen from Table 1, in 2020, the mean age, median time to angiography and length of stay were all significantly lower than the control period of 2019. Prescription of secondary prevention medication (Aspirin, P2Y12 inhibitor, Beta-blocker, Statin and ACEi/ARB) and referral to cardiac rehabilitation also improved in 2020, however neither was statistically significant.

During the 2020 period, 1 patient died due to late presentation NSTEMI and multi-organ failure. There were 3 deaths in 2019: complications following coronary bypass surgery, upper GI bleed and a subarachnoid haemorrhage.

Conclusion

Our results show that the mean age of the patients presenting with NSTEMI during the peak of Covid-19 pandemic was younger suggesting that elderly patients failed to present. Compared to 2019, there was significant improvement in patient treatment times with a significantly shorter stay in hospital, probably as a result of the reduction in elective activity allowing un-restrained access to the catheter labs.  We also saw improvement in prescription for secondary prevention and referral to cardiac rehabilitation services during this time suggesting that there may have been improved focus on these aspects of care again.

Left ventricular function and clinical heart failure after myocardial infarction revascularized with percutaneous coronary intervention - comparison between STEMI and NSTEMI in modern practice

Funding Acknowledgements

Type of funding sources: None.

Introduction

Left ventricular systolic dysfunction (LVSD) is a common consequence of myocardial infarction (MI). Data from historic series identified LVSD in up to 60% of patients post-MI. However, in modern practice, with high-sensitivity cardiac biomarkers leading to early detection of MI and widespread use of early revascularization, the prevalence of LVSD in the acute phase of MI and its impact on subsequent clinical heart failure remains unknown.

Purpose

To ascertain the prevalence of LVSD on pre-discharge echocardiography and its impact on subsequent clinical heart failure after type 1 MI treated with percutaneous coronary intervention (PCI) in a UK tertiary cardiac centre.

Methods

A retrospective electronic patient records review of consecutive patients with type 1 MI treated with PCI between January 2016 - December 2017. Patients treated conservatively or with surgical revascularization were excluded.

Results

1000 consecutive patients were identified and 948/1000 who had an inpatient echocardiogram prior to discharge were included in this analysis – 413 ST elevation MI (STEMI) and 535 non-ST elevation (NSTEMI). Median door to balloon time for STEMI was 42 minutes (IQR 28-79). Median time from symptom onset to intervention for NSTEMI was 3 days (IQR 1-6). LVSD was defined as left ventricular ejection fraction (LVEF) <50% on transthoracic echocardiogram carried out during the hospital episode. LVSD was significantly more prevalent in patients with STEMI compared to NSTEMI (37.4% vs 17.3%, p < 0.001). Median LVEF was significantly lower in the STEMI population (55%, IQR 45-60) compared to patients with NSTEMI (60%, IQR 54-65), p < 0.001. However, rates of clinical heart failure at index presentation with MI did not vary significantly between STEMI and NSTEMI patients (6.1% vs 4.9%, p = 0.414). In stepwise multivariate regression models: age, peak troponin and previous coronary artery bypass grafting were predictors of LVEF, whereas LVEF and previous MI were predictors of clinical heart failure

Patients with LVSD on pre-discharge echocardiography had significantly higher rates of 30-day readmission with heart failure (2.9% vs 0.7%, p = 0.017), 30-day all-cause mortality (6.1% vs 2%, p = 0.001), 30-day cardiac mortality (5.7% vs 1%, p < 0.001) and 2-year all-cause mortality (5.7% vs 1.6%, p = 0.001). However, at 2-years, there was no difference in hospital readmission with heart failure (0.8% vs 0.3%, p = 0.276). There were no significant differences between STEMI and NSTEMI patients for these endpoints.

Conclusions

Early revascularisation with PCI has led to a reduction in the prevalence of early LVSD post-MI compared to historical data. However, the presence of LVSD remains a powerful predictor of adverse clinical outcomes. Despite lower rates of LVSD on pre-discharge echocardiography in patients with NSTEMI compared with STEMI, the incidence of subsequent clinical heart failure is similar. This however may be underestimated due to survival bias.

Opposing actions of the synapse-associated protein of 97-kDa molecular weight (SAP97) and Disrupted in Schizophrenia 1 (DISC1) on Wnt/β-catenin signaling

It has been suggested that synapse-associated protein of 97-kDa molecular weight (SAP97) is a susceptibility factor for childhood and adult neuropsychiatric disorders. SAP97 is a scaffolding protein that shares direct and indirect binding partners with the Disrupted in Schizophrenia 1 (DISC1) gene product, a gene with strong association with neuropsychiatric disorders. Here we investigated the possibility that these two proteins converge upon a common molecular pathway. Since DISC1 modifies Wnt/β-catenin signaling via changes in glycogen synthase kinase 3 beta (GSK3β) phosphorylation, we asked if SAP97 impacts Wnt/β-catenin signaling and GSK3β phosphorylation. We find that SAP97 acts as inhibitor of Wnt signaling activity and can suppress the stimulatory effects of DISC1 on β-catenin transcriptional activity. Reductions in SAP97 abundance also decrease GSK3β phosphorylation. In addition, we find that over expression of DISC1 leads to an increase in the abundance of SAP97, by inhibiting its proteasomal degradation. Our findings suggest that SAP97 and DISC1 contribute to maintaining Wnt/β-catenin signaling activity within a homeostatic range by regulating GSK3β phosphorylation.

Pharmacokinetics and pharmacodynamics of rilotumumab: a decade of experience in preclinical and clinical cancer research

Rilotumumab is a fully human monoclonal antibody against hepatocyte growth factor, the only known ligand of the MET receptor. Over the last decade, rilotumumab has been extensively tested in preclinical studies and in clinical studies in a variety of cancer types. In this review, we examine the pharmacokinetic and pharmacodynamic data that have been collected in the rilotumumab programme to date, and discuss retrospectively how the knowledge acquired in this programme can be applied to a number of key issues in oncology drug development, including: (i) using preclinical data to inform first-in-human study design; (ii) the role of biomarkers in the identification of a target patient population; (iii) the potential for drug interactions between therapeutic proteins and other anticancer agents; and (iv) pharmacokinetic and pharmacodynamic considerations in phase 3 study design.

Romiplostim dose response in patients with immune thrombocytopenia

A pharmacodynamic model was developed for platelet counts in 52 patients with immune thrombocytopenia (ITP) receiving subcutaneous romiplostim in 3 phase I/II studies (dose range, 0.2-10 µg/kg). The model consisted of a drug-sensitive progenitor cell compartment linked to a peripheral blood compartment through 4 transition compartments. The baseline platelet count, mean transit time, and kinetics of drug effect constant were 11.1 × 10(9)/L, 170 hours, and 0.6 day(-1), respectively. The ITP patients had a shorter platelet life span and lower progenitor cell production rates than healthy volunteers. Romiplostim response was described for 2 subpopulations. The romiplostim stimulatory effect in ITP patients was 351%/100 µg/wk and 12%/100 µg/wk in 68% and 32% of patients, respectively. Visual and numerical predictive checks suggested accurate prediction of platelet time course and durable response rate in ITP patients. Model-based simulations confirmed the effectiveness of dose reduction to prevent platelet counts >400 × 10(9)/L.

Changes in weight and metabolic parameters during treatment with antipsychotics and metformin: do the data inform as to potential guideline development? A systematic review of clinical studies

BACKGROUND

Changes in weight and metabolic parameters have been commonly reported in patients with schizophrenia. Metformin has been evaluated in clinical studies to prevent or reduce weight gain and changes in metabolic parameters in non-diabetic subjects. We undertook a systematic review of the efficacy and safety of metformin in reducing weight gain and metabolic abnormalities in non-diabetic subjects with schizophrenia or bipolar disorder taking antipsychotic medication to establish if these data could potentially drive guideline development.

METHODS

Medical databases were searched using terms including 'antipsychotic', 'atypical antipsychotic agent', 'antipsychotic agents', 'antipsychotic-drug' and 'metformin' and 'weight'. Studies reporting weight and/or metabolic outcomes in non-diabetic subjects with schizophrenia and bipolar disorder were included regardless of methodological type and subject age.

RESULTS

Nine randomised double-blind studies and two open cohort studies evaluating metformin and changes in weight in trials up to 16 weeks were identified. In all, 495 participants received antipsychotics (mostly olanzapine), and three studies were in subjects aged < 18 years. The adult studies predominantly utilised non-Caucasian subjects with chronic schizophrenia. Weight and lifestyle intervention programmes were provided to all cohorts in eight studies, which confounded interpretation of the data. In ten studies, the addition of metformin to antipsychotic treatment was associated with either significantly attenuated weight gain or weight loss compared with control groups. Nine studies measured various glucose parameters. In four studies, subjects prescribed metformin had significantly improved glucose parameters relative to controls. The two studies of metformin in patients with first-episode schizophrenia demonstrated the largest improvement in weight and glucose parameters.

CONCLUSIONS

Metformin may have some value in reducing or preventing weight gain and changes in metabolic parameters during treatment with antipsychotic medication particularly in first-episode psychosis; however, it has been predominantly studied short-term and in non-Caucasian populations. A number of new trials are due to report data 2009-2013 to aid definitive interpretation of the role of metformin. Further longer-term studies are warranted before definitive guidelines can be established.

Pituitary adenylyl cyclase-activating polypeptide stimulates DNA synthesis but delays maturation of oligodendrocyte progenitors

The neuropeptide pituitary adenylyl cyclase-activating peptide (PACAP) and one of its receptors (PAC(1)) are expressed in embryonic neural tube, where they appear to regulate neurogenesis and patterning. We now show that PAC(1) gene expression is also present in neonatal rats in the ventricular and subventricular zones and in the optic chiasm, areas that are rich in oligodendrocyte (OL) progenitors (OLP). Because actions of PACAP on OLP have not been reported, we examined the effects of PACAP on the proliferation of purified OLP in culture and on myelinogenesis in cerebellar slices. Northern analyses on total RNA from purified glial cell subtypes revealed an abundant 7 kb hybridizing transcript in OLP, which was confirmed to correspond to the PAC(1) receptor by reverse transcription-PCR. The presence of this receptor was also corroborated by radioligand binding and cAMP assay. In cultured OL, receptor density decreased during maturation but was partially counterbalanced by the appearance of sites that bound both PACAP and the related peptide vasoactive intestinal peptide. PACAP increased DNA synthesis in OLP cultures almost twofold and increased the bromodeoxyuridine-labeling index in O4-positive OLP. PACAP treatment also resulted in decreased sulfate incorporation into sulfatide in cultures of differentiating OL. The PACAP effect on sulfatide synthesis was fully reproduced in a cerebellar explant model. These findings indicate that PACAP may act at two stages during OL development to (1) stimulate proliferation and (2) delay maturation and/or myelinogenesis.

Coronary artery stenting in unstable angina pectoris: a comparison with stable angina pectoris

OBJECTIVE

To compare early complication rates in unselected cases of coronary artery stenting in patients with stable v unstable angina.

SETTING

Tertiary referral centre.

PATIENTS

390 patients with stable angina pectoris (SAP) and 306 with unstable angina (UAP). Patients treated for acute myocardial infarction (primary angioplasty) or cardiogenic shock were excluded.

INTERVENTIONS

268 coronary stents were attempted in 211 patients (30.3%). Stents used included AVE (63%), Freedom (14%), NIR (7%), Palmaz-Schatz (5%), JO (5%), and Multilink (4%). Intravascular ultrasound was not used in any of the cases. All stented patients were treated with ticlopidine and aspirin together with periprocedural unfractionated heparin.

RESULTS

123 stents were successfully deployed in 99 SAP patients v 132 stents in 103 UAP patients. Failed deployment occurred with nine stents in SAP patients, v four in UAP patients (NS). Stent thrombosis occurred in four SAP patients and 11 UAP patients. Multivariate analysis showed no relation between stent thrombosis and clinical presentation (SAP v UAP), age, sex, target vessel, stent length, or make of stent. Stent thrombosis was associated with small vessel size (p < 0.001) and bailout stenting (p = 0.01) compared with elective stenting and stenting for suboptimal PTCA, with strong trends toward smaller stent diameter (p = 0.052) and number of stents deployed (p = 0.06). Most stent thromboses occurred in vessels < 3 mm diameter.

CONCLUSIONS

Coronary artery stenting in unstable angina is safe in vessels >/= 3 mm diameter, with comparable initial success and stent thrombosis rates to stenting in stable angina.

Coronary pseudo-lesions induced in the left anterior descending and right coronary artery by the angioplasty guide-wire

New lesions appearing during coronary angioplasty may be due to a number of causes including spasm, dissection, embolisation, thrombosis and creation of a pseudo-lesion. The term "coronary pseudo-lesions" has been given to describe artefactual lesions occurring during percutaneous transluminal coronary angioplasty and induced by the angioplasty guide-wire and/or balloon as a result of straightening of the vessel's curvature. No specific treatment is required as they resolve completely on removal of the angioplasty wire. Few modern texts of interventional cardiology contain description of this important phenomenon and we suspect that they pass largely unrecognised. All angioplasty operators should become familiar with this complication as failure to do so may lead to inappropriate intervention with attendant increase in risk to the patient. We report three cases of coronary pseudo-lesion. In two cases affecting the right coronary artery and in the third the left anterior descending coronary artery. Pseudo-lesions affecting the right coronary artery have been previously reported in the literature however pseudo-lesion affecting the left anterior descending artery has not been described. The possible mechanisms of this phenomenon and its management are discussed.

Massive intrapericardial lipoma, a rare cause of breathlessness. Investigations and management

Massive intrapericardial lipoma is a rare cause of breathlessness. We describe a case, review the literature and discuss the presentation, investigation and management of this disorder.

Whole-blood test for total cholesterol by a self-metering, self-timing disposable device with built-in quality control

A whole-blood test for total cholesterol has been developed that is performed in a low-cost disposable flow device without user intervention (after sample addition). The device meters the sample, separates plasma from erythrocytes, and precisely times plasma flow into various reagent compartments, including a quality-assurance chamber. Test results are displayed as a well-defined and easily readable color bar. A quality-control window attests to the integrity of the test components. Here, we describe the assembly and individual functions of the device and report its performance characteristics. Precision and accuracy studies in four clinical studies at independent locations yielded total imprecision of <5% and an average bias of 1.35% vs the Abell-Kendall method.

Adaptation to spatial offsets

After prolonged viewing of a three-element target in which the middle element is spatially offset, subsequent viewing of the same three elements in alignment results in the middle element appearing to be offset in the opposite direction. This adaptational aftereffect to a spatial offset was investigated with elements which were spatial-frequency narrowband and equidetectable to ascertain (a) the properties of the mechanisms involved and (b) the nature of the underlying computation. Evidence is presented in favour of an orientational-grouping, rather than a purely positional computation, underlying this aftereffect. A dual site of adaptation is proposed: one which receives input from the orientation extracted from the output of linear filters, and another which receives input from the orientation derived from grouping processes working on the contrast-energy representation. These may correspond to the mechanisms which are thought to underlie the processing of real and subjective contours.

Single-stage management of cholesteatoma

Surgical management of chronic otitis media with cholesteatoma can be performed in a single-stage procedure, with revision surgery necessary because of recurrent disease or electively with unsatisfactory hearing results. We retrospectively reviewed 164 cases with cholesteatoma surgically managed from 1980 through 1986. In total there were 11 tympanoplasties, 36 canal wall-up mastoidectomies, 81 canal wall down modified radical mastoidectomies, and 36 radical mastoidectomies. The recidivistic rate for cholesteatoma in patients available for 5-year followup was 11% for tympanoplasties, 19% for canal wall-up mastoidectomies, 5% for canal wall-down modified radical mastoidectomies, and 0% for radical mastoidectomies. Hearing results were best in patients who required tympanoplasty alone, followed by those who underwent canal wall-down procedures. Single-stage management of cholesteatoma with modified radical mastoidectomy (canal wall-down) required fewer revisions for recidivistic cholesteatoma and achieved better hearing results than canal wall-up procedures. We conclude, therefore, that staging is not necessary. Improved hearing may likely be achieved with a second procedure, but this is at the patient's discretion.

Pneumocystis carinii infection presenting as necrotizing thyroiditis and hypothyroidism

Extrapulmonary Pneumocystis infection has been increasingly reported in patients with acquired immune deficiency syndrome (AIDS), in particular, recently in association with the increasing use of aerosolized pentamidine. This report describes the unusual presentation of extrapulmonary Pneumocystis infection as a thyroid neck mass and clinical hypothyroidism in a 37-year-old man with hemophilia and AIDS. This case differs from the previously reported single case of isolated thyroid pneumocystosis in the presence of a rapidly enlarging neck mass, lack of previous Pneumocystis, and prior prophylaxis with aerosolized pentamidine. The pathologic and electron microscopic description of the peculiar flocculent necrotic thyroid material is contrasted with typical pulmonary alveolar findings in Pneumocystis pneumonia (PCP), the differential diagnoses of a rapidly expanding neck mass, and diagnostic difficulties of hypothyroidism in patients with AIDS are discussed. Finally, it is emphasized that use of aerosolized pentamidine, although successful for prevention of pulmonary PCP, may be insufficient to prevent extrapulmonary infection.