Catheter Ablation for Atrial Fibrillation-Influence of Modifiable Risk Factors and Ablation Modality on Procedural Efficacy and Safety.

BACKGROUND: Modifiable lifestyle risk factors, in particular obesity and related conditions, are important drivers of atrial fibrillation (AF), impacting the severity of symptoms and influence the efficacy and safety of treatment. OBJECTIVE: The study aimed to assess the impact of modifiable lifestyle factors on the effectiveness and safety of AF ablation, and examine the procedural characteristics, efficacy, safety and cost outcomes of cryoballoon vs radiofrequency ablation, in a real-world clinical setting. METHOD: Patients undergoing catheter ablation for AF (June 2017 to December 2020) were included in this retrospective analysis. Efficacy and safety outcomes were obtained from electronic medical records and state-wide databases. The primary outcome was successful isolation of the pulmonary veins and freedom from AF without repeat ablation or ongoing antiarrhythmic therapy at 12 months. RESULTS: The study included 141 patients (mean age 60±11 years, 57% male). The average body mass index (BMI) was 29.2±5.6 kg/m2. Ablation by cryoballoon was undertaken in 59% (radiofrequency 41%). Acutely successful pulmonary vein isolation was achieved in 92%, however, only 52% (n=74) met the primary outcome (successful isolation of the pulmonary veins and freedom from AF without repeat ablation or ongoing antiarrhythmic therapy) at 12 months. Successful management of AF was more likely in patients with lower BMI (p=0.006; particularly with BMI <27 kg/m2; p=0.004) and weight (p=0.003), and in those without obstructive sleep apnoea (p=0.032). The only independent predictor of the primary outcome was BMI (ß=0.25, p=0.004). Over 75% of complications occurred in those with BMI ≥27 kg/m2. CONCLUSIONS: Catheter ablation for AF is more likely to be unsuccessful in patients with uncontrolled risk factors, particularly obesity. Risk factor optimisation may improve procedural success and reduce the risk of procedural complications.

Spontaneous coronary artery dissection, fibromuscular dysplasia, and biventricular stress cardiomyopathy: a case report.

Background: Spontaneous coronary artery dissection (SCAD) is an important cause of acute coronary syndrome and is associated with fibromuscular dysplasia (FMD). The diagnosis of stress cardiomyopathy in patients with SCAD and FMD is uncommon, though an important consideration given the shared risk profile. Complications of severe left ventricular (LV) dysfunction associated with stress cardiomyopathy, such as LV thrombus, complicate the management of SCAD where anticoagulation is controversial in the context of SCAD-associated intramural haematoma. Case summary: A 65-year-old female presented with non-ST elevation myocardial infarction with a recent diagnosis of hypertension but no other traditional cardiovascular risk factors. There was, however, a family history of early cardiac death from myocardial infarction affecting her mother. Echocardiography demonstrated severe biventricular dysfunction with circumferential akinesis of the mid to apical segments. Coronary angiography demonstrated type 2A SCAD involving the first diagonal artery. Cardiac magnetic resonance imaging (MRI) confirmed a diagnosis of stress cardiomyopathy with biventricular involvement, complicated by LV apical thrombus and a focal region of myocardial infarction. Vascular imaging confirmed the presence of FMD. Guideline-directed heart failure therapy in addition to clopidogrel and rivaroxaban was prescribed. Follow-up contrast echocardiography at six-weeks confirmed resolution of LV dysfunction and resolution of the LV thrombus with no adverse events. Discussion: The dual diagnosis of SCAD and stress cardiomyopathy is uncommon. Cardiac MRI was useful for confirming the diagnosis of stress cardiomyopathy and the presence of LV thrombus, where anticoagulation may complicate the management of intramural haematoma in patients with concomitant SCAD and FMD.

Infective Endocarditis: A Contemporary Study of Microbiology, Echocardiography and Associated Clinical Outcomes at a Major Tertiary Referral Centre.

BACKGROUND: The epidemiology of infective endocarditis (IE) continues to evolve, with antimicrobial resistance and clinical outcomes largely dependent on the environment of acquisition. This study aimed to provide a contemporary review of the microbiology and antimicrobial management of IE and report echocardiographic findings and predictors of adverse outcomes in community-acquired and health care-associated IE. METHODS: Consecutive presentations of IE to a major Australian tertiary referral centre between January 2011 and April 2016 were examined. Culprit organisms and resistance patterns were recorded, as was transthoracic and transoesophageal echocardiography. Real-world antimicrobial prescription and use of an outpatient parenteral antimicrobial therapy (OPAT) service were also assessed, and clinical outcomes analysed. RESULTS: Of 204 consecutive cases, 30% were associated with health care, a group with a higher burden of comorbidities and more prone to complications. Health care-associated cases had lower rates of surgical intervention but higher mortality. A history of intravenous drug use (IVDU) conferred risk for recurrent IE whereas multivalvular involvement predicted heart failure hospitalisation. Staphylococcus aureus was isolated in 45%. Whilst methicillin resistance remains low, the prevalence of S. aureus IE is increasing. Single antimicrobial agents were commonly used (83%) and therapy via OPAT was safe and significantly reduced length of hospital stay. Not undergoing transoesophageal echocardiography (TOE) or definitive surgical management conferred poorer prognosis. CONCLUSIONS: The epidemiology of IE is evolving and there is need for updated epidemiological data and associated clinical outcomes. Environment of acquisition remains important in the face of increasing health care provision and the changing predominance of culprit microorganisms.

Socioeconomic factors correlating with community antimicrobial prescribing.

BACKGROUND: Increasing antimicrobial resistance is a serious concern in New Zealand and worldwide. Antimicrobial resistance is tied to increased community antimicrobial consumption. Investigation of the drivers of antimicrobial prescribing in different locales is needed so that targeted interventions can be devised. Counties Manukau District Health Board (CMDHB) serves a diverse, relatively socio-economically deprived population that has the highest rate of community antimicrobial prescribing in New Zealand. We hypothesise that socio-economic factors are important in determining much of the prescribing of antimicrobials in the CMDHB population. METHODS: We collected data on the number of antibacterial prescriptions per person in each pre-defined geographical Area Unit in the CMDHB community in 2013, and compared these with demographic and socioeconomic parameters collected in the 2013 New Zealand census. Simple and multiple linear regression analyses were used to identify factors that correlated with antimicrobial prescribing. RESULTS: Multiple regression analysis showed that antimicrobial prescribing was strongly associated with a higher ratio of number of people to bedrooms in a dwelling (an index of crowding), with some added association with Maori ethnicity. When these factors were accounted for, there was no significant added influence from a range of other factors such as income, smoking or educational qualifications. CONCLUSIONS: Antimicrobial prescribing may be influenced by different factors within different communities. It is important to target the determinants of antimicrobial prescribing when addressing the issue of high community antimicrobial consumption. In the CMDHB community, crowding in homes is associated with higher rates of antimicrobial prescribing. This association may be because crowding directly increases infection rates, or that crowding serves as a proxy for other factors yet to be identified. Further investigation of the determinants of antimicrobial prescribing is needed.

Influence of altered blood rheology on ventricular-vascular response to exercise.

Blood (or plasma) rheology is related to cardiovascular risk. Mechanisms of this association are unclear but may be partially related to impaired left ventricular (LV) function and increased central blood pressure (BP) during light activity. This study aimed to test these hypotheses. Twenty patients (14 men; aged 61+/-12 years) with polycythemia rubra vera (n=16) or hemochromatosis (n=4) were studied at rest and during exercise at approximately 50% of maximal heart rate before and after venesection (500 mL; volume replaced with saline) to elicit an acute decrease in plasma viscosity at stable BP. Controls (n=20) underwent the same protocol with 25-mL venesection. Central BP and augmentation index were determined by tonometry. Resting LV systolic (peak longitudinal systolic strain rate and strain) and diastolic functions were determined by tissue-Doppler echocardiography. Venesection with blood volume replacement decreased viscosity (1.46+/-0.10 to 1.41+/-0.11 centipoise), protein, and hemoglobin (P<0.05 for all) and increased strain rate and strain (P<0.001 for both) in patients but not in controls (P>0.10 for all). There was no change in LV diastolic function (P>0.12 for all). Exercise augmentation index in patients was reduced after venesection (24+/-12% to 17+/-9%; P=0.001) despite no significant change in other BP variables. Hemodynamics (resting or exercise) were not significantly changed in controls. Exercise central systolic BP correlated with triglycerides (r=0.59; P<0.001). However, neither exercise hemodynamic changes nor LV functional changes correlated with any biochemical changes after venesection (P>0.05). We conclude that an acute change in blood rheology improves ventricular-vascular interaction by enhanced LV systolic function and reduced light-exercise central BP.

Clinical presentation, etiology, and outcome of infective endocarditis in the 21st century: the International Collaboration on Endocarditis-Prospective Cohort Study.

BACKGROUND: We sought to provide a contemporary picture of the presentation, etiology, and outcome of infective endocarditis (IE) in a large patient cohort from multiple locations worldwide. METHODS: Prospective cohort study of 2781 adults with definite IE who were admitted to 58 hospitals in 25 countries from June 1, 2000, through September 1, 2005. RESULTS: The median age of the cohort was 57.9 (interquartile range, 43.2-71.8) years, and 72.1% had native valve IE. Most patients (77.0%) presented early in the disease (<30 days) with few of the classic clinical hallmarks of IE. Recent health care exposure was found in one-quarter of patients. Staphylococcus aureus was the most common pathogen (31.2%). The mitral (41.1%) and aortic (37.6%) valves were infected most commonly. The following complications were common: stroke (16.9%), embolization other than stroke (22.6%), heart failure (32.3%), and intracardiac abscess (14.4%). Surgical therapy was common (48.2%), and in-hospital mortality remained high (17.7%). Prosthetic valve involvement (odds ratio, 1.47; 95% confidence interval, 1.13-1.90), increasing age (1.30; 1.17-1.46 per 10-year interval), pulmonary edema (1.79; 1.39-2.30), S aureus infection (1.54; 1.14-2.08), coagulase-negative staphylococcal infection (1.50; 1.07-2.10), mitral valve vegetation (1.34; 1.06-1.68), and paravalvular complications (2.25; 1.64-3.09) were associated with an increased risk of in-hospital death, whereas viridans streptococcal infection (0.52; 0.33-0.81) and surgery (0.61; 0.44-0.83) were associated with a decreased risk. CONCLUSIONS: In the early 21st century, IE is more often an acute disease, characterized by a high rate of S aureus infection. Mortality remains relatively high.

First case of Mycobacterium heckeshornense lymphadenitis.

Mycobacterium heckeshornense is a slow-growing nontuberculous mycobacterium first characterized in 2000. It is reported to cause lung disease and tenosynovitis. We report a case of isolated massive axillary lymphadenopathy in an elderly woman, where histology showed necrotizing granulomata and M. heckeshornense was isolated as the causative organism.

A clinicopathological review of 34 cases of inflammatory breast disease showing an association between corynebacteria infection and granulomatous mastitis.

AIM: Granulomatous mastitis is a rare condition of unknown aetiology. The great majority of cases has not been associated with bacterial pathogens if women with mammary tuberculosis are excluded. We noted that some women in Auckland with a histological diagnosis of granulomatous mastitis had both microbiological and histological evidence of corynebacteria infection and aimed to study this further. METHODS: Thirty-four women were reviewed who presented with inflammatory breast disease and had microbiological specimens from which corynebacteria were isolated and/or histological specimens containing coryneform bacteria. These 34 cases were compared with 28 controls with similar histology but no evidence of corynebacteria infection. RESULTS: Twenty-seven (79%) of the cases and 21 (75%) of the controls had histological and/or cytological evidence of suppurative granulomas. Fourteen of the 34 cases also had Gram-positive bacilli (GPB), recognisable as coryneform bacteria, in histological sections. In all cases the bacilli were confined to empty spaces, consistent with dissolved lipid, and were surrounded by neutrophils and, frequently, suppurative granulomas. Corynebacterium species were isolated from 52 of 116 microbiological specimens taken from the 34 cases. Forty of these 52 cultures were pure. Twenty-four of the cultures were further classified biochemically and using 16S rRNA gene sequencing. Twenty of the 24 were lipophilic Corynebacterium species and 14 were identified as Corynebacterium kroppenstedtii. The cases were more likely to present with fever or neutrophilia and more often formed sinuses than the controls but other clinical features were similar. Maori and Pacific Islanders accounted for 77% of the women across both groups. CONCLUSION: We suggest granulomatous mastitis can be associated with corynebacteria infection, particularly infection by C. kroppenstedtii. The significance of this finding, which has previously been described in only a single case report, is discussed.

Herpes simplex virus tegument protein US11 interacts with conventional kinesin heavy chain.

Little is known about the mechanisms of transport of neurotropic herpesviruses, such as herpes simplex virus (HSV), varicella-zoster virus, and pseudorabies virus, within neurons. For these viruses, which replicate in the nucleus, anterograde transport from the cell body of dorsal root ganglion (DRG) neurons to the axon terminus occurs over long distances. In the case of HSV, unenveloped nucleocapsids in human DRG neurons cocultured with autologous skin were observed by immunoelectron microscopy to colocalize with conventional ubiquitous kinesin, a microtubule-dependent motor protein, in the cell body and axon during anterograde axonal transport. Subsequently, four candidate kinesin-binding structural HSV proteins were identified (VP5, VP16, VP22, and US11) using oligohistidine-tagged human ubiquitous kinesin heavy chain (uKHC) as bait. Of these viral proteins, a direct interaction between uKHC and US11 was identified. In vitro studies identified residues 867 to 894 as the US11-binding site in uKHC located within the proposed heptad repeat cargo-binding domain of uKHC. In addition, the uKHC-binding site in US11 maps to the C-terminal RNA-binding domain. US11 is consistently cotransported with kinetics similar to those of the capsid protein VP5 into the axons of dissociated rat neurons, unlike the other tegument proteins VP16 and VP22. These observations suggest a major role for the uKHC-US11 interaction in anterograde transport of unenveloped HSV nucleocapsids in axons.