Transvenous versus subcutaneous implantable cardioverter defibrillators in young cardiac arrest survivors.

Secondary prevention implantable cardioverter defibrillators (ICDs) are indicated in young patients presenting with aborted sudden cardiac death (SCD) because of ventricular arrhythmias. Transvenous-ICDs (TV-ICDs) are effective, established therapies supported by evidence. The significant morbidity associated with transvenous leads led to the development of the newer subcutaneous-ICD (S-ICD). This review discusses the clinical considerations when selecting an ICD for the young patient presenting with out-of-hospital cardiac arrest. The major benefits of TV-ICDs are their ability to pace (antitachycardia pacing [ATP], bradycardia support and cardiac resynchronisation therapy [CRT]) and the robust evidence base supporting their use. Other benefits include a longer battery life. Significant complications associated with transvenous leads include pneumothorax and tamponade during insertion and infection and lead failure in the long term. Comparatively, S-ICDs, by virtue of having no intravascular leads, prevent these complications. S-ICDs have been associated with a higher incidence of inappropriate shocks. Patients with an indication for bradycardia pacing, CRT or ATP (documented ventricular tachycardia) are seen as unsuitable for a S-ICD. If venous access is unsuitable or undesirable, S-ICDs should be considered given the patient is appropriately screened. There is a need for further randomised controlled trials to directly compare the two devices. TV-ICDs are an effective therapy for preventing SCD limited by significant lead-related complications. S-ICDs are an important development hindered largely by an inability to pace. Young patients stand to gain the most from a S-ICD as the cumulative risk of lead-related complications is high. A clinical framework to aid decision-making is presented.

Subcutaneous defibrillator use with unipolar pacemakers: Cautiously possible.

Implantation of subcutaneous implantable cardioverter-defibrillator in a patient with existing unipolar pacemaker is against manufacturer recommendations. We report the case of a successful subcutaneous implantable cardioverter-defibrillator implantation in a patient with Fontan circulation and concomitant active unipolar pacing and present a summary of recommendations when considering subcutaneous implantable cardioverter-defibrillator implantation with unipolar pacing. Recommendations included: pre-procedure screening, rescreening during implantation and ventricular fibrillation induction, pacemaker programming, and post-procedure investigations.

Prescription trends and costs of diabetes medications in Australia between 2003 and 2019: an analysis and review of the literature.

BACKGROUND: Since the turn of the century, the prevalence of diabetes mellitus in Australia has increased, primarily due to rising rates of Type 2 diabetes. Simultaneously, the landscape of diabetes medications has evolved significantly. The change in prescribing trends and public spending on diabetes medications within Australia during this period are not well defined. AIMS: To establish the frequency and cost of dispensed diabetes medications in the Australian public healthcare system between 2003 and 2019. METHODS: We performed a longitudinal nationwide observational study using data obtained from the Pharmaceutical Benefits Scheme (PBS) and Medicare Benefits Schedule websites, which contain information on frequency and spending of diabetes medications dispensed in Australia. RESULTS: The total number of PBS-subsidised prescriptions dispensed for diabetes increased from 5 218 690 in 2003 to 12 188 568 in 2019, and spending increased from $117 241 031 to $598 904 983. Of the non-insulin agents, metformin was consistently the most frequently dispensed agent, with a rapid growth in metformin combination tablets. Dispensation of sulphonylureas and thiazolidinediones have declined, with a simultaneous increase in dipeptidyl peptidase-4 inhibitors, sodium-glucose co-transporter 2 inhibitors and glucagon-like peptide-1 receptor agonists. CONCLUSIONS: Our data show a large growth in the use of diabetes medications between 2003 and 2019. The rapid growth in dispensing of drugs with proven cardiovascular and renal benefits reflect the evolving approach of diabetes treatment, from a historical approach targeting glycaemic control alone, to a modern individualised approach targeting specific co-morbidities.

Impact of device length on electrogram sensing in miniaturized insertable cardiac monitors.

BACKGROUND: Little data exists on electrogram sensing in current generation of miniaturized insertable cardiac monitors (ICMs). OBJECTIVE: To compare the sensing capability of ICM with different vector length: Medtronic Reveal LINQ (~40 mm) vs. Biotronik Biomonitor III (BM-III, ~70 mm). METHODS: De-identified remote monitoring transmissions from n = 40 patients with BM-III were compared with n = 80 gender and body mass index (BMI)-matched patients with Reveal LINQ. Digital measurement of P- and R-wave amplitude from calibrated ICM electrograms was undertaken by 3 investigators independently. Further, we evaluated the impact of BMI and gender on P-wave visibility. RESULTS: Patients in both groups were well matched for gender and BMI (53% male, mean BMI 26.7 kg/m2, both p = NS). Median P- and R-wave amplitude were 97% & 56% larger in the BM-III vs. LINQ [0.065 (IQR 0.039-0.10) vs. 0.033 (IQR 0.022-0.050) mV, p < .0001; & 0.78 (IQR 0.52-1.10) vs. 0.50 (IQR 0.41-0.89) mV, p = .012 respectively). The P/R-wave ratio was 36% greater with the BM-III (p < .001). The 25th percentile of P-wave amplitude for all 120 patients was .026 mV. Logistic regression analysis showed BM-III was more likely than LINQ to have P-wave amplitude ≥.026 mV (OR 7.47, 95%CI 1.965-29.42, p = .003), and increasing BMI was negatively associated with P-wave amplitude ≥.026 mV (OR 0.84, 95%CI 0.75-0.95, p = .004). However, gender was not significantly associated with P-wave amplitude ≥.026 mV (p = .37). CONCLUSION: The longer ICM sensing vector of BM-III yielded larger overall P- and R- wave amplitude than LINQ. Both longer sensing vector and lower BMI were independently associated with greater P-wave visibility.

Long-Term Implications of Pacemaker Insertion in Younger Adults: A Single Centre Experience.

BACKGROUND: The long-term implications of pacemaker insertion in younger adults are poorly described in the literature. METHODS: We performed a retrospective analysis of consecutive younger adult patients (18-50 yrs) undergoing pacemaker implantation at a quaternary hospital between 1986-2020. Defibrillators and cardiac resynchronisation therapy devices were excluded. All clinical records, pacemaker checks and echocardiograms were reviewed. RESULTS: Eighty-one (81) patients (median age 41.0 yrs IQR=35-47.0, 53% male) underwent pacemaker implantation. Indications were complete heart block (41%), sinus node dysfunction (33%), high grade AV block (11%) and tachycardia-bradycardia syndrome (7%). During a median 7.9 (IQR=1.1-14.9) years follow-up, nine patients (11%) developed 13 late device-related complications (generator or lead malfunction requiring reoperation [n=11], device infection [n=1] and pocket revision [n=1]). Five (5) of these patients were <40 years old at time of pacemaker insertion. At long-term follow-up, a further nine patients (11%) experienced pacemaker-related morbidity from inadequate lead performance managed with device reprogramming. Sustained ventricular tachycardia was detected in two patients (2%). Deterioration in ventricular function (LVEF decline >10%) was observed in 14 patients (17%) and seven of these patients required subsequent biventricular upgrade. Furthermore, four patients (5%) developed new tricuspid regurgitation (>moderate-severe). Of 69 patients with available long-term pacing data, minimal pacemaker utilisation (pacing <5% at all checks) was observed in 13 (19%) patients. CONCLUSIONS: Pacemaker insertion in younger adults has significant long-term implications. Clinicians should carefully consider pacemaker insertion in this cohort given risk of device-related complications, potential for device under-utilisation and issues related to lead longevity. In addition, patients require close follow-up for development of structural abnormalities and arrhythmias.

Prediction of Pacemaker Requirement in Patients With Unexplained Syncope: The DROP Score.

BACKGROUND: Implantable loop recorders (ILR) are increasingly utilised in the evaluation of unexplained syncope. However, they are expensive and do not protect against future syncope. OBJECTIVES: To compare patients requiring permanent pacemaker (PPM) implantation during ILR follow-up with those without abnormalities detected on ILR in order to identify potential predictors of benefit from upfront pacing. METHODS: We analysed 100 consecutive patients receiving ILR: Group 1 (n=50) underwent PPM insertion due to bradyarrhythmias detected on ILR; Group 2 (n=50) had no arrhythmias detected on ILR over >3 years follow-up. Baseline clinical characteristics, syncope history, electrocardiographic and echocardiographic parameters were assessed to identify predictors of ultimate requirement for pacing. RESULTS: Group 1 (64% male, median age 70.8 years; IQR 65.5-78.8) were older than Group 2 (58% male, median 60.2 years; IQR 44.0-73.0 p=0.001) and were less likely to have related historical factors such as overheating, posture and exercise (98% vs 70% p<0.001). PR interval was also longer in Group 1 (192±51 vs 169±23 p=0.006) with greater prevalence of distal conduction system disease (30% vs 4.3% p=0.002). Significant univariate predictors for PPM insertion were distal conduction disease (p=0.007), first degree atrioventricular (AV) block (p=0.003), absence of precipitating factors (p=0.004), and age >65 years (p=0.001). Injury sustained, recurrent syncope, history of atrial fibrillation (AF) or heart failure, left atrial (LA) size and left ventricular ejection fraction (LVEF) were not predictive. These significant predictors were incorporated into the DROP score1 (0-4). Using time-to-event analysis, no patients with a score of 0 progressed to pacing, while higher scores (3-4) strongly predicted pacing requirement (log-rank p<0.001). CONCLUSION: The DROP score may be helpful in identifying patients likely to benefit from upfront permanent pacemaker (PPM) insertion following unexplained syncope. Larger prospective studies are required to validate this tool.

Driving with cardiac devices in Australia. Does a review of recent evidence prompt a change in guidelines?

Australian Driving Guidelines for patients with pacemakers and implanted cardioverter defibrillators are in line with many around the world, with some minor differences. Some aspects of these guidelines lack contemporary evidence in key decision-making areas and make broad recommendations regarding groups with heterogeneous populations. In addition, more recent studies suggest lower rates of adverse events in some patients with these devices than previously thought. Through a systematic literature review, along with discussion of current guidelines, we combine new evidence with well established risk assessment tools to ask the following questions: (i) Given the heterogeneity of patient risk within the defibrillator population, should guidelines allow for further individualisation of risk and subsequent licensing restrictions?; and (ii) Could some patients with primary prevention automated cardioverter defibrillators be able to hold a commercial driving licence?

Miniaturized implantable cardiac monitor with a long sensing vector (BIOMONITOR III): Insertion procedure assessment, sensing performance, and home monitoring transmission success.

BACKGROUND: Implantable Cardiac Monitors (ICMs) are used for long-term monitoring of arrhythmias. BIOMONITOR III is a novel ICM with a miniaturized profile, long sensing vector due to a flexible antenna, simplified implantation with a dedicated insertion tool for pocket formation and ICM placement in a single step, and daily automatic Home Monitoring (HM) function. METHODS: In 47 patients undergoing BIOMONITOR III insertion for any ICM indication, 16 investigators at 10 Australian sites assessed handling characteristics of the insertion tool, R-wave amplitudes, noise burden, P-wave visibility, and HM transmission success. Patients were followed for 1 month. RESULTS: All 47 attempted insertions were successful. Median time from skin incision to removal of the insertion tool after ICM insertion was 39 s (IQR 19-65) and to wound closure and cleaning was 4.7 min (IQR 3.5-7.8). All aspects of the insertion tool were rated as "good" or "excellent" in ≥97.9% and "fair" in ≤2.1% of patients, except for "force needed for tunnelling" (91.5% good/excellent, 8.5% fair). Based on HM data, R-waves in the first month were stable at 0.70 ± 0.37 mV. Median noise burden (disabling automatic rhythm evaluation) was 0.19% (IQR 0.00-0.93), equivalent to 2.7 min (IQR 0.0-13.4) per day. In HM-transmitted ECG strips with regular sinus rhythm, P-waves were visible in 89 ± 24% of heart cycles. Patient-individual automatic Home Monitoring transmission success was 98.0% ± 5.5%. CONCLUSIONS: The novel ICM performed well in all aspects studied, including fast insertion, reliable R-wave sensing, good P-wave visibility, and highly successful HM transmissions.

Increased Incidence of Noise in the Tendril Pacemaker Lead Detected via Remote Monitoring.

BACKGROUND: Prior studies suggest increased rates of noise on the Tendril (St Jude Medical/Abbott, St. Paul, MN, USA) pacemaker lead. We aim to assess the incidence of lead noise in the Tendril and 5076 (Medtronic PLC, Minneapolis, MN, USA) pacemaker leads in our cohort and in the process assess the utility of remote monitoring for identifying lead malfunction. METHODS: Deidentified, multi-centre, prospectively collected observational cohort data was obtained to assess the incidence of noise on the Tendril and 5076 pacemaker leads. RESULTS: 148 Tendril and 737 CapSureFix Novus 5076 (Medtronic, MN, USA) pacemaker leads were remotely monitored. Incidence of noise on the Tendril was 8% and 0.27% on the CapSureFix Novus. CONCLUSION: Rates of noise in the Tendril lead are higher than a market competitor. Remote monitoring is useful in detecting this concerning anomaly.

Rural and Remote Cardiology During the COVID-19 Pandemic: Cardiac Society of Australia and New Zealand (CSANZ) Consensus Statement.

THE CHALLENGES: Rural and remote Australians and New Zealanders have a higher rate of adverse outcomes due to acute myocardial infarction, driven by many factors. The prevalence of cardiovascular disease (CVD) is also higher in regional and remote populations, and people with known CVD have increased morbidity and mortality from coronavirus disease 2019 (COVID-19). In addition, COVID-19 is associated with serious cardiac manifestations, potentially placing additional demand on limited regional services at a time of diminished visiting metropolitan support with restricted travel. Inter-hospital transfer is currently challenging as receiving centres enact pandemic protocols, creating potential delays, and cardiovascular resources are diverted to increasing intensive care unit (ICU) and emergency department (ED) capacity. Regional and rural centres have limited staff resources, placing cardiac services at risk in the event of staff infection or quarantine during the pandemic. MAIN RECOMMENDATIONS: Health districts, cardiologists and government agencies need to minimise impacts on the already vulnerable cardiovascular health of regional and remote Australians and New Zealanders throughout the COVID-19 pandemic. Changes in management should include.

Position Statement on the Management of Cardiac Electrophysiology and Cardiac Implantable Electronic Devices in Australia During the COVID-19 Pandemic: A Living Document.

The COVID-19 pandemic poses a significant stress on health resources in Australia. The Heart Rhythm Council of the Cardiac Society of Australia and New Zealand aims to provide a framework for efficient resource utilisation balanced with competing risks when appropriately treating patients with cardiac arrhythmias. This document provides practical recommendations for the electrophysiology (EP) and cardiac implantable electronic devices (CIED) services in Australia. The document will be updated regularly as new evidence and knowledge is gained with time.

Mind the Gap: Mismatches Between Clinicians and Patients in Heart Failure Medication Management.

PURPOSE: Previous studies on the 'treatment gap' in patients with heart failure (HF) have focused either on prescribing or patients' adherence to prescribed treatment. This study sought to determine whether or not recent initiatives to close the gap have also minimised any mismatches between physicians' expectation of their patients' medications, medications in the patients' possession and their actual medication use. METHODS: A cross-sectional observational survey was conducted from December 2015 to June 2016 in The Alfred Hospital HF clinic in Melbourne, Australia. Patients were invited to participate if they had chronic HF (NYHA class II to IV), were aged ≥ 60 years, had no history of HF related hospitalisation within the past 6 months and were prescribed at least two HF medications. RESULTS: Of 123 eligible patients, 102 were recruited into the study. Beta-blockers, mineralocorticoid receptor antagonists, loop diuretics and statins were associated with the highest rates of mismatches of drugs and doses, ranging from 10 to 17%. Discrepancy of total daily doses was the most common type of mismatch. Overall, only 23.5% of the patients were taking the right drugs at the right doses as expected by their cardiologists/HF specialists. CONCLUSIONS: Despite improved prescribers' adherence to guideline-directed medical therapy, there remain considerable mismatches between prescribers' expectation of patients' HF medications, medications in patients' possession and their actual medication use. Initiatives to improve this situation are urgently needed.

Absence of late gadolinium enhancement on cardiac magnetic resonance imaging in ventricular fibrillation and nonischemic cardiomyopathy.

INTRODUCTION: Cardiac magnetic resonance (CMR)-identified late gadolinium enhancement (LGE), representing regional fibrosis, is often used to predict ventricular arrhythmia risk in nonischemic cardiomyopathy (NICM). However, LGE is more closely correlated with sustained monomorphic ventricular tachycardia (SMVT) than ventricular fibrillation (VF). We characterized CMR findings of ventricular LGE in VF survivors. METHODS: We examined consecutively resuscitated VF survivors undergoing contrast-enhanced 1.5T CMR between 9/2007 and 7/2016. We excluded coronary artery disease, hypertrophic cardiomyopathy, amyloid, sarcoid, arrhythmogenic right ventricular cardiomyopathy, and channelopathy. Preexisting implantable cardioverter-defibrillator (ICD) was a CMR contraindication. VF patients were divided into three groups: (1) NICM, (2) left ventricular (LV) dilatation with normal LV ejection fraction (LVEF), and (3) normal LV size and LVEF. Two groups of NICM patients with and without SMVT were examined for comparison. RESULTS: We analyzed 87 VF patients, and found that LGE was seen in 8/22 (36%) with NICM (LVEF 38 ± 11%, LV end-diastolic volume index [LVEDVI] 134 ± 68 mL/BSA), 11/40 (28%) with LV dilatation and normal LVEF (LVEDVI 103 ± 17 mL/BSA), 4/25 (16%) with normal LV size and LVEF. Incidence of LGE in NICM patients without prior ventricular tachycardia/VF (LVEF 36 ± 12%, LVEDVI 141 ± 46 mL/body surface area [BSA]) was 117/277 and was not lower than those with VF and NICM (42% vs 36%; P = 0.59). By contrast, 22/37 NICM patients with SMVT (LVEF 42 ± 11%, LVEDVI 123 ± 48 mL/BSA) were LGE-positive (59% NICM-SMVT vs 36% NICM-VF; P = 0.04). CONCLUSION: Most VF survivors with a diagnosis of NICM did not have LGE on CMR and would not have met primary prevention ICD criteria based on LVEF. Absence of LGE may not portend a benign prognosis in NICM. Novel strategies for determining SCD risk in this cohort are required.

Implantable cardioverter defibrillator knowledge and end-of-life device deactivation: A cross-sectional survey.

BACKGROUND: End-of-life implantable cardioverter defibrillator deactivation discussions should commence before device implantation and be ongoing, yet many implantable cardioverter defibrillators remain active in patients' last days. AIM: To examine associations among implantable cardioverter defibrillator knowledge, patient characteristics and attitudes to implantable cardioverter defibrillator deactivation. DESIGN: Cross-sectional survey using the Experiences, Attitudes and Knowledge of End-of-Life Issues in Implantable Cardioverter Defibrillator Patients Questionnaire. Participants were classified as insufficient or sufficient implantable cardioverter defibrillator knowledge and the two groups were compared. SETTING/PARTICIPANTS: Implantable cardioverter defibrillator recipients ( n = 270, mean age 61 ± 14 years; 73% male) were recruited from cardiology and implantable cardioverter defibrillator clinics attached to two tertiary hospitals in Melbourne, Australia, and two in Kentucky, the United States. RESULTS: Participants with insufficient implantable cardioverter defibrillator knowledge ( n = 77, 29%) were significantly older (mean age 66 vs 60 years, p = 0.001), less likely to be Caucasian (77% vs 87%, p = 0.047), less likely to have received implantable cardioverter defibrillator shocks (26% vs 40%, p = 0.031), and more likely to have indications of mild cognitive impairment (Montreal Cognitive Assessment score <24: 44% vs 16%, p < 0.001). Insufficient implantable cardioverter defibrillator knowledge was associated with attitudes suggesting unwillingness to discuss implantable cardioverter defibrillator deactivation, even during the last days towards end of life ( p < 0.05). CONCLUSION: Implantable cardioverter defibrillator recipients, especially those who are older or have mild cognitive impairment, often have limited knowledge about implantable cardioverter defibrillator deactivation. This study identified several potential teachable moments throughout the patients' treatment trajectory. An interdisciplinary approach is required to ensure that discussions about implantable cardioverter defibrillator deactivation issues are initiated at appropriate time points, with family members ideally also included.

Trends in outpatient anti-arrhythmic prescriptions for atrial fibrillation and left atrial ablation in Australia: 1997-2016.

BACKGROUND: An important aspect of atrial fibrillation (AF) management is the decision whether to adopt a rate or rhythm control strategy. Options for the latter include oral anti-arrhythmic drugs (AAD) or catheter ablation. AIM: To describe the trends in rhythm control for AF in Australia between 1997 and 2016. METHODS: We conducted a retrospective study using prospectively collected data between 1997 and 2016 from the Pharmaceutical Benefit Scheme and Medicare Benefit Schedule websites, which, respectively, contain information pertaining to public AAD prescriptions and rebatable AF ablation procedures performed in Australia. RESULTS: Sotalol and amiodarone remain the most commonly prescribed AAD in Australia, although their use is decreasing. Rates of catheter ablation for AF continue to rise annually with a 48-fold increase from 71 to 3480 since 1997. CONCLUSION: A rhythm control strategy is frequently utilised for AF management in Australia. Consistent with international guidelines which advocate safety over efficacy when choosing a rhythm control strategy, the prescriptions of amiodarone have been consistently decreasing since 2002, whereas sotalol and flecainide prescriptions have largely increased, with a peak in 2015. Catheter ablation per capita has burgeoned 36-fold.

Cardiac implantable electronic device hematomas: Risk factors and effect of prophylactic pressure bandaging.

BACKGROUND: Cardiac implantable electronic device (CIED) hematomas are associated with many adverse outcomes. We examined the incidence and risk factors associated with hematoma formation post-CIED implantation, and explored the preventative effect of prophylactic pressure bandaging (PPB) in a large tertiary center. METHODS: 1,091 devices were implanted during October 2011-December 2014. Clinically significant hematomas (CSH) were those that necessitated prolonged admission, including those due to reoperation, and clinically suspicious hematomas were swellings noted by medical/nursing staff. We screened for variables affecting hematoma incidence prior to conducting multivariate logistic regression analyses, one for all hematomas and one for CSH. RESULTS: 61 hematomas were identified (5.6% of patients), with 12 of those clinically significant (1.1% of patients). Factors significantly increasing the odds of developing any hematoma were stage 2 (odds ratio [OR] = 2.93, 95% confidence interval [CI] [1.08-7.94], P = 0.034) and 3 chronic kidney disease (CKD) (OR = 3.39 [1.20-9.56], P = 0.021), unfractionated heparin/therapeutic enoxaparin (OR = 3.15 [1.22-8.14], P = 0.018), and dual antiplatelets-aspirin + clopidogrel (OR = 2.95 [1.14-7.65], P = 0.026) + other combinations. Body Mass index (BMI) 25.0-29.9 (OR 0.52 [0.28-0.98], P = 0.044) and >30 were associated with decreased hematoma risk (OR 0.43 [0.20-0.91], P = 0.028). Factors significant for CSH formation were unfractionated heparin/therapeutic enoxaparin (OR = 9.55 [1.83-49.84], P = 0.007) and aspirin + clopidogrel (OR = 7.19 [1.01-50.91], P = 0.048). PPB nonsignificantly increased the odds of total hematoma development (OR = 1.53 [0.87-2.69], P = 0.135), and reduced CSH (OR = 0.67 [0.18-2.47], P = 0.547). CONCLUSIONS: Heparin and dual antiplatelet use remain strong predictors of overall hematoma formation. CKD is a comparatively moderate predictor. BMI > 25 may decrease the risk of hematoma formation. PPB had nonsignificant effects on hematoma development.

Diffuse Ventricular Fibrosis on Cardiac Magnetic Resonance Imaging Associates With Ventricular Tachycardia in Patients With Hypertrophic Cardiomyopathy.

INTRODUCTION: Non-sustained ventricular tachycardia (NSVT) is a risk factor for sudden cardiac death (SCD) in patients with hypertrophic cardiomyopathy (HCM). We aimed to assess whether diffuse ventricular fibrosis on cardiac magnetic resonance (CMR) imaging could be a surrogate marker for ventricular arrhythmias in patients with HCM. METHODS: A total of 100 patients with HCM (mean age 51 ± 13 years, septal wall thickness 20 ± 5 mm) underwent CMR with a 1.5 T scanner to determine the presence of ventricular late gadolinium enhancement (LGE) for focal fibrosis, and post-contrast T1 mapping for diffuse ventricular fibrosis. The presence of NSVT was determined by Holter monitoring and a subset of high risk patients received an implantable cardioverter-defibrillator (ICD). RESULTS: NSVT was detected in 23 of 100 patients with HCM. Focal ventricular fibrosis (by LGE) was observed in 87%, with no significant difference between patients with (96%) or without NSVT (86%, P = 0.19). However, LGE mass was greater in patients with (16.5 ± 19.1 g) versus without NSVT (7.6 ± 10.2 g, P < 0.01). NSVT was associated with a significant reduction in ventricular T1 relaxation time (422 ± 54 milliseconds) versus patients without NSVT (512 ± 115 milliseconds; P < 0.001). There was significant reduction in ventricular T1 relaxation time in patients with (430 ± 48 milliseconds) versus without aborted SCD (495 ± 113 milliseconds; P = 0.01) over a mean follow-up of 40 ± 10 months. On multivariate analysis post-contrast ventricular T1 relaxation time and septal wall thickness were the only predictors of NSVT. CONCLUSION: Post-contrast T1 relaxation time on CMR is associated with ventricular arrhythmias in patients with HCM. Diffuse ventricular fibrosis may be an important marker of arrhythmic risk in patients with HCM.

The Impact of Known Heart Disease on Long-Term Outcomes of Catheter Ablation in Patients with Atrial Fibrillation and Left Ventricular Systolic Dysfunction: A Multicenter International Study.

BACKGROUND: Catheter ablation for AF is an effective treatment for patients with AF and systolic LV dysfunction; however, the clinical outcome is variable. We evaluated the impact of cardiomyopathy etiology on long-term outcomes post-catheter ablation. METHODS: Patients undergoing AF ablation across 3 centers (2 Australian, 1 UK) from 2002 to 2014, with LVEF<45% were evaluated. Patients were stratified into those with known heart disease as a cause of cardiomyopathy (KHD), and those with idiopathic dilated cardiomyopathy (IDCM). RESULTS: One hundred and one patients (IDCM = 77, KHD = 24) with AF and LVEF <45% underwent AF ablation. The KHD group (ischemic HD in 67%) were older (61 ± 7 vs. 55 ± 11 years, P = 0.005), with a higher CHADS2 score (2.0 ± 0.8 vs. 1.6 ± 0.7, P = 0.016), but otherwise well matched. After mean follow-up of 36 ± 23 months, AF control was greater in the IDCM group (82% vs. 50% in KHD, P < 0.001). On multivariate analysis IDCM was associated with long-term AF control (P = 0.033). The IDCM group had less functional impairment at follow-up (NYHA class 1.5 ± 0.7 vs. 2.0 ± 0.8, P = 0.005) and improved LVEF (50 ± 11% vs. 38 ± 10%, P < 0.001). Super responders (EF improvement >15%) were overwhelmingly in the IDCM group (94% vs. 6%, P < 0.001) with greater AF control (89% vs. 61%, P < 0.001). All-cause mortality was significantly higher in the KHD group (17% vs. 1.3%, P = 0.002). CONCLUSION: IDCM was associated with greater AF control, and improvement in symptoms and LVEF compared to patients with KHD post-AF ablation. AF is an important reversible cause of HF in patients with an unexplained CM and catheter ablation an effective treatment option.

Cardiac Implantable Electronic Devices and End-of-Life Care: An Australian Perspective.

Cardiac implantable electronic devices (pacemakers and defibrillators) are increasingly common in modern cardiology practice, and health professionals from a variety of specialties will encounter patients with such devices on a frequent basis. This article will focus on the subset of patients who may request, or be appropriate for, device deactivation and discuss the issues surrounding end-of-life decisions, along with the ethical and legal implications of device deactivation.

Reduction in peripheral vascular resistance predicts improvement in insulin clearance following weight loss.

BACKGROUND: The hyperinsulinemia of obesity is a function of both increased pancreatic insulin secretion and decreased insulin clearance, and contributes to cardiovascular risk. Whilst weight loss is known to enhance insulin clearance, there is a paucity of data concerning the underlying mechanisms. This study was conducted to examine the inter-relationships between changes in sympathetic nervous system (SNS) activity, vascular function and insulin clearance during a weight loss program. METHODS: Seventeen non-smoking, un-medicated individuals aged 55 ± 1 years (mean ± SEM), body mass index (BMI) 33.9 ± 1.7 kg/m(2), underwent a 4-month hypocaloric diet (HCD), using a modified Dietary Approaches to Stop Hypertension diet, whilst seventeen age- and BMI-matched subjects acted as controls. Insulin sensitivity and insulin clearance were assessed via euglycemic hyperinsulinemic clamp (exogenous insulin clearance); hepatic insulin extraction was calculated as fasting C-peptide to insulin ratio (endogenous insulin clearance); SNS activity was quantified by microneurographic nerve recordings of muscle sympathetic nerve activity (MSNA) and whole-body norepinephrine kinetics; and vascular function by calf venous occlusion plethysmography and finger arterial tonometry. RESULTS: Weight loss averaged -8.3 ± 0.6% of body weight in the HCD group and was accompanied by increased clamp-derived glucose utilization (by 20 ± 9%, P = 0.04) and exogenous insulin clearance (by 12 ± 5%, P = 0.02). Hepatic insulin extraction increased from 6.3 ± 0.8 to 7.1 ± 0.9 (P = 0.09). Arterial norepinephrine concentration decreased by -12 ± 5%, whole-body norepinephrine spillover rate by -14 ± 8%, and MSNA by -9 ± 5 bursts per 100 heartbeats in the HCD group (P all >0.05 versus control group). Step-wise regression analysis revealed a bidirectional relationship between enhanced exogenous insulin clearance post weight loss and reduction in calf vascular resistance (r = -0.63, P = 0.01) which explained 40% of the variance. Increase in hepatic insulin extraction was predicted by enhanced finger reactive hyperaemic response (P = 0.006) and improvement in oral glucose tolerance (P = 0.002) which together explained 64% of the variance. CONCLUSIONS: Insulin clearance is independently and reciprocally associated with changes in vascular function during weight loss intervention. Trial registration ClinicalTrials.gov: NCT01771042 and NCT00408850.