Cardiac rehabilitation for participants with implantable cardiac devices: A systematic review and meta-analysis.

Aim: The aim is to discuss efficacy and safety of exercise-based cardiac rehabilitation (CR) programmes in participants with implantable cardiac devices compared with usual care. Methods: MEDLINE, EMBASE and Cochrane databases were searched from inspection till July 15, 2022. Randomized controlled trials were included if they enrolled adult participants with implantable cardiac devices and tested exercise-based CR interventions in comparison with any control. Risk of bias was assessed, and endpoints data were pooled using random-effects model. Results: Sixteen randomized trials enrolling 2053 participants were included. Study interventions differed between studies in terms of programme components, setting, exercise intensity, and follow-up. All studies included physical exercise component. In both implantable cardioverter defibrillators (ICD) and cardiac resynchronization therapy (CRT) groups, exercise training in CR programmes improved peak oxygen uptake (VO2) [(mean difference (MD) 2.08 ml/kg/min; 95 % CI: 1.44-2.728, p < 0.0001; I2 = 99 %) and (MD 2.24 ml/kg/min; 95 % CI: 1.43-3.04, p < 0.0001; I2 = 96 %), respectively] and 6-min walk test in ICD group (MD 41.51 m; 95 % CI: 15.19-67.82 m, p = 0.002; I2 = 95 %) compared with usual care. In CRT group, there was no statistically significant improvement in left ventricular ejection fraction change between comparison groups. The results were consistent in subgroup analysis according to high or low-to-moderate exercise intensity for change in peak VO2 and ejection fraction in CRT group. There was no difference in number of ICD shocks between the comparators. Conclusion: Exercise-based CR programmes appear to be safe when enrolling participants with implantable cardiac devices and leading to favourable functional outcomes.

Ablation versus anti-arrhythmic therapy for reducing all hospital episodes from recurrent atrial fibrillation: a prospective, randomized, multi-centre, open label trial.

AIMS: There is rising healthcare utilization related to the increasing incidence and prevalence of atrial fibrillation (AF) worldwide. Simplifying therapy and reducing hospital episodes would be a valuable development. The efficacy of a streamlined AF ablation approach was compared to drug therapy and a conventional catheter ablation technique for symptom control in paroxysmal AF. METHODS AND RESULTS: We recruited 321 patients with symptomatic paroxysmal AF to a prospective randomized, multi-centre, open label trial at 13 UK hospitals. Patients were randomized 1:1:1 to cryo-balloon ablation without electrical mapping with patients discharged same day [Ablation Versus Anti-arrhythmic Therapy for Reducing All Hospital Episodes from Recurrent (AVATAR) protocol]; optimization of drug therapy; or cryo-balloon ablation with confirmation of pulmonary vein isolation and overnight hospitalization. The primary endpoint was time to any hospital episode related to treatment for atrial arrhythmia. Secondary endpoints included complications of treatment and quality-of-life measures. The hazard ratio (HR) for a primary endpoint event occurring when comparing AVATAR protocol arm to drug therapy was 0.156 (95% CI, 0.097-0.250; P < 0.0001 by Cox regression). Twenty-three patients (21%) recorded an endpoint event in the AVATAR arm compared to 76 patients (74%) within the drug therapy arm. Comparing AVATAR and conventional ablation arms resulted in a non-significant HR of 1.173 (95% CI, 0.639-2.154; P = 0.61 by Cox regression) with 23 patients (21%) and 19 patients (18%), respectively, recording primary endpoint events (P = 0.61 by log-rank test). CONCLUSION: The AVATAR protocol was superior to drug therapy for avoiding hospital episodes related to AF treatment, but conventional cryoablation was not superior to the AVATAR protocol. This could have wide-ranging implications on how demand for AF symptom control is met. TRIAL REGISTRATION: Clinical Trials Registration: NCT02459574.

Chronic reduction of store operated Ca2+ entry is viable therapeutically but is associated with cardiovascular complications.

Loss of function mutations in store-operated Ca2+ entry (SOCE) are associated with severe paediatric disorders in humans, including combined immunodeficiency, anaemia, thrombocytopenia, anhidrosis and muscle hypotonia. Given its central role in immune cell activation, SOCE has been a therapeutic target for autoimmune and inflammatory diseases. Treatment for such chronic diseases would require prolonged SOCE inhibition. It is, however, unclear whether chronic SOCE inhibition is viable therapeutically. Here we address this issue using a novel genetic mouse model (SOCE hypomorph) with deficient SOCE, nuclear factor of activated T cells activation, and T cell cytokine production. SOCE hypomorph mice develop and reproduce normally and do not display muscle weakness or overt anhidrosis. They do, however, develop cardiovascular complications, including hypertension and tachycardia, which we show are due to increased sympathetic autonomic nervous system activity and not cardiac or vascular smooth muscle autonomous defects. These results assert that chronic SOCE inhibition is viable therapeutically if the cardiovascular complications can be managed effectively clinically. They further establish the SOCE hypomorph line as a genetic model to define the therapeutic window of SOCE inhibition and dissect toxicities associated with chronic SOCE inhibition in a tissue-specific fashion. KEY POINTS: A floxed stromal interaction molecule 1 (STIM1) hypomorph mouse model was generated with significant reduction in Ca2+ influx through store-operated Ca2+ entry (SOCE), resulting in defective nuclear translocation of nuclear factor of activated T cells, cytokine production and inflammatory response. The hypomorph mice are viable and fertile, with no overt defects. Decreased SOCE in the hypomorph mice is due to poor translocation of the mutant STIM1 to endoplasmic reticulum-plasma membrane contact sites resulting in fewer STIM1 puncta. Hypomorph mice have similar susceptibility to controls to develop diabetes but exhibit tachycardia and hypertension. The hypertension is not due to increased vascular smooth muscle contractility or vascular remodelling. The tachycardia is not due to heart-specific defects but rather seems to be due to increased circulating catecholamines in the hypomorph. Therefore, long term SOCE inhibition is viable if the cardiovascular defects can be managed clinically.

Protocol update for a randomised controlled feasibility trial of exercise rehabilitation for people with postural tachycardia syndrome: the PULSE study.

BACKGROUND: The PULSE (PostUraL tachycardia Syndrome Exercise) study is a randomised controlled trial assessing the feasibility of conducting a multicentre RCT testing supervised exercise rehabilitation with behavioural and motivational support, compared to best-practice usual care, for people with Postural Tachycardia Syndrome (PoTS). The original trial protocol was published in BMC Pilot & Feasibility Studies (accessible at https://doi.org/10.1186/s40814-020-00702-1 ). The PULSE intervention consists of (1) individual assessment; (2) 12-week, twice-weekly, supervised exercise training; (3) behavioural and motivational support; and (4) guided lifestyle physical activity. The control intervention is best-practice usual care with a single 30-min, one-to-one practitioner appointment, and general advice on safe and effective physical activity. Sixty-two people (aged 18-60 years) with a confirmed diagnosis of PoTS will be invited to enrol on a feasibility RCT with an embedded qualitative study. The primary outcome will be feasibility; process-related measures will include eligibility, recruitment, randomisation and withdrawal rates, along with indicators of exercise programme adherence and acceptability. Secondary physiological, clinical and health-related outcomes will be assessed. In response to the COVID-19 pandemic, here we describe amendments to the trial protocol. METHODS: Restrictions imposed by the COVID-19 pandemic meant it was necessary to change the delivery of the PULSE and control interventions. These changes reflected the need to limit the risk of COVID-19 transmission in a clinical population, some of whom were at increased risk of contracting the virus and suffering serious illness. The major change was that the originally intended centre-based PULSE and control interventions would now be delivered remotely on-line. Subsequently, there were minor changes to the participant eligibility criteria. These decisions followed an on-line co-creation session with people affected by PoTS, and relevant public and professional stakeholders. CONCLUSIONS: We present an update of the original trial protocol in response to the COVID-19 pandemic. No participants were recruited to the original protocol; thus, results will reflect the on-line delivery of the intervention. PULSE will be the first randomised trial to assess the feasibility of conducting a definitive multi-centre RCT testing supervised on-line exercise rehabilitation with behavioural and motivational support, compared to best-practice usual care, for people with PoTS. TRIAL REGISTRATION: ISRCTN45323485 registered on 7 April 2020.

Safety and outcome of nurse-led syncope clinics and implantable loop recorder implants.

BACKGROUND: Implantable loop recorders (ILRs) are effective in achieving symptom-rhythm correlation. Data on the diagnostic yield of ILRs, on nurse-led syncope clinics, and on nurse-led ILR implants are limited. OBJECTIVE: We evaluated the safety and efficacy of our nurse-led syncope clinic and nurse-led ILR implants. METHODS: A retrospective study of all consecutive patients undergoing nurse-led ILR implantations was performed between April 2016 and April 2018. Patients were referred from both nurse-led and physician-led clinics. Data were collected on baseline demographic characteristics, referral source, symptom-rhythm correlation, ILR findings, and subsequent changes to management. All ILRs were enrolled into remote monitoring with automatic arrhythmia detection, and all immediate (≤24 hours) ILR implant complications were recorded. Comparisons were made between nurse-led and physician-led clinics and subsequent outcomes. RESULTS: A total of 432 patients with an ILR were identified: 164 (38%) from nurse-led and 268 (62%) from physician-led clinics; 200 (46%) were women (mean age 66.5 ± 18.2 years; mean follow-up duration 28.9 ± 9.5 months). Primary ILR indications were syncope (n = 251 [58%]), presyncope (n = 33 [7%]), palpitation (n = 39 [9%]), cryptogenic stroke (n = 78 [18%]), and other reasons (n = 31 [7%]). No immediate ILR implant complications occurred. Overall, 156 patients (36%) had a change in management as a direct result of ILR findings, with no overall differences between nurse-led and physician-led clinics (35% vs 36%; P = .7). More patients had newly diagnosed atrial fibrillation in physician-led clinics (15% vs 7%; P = .01), and more patients had pacemaker implants for bradycardia in nurse-led clinics (23% vs 13%; P < .01). CONCLUSION: Nurse-led ILR implantation was safe and effective. Nurse-led syncope clinics achieved good symptom-rhythm correlation with resultant significant changes to management in comparison to physician-led clinics. Larger prospective studies are needed to evaluate their longer-term impact.

Impact of a high-density grid catheter on long-term outcomes for structural heart disease ventricular tachycardia ablation.

BACKGROUND: Substrate mapping has highlighted the importance of targeting diastolic conduction channels and late potentials during ventricular tachycardia (VT) ablation. State-of-the-art multipolar mapping catheters have enhanced mapping capabilities. The purpose of this study was to investigate whether long-term outcomes were improved with the use of a HD Grid mapping catheter combining complementary mapping strategies in patients with structural heart disease VT. METHODS: Consecutive patients underwent VT ablation assigned to either HD Grid, Pentaray, Duodeca, or point-by-point (PbyP) RF mapping catheters. Clinical endpoints included recurrent anti-tachycardia pacing (ATP), appropriate shock, asymptomatic non-sustained VT, or all-cause death. RESULTS: Seventy-three procedures were performed (33 HD Grid, 22 Pentaray, 12 Duodeca, and 6 PbyP) with no significant difference in baseline characteristics. Substrate mapping was performed in 97% of cases. Activation maps were generated in 82% of HD Grid cases (Pentaray 64%; Duodeca 92%; PbyP 33% (p = 0.025)) with similar trends in entrainment and pace mapping. Elimination of all VTs occurred in 79% of HD Grid cases (Pentaray 55%; Duodeca 83%; PbyP 33% (p = 0.04)). With a mean follow-up of 372 ± 234 days, freedom from recurrent ATP and shock was 97% and 100% respectively in the HD Grid group (Pentaray 64%, 82%; Duodeca 58%, 83%; PbyP 33%, 33% (log rank p = 0.0042, p = 0.0002)). CONCLUSIONS: This study highlights a step-wise improvement in survival free from ICD therapies as the density of mapping capability increases. By using a high-density mapping catheter and combining complementary mapping strategies in a strict procedural workflow, long-term clinical outcomes are improved.

Safety and cost-effectiveness of same-day complex left atrial ablation.

BACKGROUND: Catheter ablation for complex left-atrial arrhythmia is increasing worldwide with many centres admitting patients overnight. Same-day procedures using conscious sedation carry significant benefits to patients/healthcare providers but data are limited. We evaluated the safety and cost-effectiveness of same-day complex left-atrial arrhythmia ablation. METHOD: Multi-centre retrospective cohort study of all consecutive complex elective left-atrial ablation procedures performed between January 2011 and December 2019. Data were collected on planned same-day discharge versus overnight stay, baseline parameters, procedure details/success, ablation technology, post-operative complications, unplanned overnight admissions/outcomes at 4-months and mortality up to April 2020. A cost analysis of potential savings was also performed. RESULTS: A total of 967 consecutive patients underwent complex left-ablation using radiofrequency (point-by-point ablation aided by 3D-mapping or PVAC catheter ablation with fluoroscopic screening) or cryoballoon-ablation (mean age: 60.9 ± 11.6 years, range 23-83 yrs., 572 [59%] females). The majority of patients had isolation of pulmonary veins alone (n = 846, 87%) and most using conscious-sedation alone (n = 921, 95%). Of the total cohort, 414 (43%) had planned same-day procedure with 35 (8%) admitted overnight due to major (n = 5) or minor (n = 30) complications. Overall acute procedural success-rate was 96% (n = 932). Complications in planned overnight-stay/same-day cohorts were low. At 4-month follow-up there were 62 (6.4%) readmissions (femoral haematomas, palpitation, other reasons); there were 3 deaths at mean follow-up of 42.0 ± 27.6 months, none related to the procedure. Overnight stay costs £350; the same-day ablation policy over this period would have saved £310,450. CONCLUSIONS: Same-day complex left-atrial catheter ablation using conscious sedation is safe and cost-effective with significant benefits for patients and healthcare providers. This is especially important in the current financial climate and Covid-19 pandemic.

Brugada Syndrome: Clinical Features, Risk Stratification, and Management.

In 1992, the Brugada brothers published a patient series of aborted sudden death, who were successfully resuscitated from ventricular fibrillation (VF). These patients had a characteristic coved ST-segment elevation in the right precordial leads on their 12-lead electrocardiogram with no apparent structural heart abnormality. This disease was referred to as "right bundle branch block, persistent ST-segment elevation, and sudden death syndrome." The term Brugada syndrome (BrS) was first coined for this new arrhythmogenic entity in 1996. BrS is more prevalent in Southeast Asian ethnic groups and was considered a familial disease due to the presence of syncope and/or sudden deaths in several members of the same family, however, the genetic alteration was only noted in 1998. The genetic characterization of BrS has proven to be challenging. The most common and well-established BrS genotype involves loss-of-function mutations in the SCN5A gene, but only represents between 15% and 30% of the diagnosed patients. Patients with BrS can present with a range of symptoms which can include syncope, seizures, and nocturnal agonal breathing due to polymorphic ventricular tachycardia or VF. If these arrhythmias are sustained, sudden cardiac death may result. Despite the significant progress on the understanding of BrS over the last two decades, there remain a number of uncertainties and challenges; we present an update review on the subject.

Epilepsy and Brugada Syndrome: Association or Uncommon Presentation?

Brugada syndrome (BrS) is a rare genetic disease, of which its clinical manifestations include, but not limited to, syncope or sudden cardiac death. A 30-year-old Bangladeshi male patient with a past medical history of epilepsy was admitted following successful resuscitation from an out of hospital cardiac arrest secondary to ventricular fibrillation. Electrocardiogram (ECG) upon admission was suggestive of BrS type I. His old medical record showed similar ECG 2 months earlier when he had presented with syncope and was diagnosed with seizure. The correlation between BrS and epilepsy has been reported in the literature, discussing whether seizure is an uncommon presentation of BrS or whether epilepsy and BrS share similar genetic mutations that have the potential to cause both arrhythmia and seizures in some patients. Patients who present with seizure and ECG suggestive of Brugada pattern should be evaluated to rule out associated or underlying cardiac arrhythmia.

The Impact of a Nurse-Led Syncope Clinic: Experience from a single UK tertiary center.

BACKGROUND: Syncope is a leading cause of hospital admission and is associated with significant morbidity and mortality. Our Syncope Clinic commenced in 2014 and we sought to evaluate its impact on outcomes (1-yr mortality and syncope re-hospitalization) in patients discharged following syncope admission. METHODS: A single-center study of all consecutive patients discharged with syncope (ICD-10 R55) between April 2012 and 2017. Patient demographics, comorbidities, hospital stay, syncope re-hospitalization, and mortality at one-year were collected. Those subsequently referred and seen in Syncope Clinic were compared with those who were not and predictors of poor outcome were evaluated. RESULTS: In total 2950 patients were discharged from hospital with syncope (median age: 73years, 51% male) with 1220 (41%) discharged same-day; after commencement of Syncope Clinic 231were subsequently reviewed here. Overall mortality was 11%, which was lower in the Syncope Clinic group (3% vs 12%, P < .001). Temporal analysis revealed reduced re-hospitalization following commencement of Syncope Clinic (2% vs 6%, P = .027). Independent predictors of mortality were increasing age (HR 1.03, 95% CI 1.03-1.04), AF (HR 1.6, 95% CI 1.2-2.1), HF (HR 2.2, 95% CI 1.6-3.0), COPD (HR 1.9, 95% CI 1.4-2.7), and CHADS2 score ≥ 1 (HR 1.45, 95% CI 1,12-1.87). Syncope Clinic attendance was associated with reduced mortality (HR 0.3, 95% CI 0.1-0.6). CONCLUSIONS: Syncope patients discharged from hospital had reduced 1yr mortality if seen in subsequent Syncope Clinic. Independent predictors of mortality were COPD, HF, AF, and CHADS2 ≥1. Prospective randomized trials of Syncope Clinics are warranted.

Protocol for a randomised controlled feasibility trial of exercise rehabilitation for people with postural tachycardia syndrome: the PULSE study.

BACKGROUND: Postural orthostatic tachycardia syndrome (POTS) is an autonomic nervous system disorder causing an abnormal cardiovascular response to upright posture. It affects around 0.2% of the population, most commonly women aged 13 to 50 years. POTS can be debilitating; prolonged episodes of pre-syncope and fatigue can severely affect activities of daily living and health-related quality of life (HRQoL). Medical treatment is limited and not supported by randomised controlled trial (RCT) evidence. Lifestyle interventions are first-line treatment, including increased fluid and salt intake, compression tights and isometric counter-pressure manoeuvres to prevent fainting. Observational studies and small RCTs suggest exercise training may improve symptoms and HRQoL in POTS, but evidence quality is low. METHODS: Sixty-two people (aged 18-40 years) with a confirmed diagnosis of POTS will be invited to enrol on a feasibility RCT with embedded qualitative study. The primary outcome will be feasibility; process-related measures will include the number of people eligible, recruited, randomised and withdrawn, along with indicators of exercise programme adherence and acceptability. Secondary physiological, clinical and health-related outcomes including sub-maximal recumbent bike exercise test, active stand test and HRQoL will be measured at 4 and 7 months post-randomisation by researchers blinded to treatment allocation. The PostUraL tachycardia Syndrome Exercise (PULSE) intervention consists of (1) individual assessment; (2) 12-week, once to twice-weekly, supervised out-patient exercise training; (3) behavioural and motivational support; and (4) guided lifestyle physical activity. The control intervention will be best-practice usual care with a single 30-min, one-to-one practitioner appointment, and general advice on safe and effective physical activity. For the embedded qualitative study, participants (n = 10 intervention, n = 10 control) will be interviewed at baseline and 4 months post-randomisation to assess acceptability and the feasibility of progressing to a definitive trial. DISCUSSION: There is very little high-quality research investigating exercise rehabilitation for people with POTS. The PULSE study will be the first randomised trial to assess the feasibility of conducting a definitive multicentre RCT testing supervised exercise rehabilitation with behavioural and motivational support, compared to best-practice usual care, for people with POTS. TRIAL REGISTRATION: ISRCTN45323485 registered on 7 April 2020.

Tissue Doppler-Derived Left Ventricular Systolic Velocity Is Associated with Lethal Arrhythmias in Cardiac Device Recipients Irrespective of Left Ventricular Ejection Fraction.

BACKGROUND: Life-threatening arrhythmias (LTAs) can trigger sudden cardiac death or provoke implantable cardioverter-defibrillator (ICD) discharges that escalate morbidity and mortality. Longitudinal myofibrils predominate in the subendocardium, which is uniquely sensitive to arrhythmogenic triggers. In this study, we test the hypothesis that mitral annular systolic velocity (S'), a simple routinely obtained tissue Doppler index of LV long-axis systolic function, might predict lethal arrhythmias irrespective of left ventricular ejection fraction (LVEF). METHODS: This is a retrospective analysis of data from 302 patients (mean age, 68 years; LVEF, 32%; 77% male; 52% ischemic; 35% primary prevention; and 53% cardiac resynchronization therapy defibrillator [CRT-D]) who were followed up (median, 15 months) at two centers after receipt of an ICD or CRT-D for diverse indications. S', averaged from tissue Doppler-derived medial and lateral mitral annular velocities, was correlated with the primary outcome of time to sustained ventricular tachycardia (VT) or fibrillation (VF) needing device therapy. RESULTS: The median S' was 5.1 (interquartile range, 4.0-6.2) cm/sec and lower in CRT-D than ICD subjects (4.5 [3.8-5.6] cm/sec vs 5.5 [4.8-6.8] cm/sec, P < .001). Fifty-six (19%) subjects had LTA. Each 1 cm/sec higher S' correlated to a 30% decreased risk of LTA (hazard ratio = 0.70; 95% CI, 0.57-0.87; P = .001) independently of age, sex, ß-blocker use, center, ICD use, and LVEF. Adding S' to the baseline Cox model improved net reclassification (P = .02). An S' > 5.6 cm/sec was the best cutoff and linked to a 58% lower LTA risk than an S' ≤ 5.6 cm/sec (95% CI, 0.23-0.85; P = .02). CONCLUSIONS: A higher S' is associated with a reduced probability of LTA in cardiac device recipients irrespective of LVEF and may have the potential to be used clinically to titrate medical, device, and ablative therapies to mitigate future arrhythmic risk.

Enhanced ventricular tachycardia substrate resolution with a novel omnipolar high-density mapping catheter: the omnimapping study.

BACKGROUND: Defining diastolic slow-conduction channels within the borderzone (BZ) of scar-dependent re-entrant ventricular tachycardia (VT) is key for effective mapping and ablation strategies. Understanding wavefront propagation is driving advances in high-density (HD) mapping. The newly developed Advisor™ HD Grid Mapping Catheter (HD GRID) has equidistant spacing of 16, 1 mm electrodes in a 4 × 4 3 mm interspaced arrangement allowing bipolar recordings along and uniquely across the splines (orthogonal vector) to facilitate substrate mapping in a WAVE configuration (WAVE). The purpose of this study was to determine the relative importance of the WAVE configuration compared to the STANDARD linear-only bipolar configuration (STANDARD) in defining VT substrate. METHODS: Thirteen patients underwent VT ablation at our institution. In all cases, a substrate map was constructed with the HD GRID in the WAVE configuration (conWAVE) to guide ablation strategy. At the end of the procedure, the voltage map was remapped in the STANDARD configuration (conSTANDARD) using the turbo-map function. Detailed post-hoc analysis of the WAVE and STANDARD maps was performed blinded to the configuration. Quantification of total scar area, BZ and dense scar area with assessment of conduction channels (CC) was performed. RESULTS: The substrate maps conSTANDARD vs conWAVE showed statistically significant differences in the total scar area (56 ± 32 cm2 vs 51 ± 30 cm2; p = 0.035), dense scar area (36 ± 25 cm2 vs 29 ± 22 cm2; p = 0.002) and number of CC (3.3 ± 1.6 vs 4.8 ± 2.5; p = 0.026). conWAVE collected more points than the conSTANDARD settings (p = 0.001); however, it used fewer points in map construction (p = 0.023). CONCLUSIONS: The multipolar Advisor™ HD Grid Mapping Catheter in conWAVE provides more efficient point acquisition and greater VT substrate definition of the borderzone particularly at the low-voltage range compared to conSTANDARD. This greater resolution within the low-voltage range facilitated CC definition and quantification within the scar, which is essential in guiding the ablation strategy.

Long-term follow-up of normal and structural heart ventricular tachycardia catheter ablation: real-world experience from a UK tertiary centre.

Background: Ventricular tachycardia (VT) is associated with increased morbidity and mortality. There is growing evidence for the effectiveness of catheter ablation in improving outcomes in patients with recurrent VT. Consequently the threshold for referral for VT ablation has fallen over recent years, resulting in increased number of procedures. Objective: To evaluate the effectiveness and safety of VT ablation in a real-world tertiary centre setting. Methods: This is a prospective analysis of all VT ablation cases performed at University Hospital Coventry. Follow-up data were obtained from review of electronic medical records and patient interview. The primary endpoint for normal heart VT was death, cardiovascular hospitalisation and VT recurrence, and for structural heart VT was arrhythmic death, VT storm (>3 episodes within 24 hours) or appropriate shock. Results: Forty-seven patients underwent 53 procedures from January 2012 to January 2018. The mean age ±SD was 57±15 years, 68% were male, 81% were Caucasian and 66% were elective cases. The aetiology of VT included normal heart (49%), ischaemic cardiomyopathy (ICM, 36%), dilated cardiomyopathy (9%), hypertrophic cardiomyopathy (4%) and valvular heart disease (2%). Procedural success occurred in 83%, with six major complications. After a median follow-up of 231 days (lower quartile 133, upper quartile 631), the primary outcome occurred in 28% of patients. There were two non-arrhythmic deaths (4%). At a median follow-up of 193 days (129-468), the primary outcome occurred in 19% of patients with ICM, while VT storm/appropriate shocks occurred in three patients (17%). Conclusions: Our real-world registry confirms that VT ablation is safe, and is associated with high acute procedural success and long-term outcomes comparable with randomised controlled studies.

Voltage during atrial fibrillation is superior to voltage during sinus rhythm in localizing areas of delayed enhancement on magnetic resonance imaging: An assessment of the posterior left atrium in patients with persistent atrial fibrillation.

BACKGROUND: Bipolar electrogram voltage during sinus rhythm (VSR) has been used as a surrogate for atrial fibrosis in guiding catheter ablation of persistent atrial fibrillation (AF), but the fixed rate and wavefront characteristics present during sinus rhythm may not accurately reflect underlying functional vulnerabilities responsible for AF maintenance. OBJECTIVE: The purpose of this study was determine whether, given adequate temporal sampling, the spatial distribution of mean AF voltage (VmAF) better correlates with delayed-enhancement magnetic resonance imaging (MRI-DE)-detected atrial fibrosis than VSR. METHODS: AF was mapped (8 seconds) during index ablation for persistent AF (20 patients) using a 20-pole catheter (660 ± 28 points/map). After cardioversion, VSR was mapped (557 ± 326 points/map). Electroanatomic and MRI-DE maps were co-registered in 14 patients. RESULTS: The time course of VmAF was assessed from 1-40 AF cycles (∼8 seconds) at 1113 locations. VmAF stabilized with sampling >4 seconds (mean voltage error 0.05 mV). Paired point analysis of VmAF from segments acquired 30 seconds apart (3667 sites; 15 patients) showed strong correlation (r = 0.95; P <.001). Delayed enhancement (DE) was assessed across the posterior left atrial (LA) wall, occupying 33% ± 13%. VmAF distributions were (median [IQR]) 0.21 [0.14-0.35] mV in DE vs 0.52 [0.34-0.77] mV in non-DE regions. VSR distributions were 1.34 [0.65-2.48] mV in DE vs 2.37 [1.27-3.97] mV in non-DE. VmAF threshold of 0.35 mV yielded sensitivity of 75% and specificity of 79% in detecting MRI-DE compared with 63% and 67%, respectively, for VSR (1.8-mV threshold). CONCLUSION: The correlation between low-voltage and posterior LA MRI-DE is significantly improved when acquired during AF vs sinus rhythm. With adequate sampling, mean AF voltage is a reproducible marker reflecting the functional response to the underlying persistent AF substrate.

Cardiac resynchronization therapy and its role in the management of heart failure.

The prevalence of heart failure is increasing and it is associated with significant mortality and morbidity. Optimal medical therapy improves outcome, but heart failure continues to have a substantial impact on both the individual patient and wider society. Over the last two decades, cardiac resynchronization therapy has revolutionized the treatment of selected patients who have heart failure. Cardiac resynchronization therapy significantly reduces mortality and hospitalization through reverse cardiac remodelling. This review informs non-specialists about cardiac resynchronization therapy and for which patients it should be considered.

Respiration driven excessive sinus tachycardia treated with clonidine.

A 26-year-old man presented to our syncope service with debilitating daily palpitations, shortness of breath, presyncope and syncope following a severe viral respiratory illness 4 years previously. Mobitz type II block had previously been identified, leading to a permanent pacemaker and no further episodes of frank syncope. Transthoracic echocardiography, electophysiological study and repeated urine metanepherines were normal. His palpitations and presyncope were reproducible on deep inspiration, coughing, isometric hand exercise and passive leg raises. We demonstrated rapid increases in heart rate with no change in morphology on his 12 lead ECG. His symptoms were resistant to fludrocortisone, flecainide, ß blockers and ivabradine. Initiation of clonidine in combination with ivabradine led to rapid resolution of his symptoms. We suggest that an excessive respiratory sinus arrhythmia was responsible for his symptoms and achieved an excellent response with the centrally acting sympatholytic clonidine, where previous peripherally acting treatments had failed.

Visualizing Localized Reentry With Ultra-High Density Mapping in Iatrogenic Atrial Tachycardia: Beware Pseudo-Reentry.

BACKGROUND: The activation pattern of localized reentry (LR) in atrial tachycardia remains incompletely understood. We used the ultra-high density Rhythmia mapping system to study activation patterns in LR. METHODS AND RESULTS: LR was suggested by small rotatory activations (carousels) containing the full spectrum of the color-coded map. Twenty-three left-sided atrial tachycardias were mapped in 15 patients (age: 64±11 years). 16 253±9192 points were displayed per map, collected over 26±14 minutes. A total of 50 carousels were identified (median 2; quartiles 1-3 per map), although this represented LR in only n=7 out of 50 (14%): here, rotation occurred around a small area of scar (<0.03 mV; 12±6 mm diameter). In LR, electrograms along the carousel encompassed the full tachycardia cycle length, and surrounding activation moved away from the carousel in all directions. Ablating fractionated electrograms (117±18 ms; 44±13% of tachycardia cycle length) within the carousel interrupted the tachycardia in every LR case. All remaining carousels were pseudo-reentrant (n=43/50 [86%]) occurring in areas of wavefront collision (n=21; median 0.5; quartiles 0-2 per map) or as artifact because of annotation of noise or interpolation in areas of incomplete mapping (n=22; median 1, quartiles 0-2 per map). Pseudo-reentrant carousels were incorrectly ablated in 5 cases having been misinterpreted as LR. CONCLUSIONS: The activation pattern of LR is of small stable rotational activations (carousels), and this drove 30% (7/23) of our postablation atrial tachycardias. However, this appearance is most often pseudo-reentrant and must be differentiated by interpretation of electrograms in the candidate circuit and activation in the wider surrounding region.

The changing face of cardiovascular disease 2000-2012: An analysis of the world health organisation global health estimates data.

The pattern and global burden of disease has evolved considerably over the last two decades, from primarily communicable, maternal, and perinatal causes to non-communicable disease (NCD). Cardiovascular disease (CVD) has become the single most important and largest cause of NCD deaths worldwide at over 50%. The World Health Organisation (WHO) estimates that 17.6 million people died of CVD worldwide in 2012. Proportionally, this accounts for an estimated 31.43% of global mortality, with ischaemic heart disease (IHD) accounting for approximately 7.4 million deaths, 13.2% of the total. IHD was also the greatest single cause of death in 2000, accounting for an estimated 6.0 million deaths. The global burden of CVD falls, principally, on the low and middle-income (LMI) countries, accounting for over 80% of CVD deaths. Individual populations face differing challenges and each population has unique health burdens, however, CVD remains one of the greatest health challenges both nationally and worldwide.

A Prospective Study of Ripple Mapping the Post-Infarct Ventricular Scar to Guide Substrate Ablation for Ventricular Tachycardia.

BACKGROUND: Post-infarct ventricular tachycardia is associated with channels of surviving myocardium within scar characterized by fractionated and low-amplitude signals usually occurring late during sinus rhythm. Conventional automated algorithms for 3-dimensional electro-anatomic mapping cannot differentiate the delayed local signal of conduction within the scar from the initial far-field signal generated by surrounding healthy tissue. Ripple mapping displays every deflection of an electrogram, thereby providing fully informative activation sequences. We prospectively used CARTO-based ripple maps to identify conducting channels as a target for ablation. METHODS AND RESULTS: High-density bipolar left ventricular endocardial electrograms were collected using CARTO3v4 in sinus rhythm or ventricular pacing and reviewed for ripple mapping conducting channel identification. Fifteen consecutive patients (median age 68 years, left ventricular ejection fraction 30%) were studied (6 month preprocedural implantable cardioverter defibrillator therapies: median 19 ATP events [Q1-Q3=4-93] and 1 shock [Q1-Q3=0-3]). Scar (<1.5 mV) occupied a median 29% of the total surface area (median 540 points collected within scar). A median of 2 ripple mapping conducting channels were seen within each scar (length 60 mm; initial component 0.44 mV; delayed component 0.20 mV; conduction 55 cm/s). Ablation was performed along all identified ripple mapping conducting channels (median 18 lesions) and any presumed interconnected late-activating sites (median 6 lesions; Q1-Q3=2-12). The diastolic isthmus in ventricular tachycardia was mapped in 3 patients and colocated within the ripple mapping conducting channels identified. Ventricular tachycardia was noninducible in 85% of patients post ablation, and 71% remain free of ventricular tachycardia recurrence at 6-month median follow-up. CONCLUSIONS: Ripple mapping can be used to identify conduction channels within scar to guide functional substrate ablation.