Emergency out-of-hours catheter ablation for ventricular arrhythmia storm: a UK and Australian experience.

AIMS: There are limited data on emergency catheter ablation (CA) for ventricular arrhythmia (VA) storm. We describe the feasibility and safety of performing emergency CA in an out-of-hours setting for VA storm refractory to medical therapy at 2 tertiary hospitals. METHODS AND RESULTS: Twenty-five consecutive patients underwent out-of-hours (5pm-8am [weekday] or Friday 5pm-Monday 8am [weekend]) CA for VA storm refractory to anti-arrhythmic drugs and sedation. Baseline and procedural characteristics along with outcomes were compared to 91 consecutive patients undergoing weekday daytime-hours (8am-5pm) CA for VA storm. More patients undergoing out-of-hours CA had a left ventricular ejection fraction ≤35% (68% vs. 42%, P = 0.022), chronic kidney disease (60% vs. 20%, P < 0.001), and presented following a resuscitated out-of-hospital cardiac arrest (56% vs. 5%, P < 0.001), compared to the daytime-hours group. During median follow-up (377 [interquartile range 138-826] days), both groups experienced similar survival free from recurrent VA and VA storm. Survival free from cardiac transplant and/or mortality was lower in the out-of-hours group (44% vs. 81%, P = 0.007), but out-of-hours CA was not independently associated with increased cardiac transplant and/or mortality (hazard ratio 1.34, 95% confidence interval 0.61-2.96, P = 0.47). Of the 11 patients in the out-of-hours group who survived follow-up, VA-free survival was 91% and VA storm-free survival was 100% at 1-year after CA. CONCLUSION: Out-of-hours CA may occasionally be required to control VA storm and can be safe and efficacious in this scenario. During follow-up, cardiac transplant and/or mortality is common but undergoing out-of-hours CA was not predictive of this composite endpoint.

Convergent approach to persistent atrial fibrillation ablation: long-term single-centre safety and efficacy.

Background: Efforts to maintain sinus rhythm in patients with persistent atrial fibrillation (PsAF) remain challenging, with suboptimal long-term outcomes. Methods: All patients undergoing convergent PsAF ablation at our centre were retrospectively analysed. The Atricure Epi-Sense® system was used to perform surgical radiofrequency ablation of the LA posterior wall followed by endocardial ablation. Results: A total of 24 patients underwent convergent PsAF ablation, and 21 (84%) of them were male with a median age of 63. Twelve (50%) patients were obese. In total, 71% of patients had a severely dilated left atrium, and the majority (63%) had preserved left ventricular function. All were longstanding persistent. Eighteen (75%) patients had an AF duration of >2 years. There were no endocardial procedure complications. At 36 months, all patients were alive with no new stroke/transient ischaemic attack (TIA). Freedom from documented AF at 3, 6, 12, 18, 24, and 36 months was 83%, 78%, 74%, 74%, 74%, and 61%, respectively. There were no major surgical complications, with five minor complications recorded comprising minor wound infection, pericarditic pain, and hernia. Conclusions: Our data suggest that convergent AF ablation is effective with excellent immediate and long-term safety outcomes in a real-world cohort of patients with a significant duration of AF and evidence of established atrial remodelling. Convergent AF ablation appears to offer a safe and effective option for those who are unlikely to benefit from existing therapeutic strategies for maintaining sinus rhythm, and further evaluation of this exciting technique is warranted. Our cohort is unique within the published literature both in terms of length of follow-up and very low rate of adverse events.

Bilateral cardiac sympathetic denervation for refractory arrhythmia in an individual with catecholaminergic polymorphic ventricular tachycardia associated with T-cell-mediated ganglionitis.

The individual in our case was troubled with difficult to control arrhythmia in the context of RYR2-mutation positive catecholaminergic polymorphic ventricular tachycardia (CPVT) despite medication. Recurrent implantable cardioverter defibrillator (ICD) shocks occurred for ventricular tachycardia (VT) and ventricular fibrillation (VF) as well as inappropriate shocks as a result of rapidly conducted atrial fibrillation (AF). Catheter ablation was effective in controlling these episodes of AF. Despite left cardiac sympathetic denervation, episodes of ventricular arrhythmia and subsequent ICD shocks persisted. Contralateral sympathetic cardiac denervation was subsequently undertaken, with histology suggesting T-cell mediated ganglionitis. 18 months on, there have been no further episodes of ventricular arrhythmia.

Importance of thorough investigation in a patient presenting with recurrent collapse and ST elevation.

There is increasing literature to suggest numerous subgroups of Brugada syndrome (BrS), including those with ST elevation in the lateral or inferior leads. We present a case of a patient presenting with recurrent collapse and inferior ST elevation degenerating to ventricular fibrillation and ultimately leading to a diagnosis of BrS.

Atrial Tachycardia Arising From the Crista Terminalis, Detailed Electrophysiological Features and Long-Term Ablation Outcomes.

OBJECTIVES: The goal of this study was to characterize, in detail, focal atrial tachycardia (AT) arising from the crista terminalis to investigate associations with other atrial arrhythmia and to define long-term ablation outcomes. BACKGROUND: The crista terminalis is known to be the most common site of origin for focal AT, but it is not well characterized. METHODS: This study retrospectively identified a total of 548 ablation procedures for AT performed at a single center over a 16-year period, of which 171 were arising from the crista terminalis. RESULTS: Compared with patients with other AT sites of origin, crista terminalis AT patients were older (57.3 vs. 47.3 years), more commonly female (72.9% vs. 59.1%), were more commonly associated with coexistent atrioventricular nodal re-entry tachycardia (17.1% vs. 9.7%), and were more likely to be inducible with programmed stimulation (81.5% vs. 58.9%). There was preferential conduction in the superior-inferior axis along the crista terminalis. Acute ablation success rate was high (92.2%) and improved significantly when three-dimensional mapping was used (98.5%). Recurrence in the first 12 months after a successful ablation was 9.7%. Only 2 patients developed atrial fibrillation over the long-term follow-up of >7 years. CONCLUSIONS: This large series characterized the clinical and electrophysiological features and immediate and long-term ablation outcomes for AT originating from the crista terminalis. Features of the tachycardia suggest that age-related localized remodeling of the crista terminalis causes a superficial endocardial zone of conduction slowing leading to re-entry. Ablation outcomes were good, with long-term freedom from atrial arrhythmia.

Ablation of Atrial Arrhythmias After the Atriopulmonary Fontan Procedure: Mechanisms of Arrhythmia and Outcomes.

OBJECTIVES: This study sought to describe atrial arrhythmia mechanisms, acute outcomes, and long-term arrhythmia burdens following catheter ablation in adult atriopulmonary (AP) Fontan patients. BACKGROUND: Atrial arrhythmias are a significant cause of morbidity and mortality in the AP Fontan population. METHODS: Sixty consecutive atrial arrhythmia ablations were reviewed in 42 AP Fontan patients (31 ± 8 years of age), performed between 1998 and 2017. The number of induced and ablated tachycardias was recorded for each case, as well as the ability to ablate the suspected clinical tachycardia. Longer-term arrhythmia burden was assessed by using a 12-point clinical arrhythmia severity score. RESULTS: Intra-atrial re-entrant tachycardia (IART) was induced in 93% of cases (n = 56), atrioventricular re-entrant tachycardia in 2 (3%) and atrioventricular nodal re-entrant tachycardia in a single case. The mean number of tachycardias induced per case was 2.3. The critical isthmus for IART was mapped to the lateral (n = 10), inferolateral (n = 8), posterior/posterolateral (n = 16), or septal (n = 10) systemic venous atrium, or to the pulmonary venous atrium (n = 4). Ablation of all inducible tachycardias was achieved in 62%, ablation of at least one (but not all) inducible tachycardias in 25%, with failure to ablate any tachycardias in 13%. The suspected clinical arrhythmia was ablated in 50 cases (83%). Catheter ablation resulted in a significant reduction in arrhythmia score at 3 to 6, 12, and 24 months, irrespective of whether all inducible tachycardias were ablated, or the suspected clinical arrhythmia only. Twelve patients (29%) underwent at least one repeat ablation procedure, with a mean time between ablations of 2.7 ± 3.0 years. There were no cases of periprocedural death, stroke or cardiac tamponade. CONCLUSIONS: Catheter ablation can be a safe and effective intervention that will significantly reduce arrhythmia burden in the AP Fontan patient.

Fever in a returning traveller: visceral leishmaniasis triggering haemophagocytic lymphohistiocytosis.

We present the case of a 23-year-old student admitted with fever, night sweats and splenomegaly. These non-specific signs and symptoms posed a diagnostic challenge which was further complicated by a history of recent foreign travel. The range of potential diagnoses required a variety of investigations in order to reach the final diagnosis. The incidental finding of an incompetent bicuspid aortic valve and an inflamed gallbladder further clouded the diagnostic process. Despite treatment with broad spectrum antibiotics, the patient continued to deteriorate. Serological testing finally provided a diagnosis of visceral leishmaniasis. The patient subsequently developed haemophagocytic lymphohistiocytosis, a life-threatening immune hyperactivity state that very rarely complicates leishmaniasis infection. With the use of amphotericin B and high-dose steroids, the patient made an excellent recovery.

Isolation of the posterior left atrium for patients with persistent atrial fibrillation: routine adenosine challenge for dormant posterior left atrial conduction improves long-term outcome.

AIMS: Catheter ablation to achieve posterior left atrial wall (PW) isolation may be performed as an adjunct to pulmonary vein isolation (PVI) in patients with persistent atrial fibrillation (AF). We aimed to determine whether routine adenosine challenge for dormant posterior wall conduction improved long-term outcome. METHODS AND RESULTS: A total of 161 patients with persistent AF (mean age 59 ± 9 years, AF duration 6 ± 5 years) underwent catheter ablation involving circumferential PVI followed by PW isolation. Posterior left atrial wall isolation was performed with a roof and inferior wall line with the endpoint of bidirectional block. In 54 patients, adenosine 15 mg was sequentially administered to assess reconnection of the pulmonary veins and PW. Sites of transient reconnection were ablated and adenosine was repeated until no further reconnection was present. Holter monitoring was performed at 6 and 12 months to assess for arrhythmia recurrence. Posterior left atrial wall isolation was successfully achieved in 91% of 161 patients (procedure duration 191 ± 49 min, mean RF time 40 ± 19 min). Adenosine-induced reconnection of the PW was demonstrated in 17%. The single procedure freedom from recurrent atrial arrhythmia was superior in the adenosine challenge group (65%) vs. no adenosine challenge (40%, P < 0.01) at a mean follow-up of 19 ± 8 months. After multiple procedures, there was significantly improved freedom from AF between patients with vs. without adenosine PW challenge (85 vs. 65%, P = 0.01). CONCLUSION: Posterior left atrial wall isolation in addition to PVI is a readily achievable ablation strategy in patients with persistent AF. Routine adenosine challenge for dormant posterior wall conduction was associated with an improvement in the success of catheter ablation for persistent AF.

Long-term outcomes after first-onset arrhythmia in Fontan physiology.

OBJECTIVES: Patients living with a Fontan circulation are prone to develop arrhythmias. However, their prognostic impact has been seldom studied. As such, we aimed to determine the incidence and predictors of arrhythmias after the Fontan procedure and the long-term outcomes after the first onset of arrhythmias. METHODS: Of the 1034 patients who have undergone a Fontan procedure as recorded in the Australian and New Zealand Fontan Registry, we identified those in whom a tachyarrhythmia or bradyarrhythmia developed. We evaluated the incidence and predictors of developing arrhythmias and their prognostic impact on late outcomes. RESULTS: Arrhythmia developed in 195 patients. Tachyarrhythmia was present in 162 patients, bradyarrhythmia was present in 74 patients, and both forms were present in 41 patients. At 20 years, freedom from any arrhythmia, tachyarrhythmia, and bradyarrhythmia was 66% (95% confidence interval [CI], 59-72), 69% (95% CI, 62-75), and 85% (95% CI, 80-90), respectively. On multivariable analyses, patients with an extracardiac Fontan (hazard ratio [HR], 0.23; 95% CI, 0.10-0.51; P < .001) were less likely to develop an arrhythmia, whereas those with left atrial (HR, 3.18; 95% CI, 1.45-6.95; P = .004) and right atrial (HR, 4.00; 95% CI, 2.41-6.61; P < .001) isomerism were more likely to have an arrhythmia. After onset of any arrhythmia (tachyarrhythmia or bradyarrhythmia), 10- and 15-year survivals were 74% (65%-83%) and 70% (60%-80%), respectively, and freedom from Fontan failure was 55% (44%-64%) and 44% (32%-56%), respectively. The development of any arrhythmia (HR, 2.20; 95% CI, 1-44-3.34; P < .001), tachyarrhythmia (HR, 2.56; 95% CI, 1.60-4.11; P < .001), and bradyarrhythmia (HR, 1.85; 95% CI, 1.16-2.95; P = .01) were all independent predictors of late Fontan failure on multivariable analyses. CONCLUSIONS: The development of an arrhythmia is associated with a heightened risk of subsequent failure of the Fontan circulation.

Prolongation of atrio-ventricular node conduction in a rabbit model of ischaemic cardiomyopathy: Role of fibrosis and connexin remodelling.

Conduction abnormalities are frequently associated with cardiac disease, though the mechanisms underlying the commonly associated increases in PQ interval are not known. This study uses a chronic left ventricular (LV) apex myocardial infarction (MI) model in the rabbit to create significant left ventricular dysfunction (LVD) 8weeks post-MI. In vivo studies established that the PQ interval increases by approximately 7ms (10%) with no significant change in average heart rate. Optical mapping of isolated Langendorff perfused rabbit hearts recapitulated this result: time to earliest activation of the LV was increased by 14ms (16%) in the LVD group. Intra-atrial and LV transmural conduction times were not altered in the LVD group. Isolated AVN preparations from the LVD group demonstrated a significantly longer conduction time (by approximately 20ms) between atrial and His electrograms than sham controls across a range of pacing cycle lengths. This difference was accompanied by increased effective refractory period and Wenckebach cycle length, suggesting significantly altered AVN electrophysiology post-MI. The AVN origin of abnormality was further highlighted by optical mapping of the isolated AVN. Immunohistochemistry of AVN preparations revealed increased fibrosis and gap junction protein (connexin43 and 40) remodelling in the AVN of LVD animals compared to sham. A significant increase in myocyte-non-myocyte connexin co-localization was also observed after LVD. These changes may increase the electrotonic load experienced by AVN muscle cells and contribute to slowed conduction velocity within the AVN.

Progression of atrial remodeling in patients with high-burden atrial fibrillation: Implications for early ablative intervention.

BACKGROUND: Advanced atrial remodeling predicts poor clinical outcomes in human atrial fibrillation (AF). OBJECTIVE: The purpose of this study was to define the magnitude and predictors of change in left atrial (LA) structural remodeling over 12 months of AF. METHODS: Thirty-eight patients with paroxysmal AF managed medically (group 1), 20 undergoing AF ablation (group 2), and 25 control patients with no AF history (group 3) prospectively underwent echocardiographic assessment of strain variables of LA reservoir function at baseline and at 4, 8, and 12 months. In addition, P-wave duration (Pmax,, Pmean) and dispersion (Pdis) were measured. AF burden was quantified by implanted recorders. Twenty patients undergoing ablation underwent electroanatomic mapping (mean 333 ± 40 points) for correlation with LA strain. RESULT: Group 1 demonstrated significant deterioration in total LA strain (26.3% ± 1.2% to 21.7% ± 1.2%, P < .05) and increases in Pmax (132 ± 3 ms to 138 ± 3 ms, P < .05) and Pdis (37 ± 2 ms to 42 ± 2 ms, P < .05). AF burden ≥10% was specifically associated with decline in strain and with P-wave prolongation. Conversely, group 2 manifest improvement in total LA strain (21.3% ± 1.7% to 28.6% ± 1.7%, P <.05) and reductions in Pmax (136 ± 4 ms to 119 ± 4 ms, P < .05) and Pdis (47 ± 3 ms to 32 ± 3 ms, P < .05). Change was not significant in group 3. LA mean voltage (r = 0.71, P = .0005), percent low voltage electrograms (r = -0.59, P = .006), percent complex electrograms (r = -0.68, P = .0009), and LA activation time (r = -0.69, P = .001) correlated with total strain as a measure of LA reservoir function. CONCLUSION: High-burden AF is associated with progressive LA structural remodeling. In contrast, AF ablation results in significant reverse remodeling. These data may have implications for timing of ablative intervention.

Acidosis slows electrical conduction through the atrio-ventricular node.

Acidosis affects the mechanical and electrical activity of mammalian hearts but comparatively little is known about its effects on the function of the atrio-ventricular node (AVN). In this study, the electrical activity of the epicardial surface of the left ventricle of isolated Langendorff-perfused rabbit hearts was examined using optical methods. Perfusion with hypercapnic Tyrode's solution (20% CO2, pH 6.7) increased the time of earliest activation (Tact) from 100.5 ± 7.9 to 166.1 ± 7.2 ms (n = 8) at a pacing cycle length (PCL) of 300 ms (37°C). Tact increased at shorter PCL, and the hypercapnic solution prolonged Tact further: at 150 ms PCL, Tact was prolonged from 131.0 ± 5.2 to 174.9 ± 16.3 ms. 2:1 AVN block was common at shorter cycle lengths. Atrial and ventricular conduction times were not significantly affected by the hypercapnic solution suggesting that the increased delay originated in the AVN. Isolated right atrial preparations were superfused with Tyrode's solutions at pH 7.4 (control), 6.8 and 6.3. Low pH prolonged the atrial-Hisian (AH) interval, the AVN effective and functional refractory periods and Wenckebach cycle length significantly. Complete AVN block occurred in 6 out of 9 preparations. Optical imaging of conduction at the AV junction revealed increased conduction delay in the region of the AVN, with less marked effects in atrial and ventricular tissue. Thus acidosis can dramatically prolong the AVN delay, and in combination with short cycle lengths, this can cause partial or complete AVN block and is therefore implicated in the development of brady-arrhythmias in conditions of local or systemic acidosis.

Pulmonary vein isolation: the impact of pulmonary venous anatomy on long-term outcome of catheter ablation for paroxysmal atrial fibrillation.

BACKGROUND: Circumferential pulmonary vein (PV) isolation is the cornerstone of catheter ablation for atrial fibrillation (AF); however, PV reconnection remains problematic. OBJECTIVE: To assess the impact of PV anatomy on outcome after AF ablation. METHODS: One hundred two patients with paroxysmal AF underwent cardiac magnetic resonance (60%) or computed tomography (40%) before AF ablation. PV anatomy was classified according to the presence of common PVs, accessory PVs, PV branching pattern, and the dimensions of the PV ostia, intervenous ridges (IVRs), and the left PV-left atrial appendage ridge. RESULTS: Four discrete PVs were present in 48(47%) of the patients: a left common PV in 38(37%), a right common PV in 2(2%), an accessory right PV in 20(20%), and left PV in 4(4%). At a mean follow-up of 12 ± 4 months, 75 of 102 (74%) patients were free of recurrent AF. A LCPV was associated with an increase in freedom from AF (87% vs 66% for 4 PV anatomy; P = .03). Greater left IVR length (16.9 ± 3.5 mm vs 14.0 ± 3.0 mm; P ≤ .001) and width (1.4 ± 0.6 mm vs 1.1 ± 0.6 mm; P = .02) were associated with increased AF recurrence. After multivariate analysis, abnormal anatomy (LCPV or accessory PV) and left IVR length were found to be the only independent predictors of freedom from AF. CONCLUSIONS: Four discrete PVs are present in the minority of patients with paroxysmal AF undergoing PV isolation. The presence of a LCPV is associated with an increased freedom from AF after catheter ablation. PV anatomy may in part explain the variable outcome to electrical isolation in patients with paroxysmal AF.