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.

Can C-Reactive Protein Be Used to Predict Acute Septic Arthritis in the Adult Population?

OBJECTIVES: The objective of this study was to establish whether C-reactive protein (CRP) could be used to predict native joint septic arthritis (SA) in the adult population. METHODS: All patients who underwent native joint aspiration in accident and emergency settings between April 2012 and September 2016 were identified from laboratory microbiology records. Patients were divided into three groups for analysis: patients with SA, patients with crystal arthropathy, and patients with normal or osteo/inflammatory arthritic joints. RESULTS: Fifteen patients (7.9%) were deemed to have SA, 18 patients had crystal arthropathy (9.5%), and 157 patients (82.6%) were deemed to have normal or osteo/inflammatory arthritic joints. All of the patients with CRP >200 mg/L had SA. Patients with CRP 90 to 200 mg/L had a mix of crystal arthropathy and SA, and patients with CRP <90 mg/L had either normal or osteo/inflammatory arthritic joints or crystal arthropathy. The mean CRP in patients with a normal or osteo/inflammatory arthritic joint was 25 mg/L. This was compared with 100 mg/L (P ≤ 0.001) in patients with crystal arthropathy and 308 mg/L (P ≤ 0.001) in patients with SA. CONCLUSIONS: We demonstrated CRP to be a reliable independent marker to help differentiate among SA, crystal arthropathy, and normal/arthritic joints in an adult population. No patients with CRP <90 mg/L had SA.

Increasing age does not affect time to appropriate therapy in primary prevention ICD/CRT-D: a competing risks analysis.

Aims: To evaluate the impact of age on the clinical outcomes in a primary prevention implantable cardioverter defibrillator (ICD)/cardiac resynchronization therapy defibrillator (CRT-D) population. Methods and Results: A retrospective, multicentre analysis of patients aged 60 years and over with primary prevention ICD/CRT-D devices implanted between 1 January 2006 and 1 November 2014 was performed. Survival to follow-up with no therapy (T1), death prior to follow-up with no therapy (T2), delivery of appropriate therapy with survival to follow-up (T3), and delivery of appropriate therapy with death prior to follow-up (T4) were measured. In total, 424 patients were eligible for inclusion in the analysis, mean follow-up of 32.6 months during which time 44 patients (10.1%) received appropriate therapy. The sub-hazard ratio (SHR) for the cumulative incidence of appropriate therapy (T3) according to age at implant was 1.00 (P = 0.851; 95% CI 0.96­1.04). The SHR for cumulative incidence of death (T2) according to age at implant was 1.06 (P < 0.001; 95% CI 1.03­1.01). Age at implant, ischaemic aetiology, baseline haemoglobin, and the presence of diabetes mellitus were predictors of all-cause mortality. Conclusion: Age has no impact on the time to appropriate therapy, but risk of death prior to therapy increases by 6% for every year increment. As the ICD population ages, the proportion who die without receiving appropriate therapy increases due to competing risks. Characterizing competing risks predictive of death independent of ICD indication would focus therapy on those with potential to benefit and reduce unnecessary exposure to ICD-related morbidity.

Safety and mid-term outcome of catheter ablation of ventricular tachycardia in octogenarians.

AIMS: Radiofrequency (RF) catheter ablation (CA) is superior to standard medical therapy in controlling recurrent ventricular tachycardia (VT). The majority of procedures have been performed in a middle-aged population. The outcome of VT ablation in the elderly has not been described. METHODS AND RESULTS: We retrospectively studied the outcome and safety of CA of VT in octogenarians performed in four European centres. The population consisted of patients presenting with recurrent VT refractory to medical therapy. Patients aged over 80 years were compared with younger patients undergoing CA. Clinical characteristics, procedural data, complications, and outcomes were examined. Implantable cardioverter-defibrillator (ICD) therapy data were collected. A total of 54 consecutive octogenarian patients underwent RF CA of VT and represented the study group (42 males, age 82.8 ± 2.7 years) compared with a control group of 104 younger patients (85 males, age 66.7 ± 8.9 years). Mean follow-up was 33 ± 48 months. Implantable cardioverter-defibrillators were present in 81 and 86% of patients, respectively (P = 0.93). Left ventricular ejection fraction was 29% ± 8.2 in octogenarians vs. 34% ± 10.2 in the younger group (P < 0.01). More major complications occurred in octogenarians (18 vs. 2%, P < 0.01). During follow-up, there were more ICD shocks in the octogenarians (28 vs. 15%, P < 0.01). The Kaplan-Meier curve of survival after VT ablation confirms comparable survival rates at 1 year, but the elderly have poor survival in the mid-term. Survival in the elderly post VT ablation is comparable with that in an age-matched cohort with ICDs but no VT storm. CONCLUSION: Octogenarians undergoing CA of VT have more risk factors, higher risk of complications and ICD shocks, but demonstrate comparable short-term survival rates.

Catheter ablation of atrial fibrillation in patients with heart failure: impact of maintaining sinus rhythm on heart failure status and long-term rates of stroke and death.

AIMS: Catheter ablation of atrial fibrillation (AF) in patients with heart failure (HF) can improve left ventricular (LV) function and HF symptoms. We aimed to investigate whether long-term maintenance of sinus rhythm impacts on hard outcomes such as stroke and death. METHODS AND RESULTS: An international multicentre registry was compiled from seven centres for consecutive patients undergoing catheter ablation of AF. Long-term freedom from AF was examined in patients with and without HF. The impact of maintaining sinus rhythm on rates of stroke and death was also examined. A total of 1273 patients were included: 171 with HF and 1102 without. Median follow-up was 3.1 years (IQR 2.0-4.3). The final procedure success rate was no different for paroxysmal AF (PAF) (78.7 vs. 85.7%, P = 0.186), but significantly different for persistent AF (57.3 vs. 75.8%, P < 0.001). Multivariate analysis showed that HF independently predicted recurrent arrhythmia [hazard ratio (HR) 1.7, 95% confidence interval (CI) 1.2-2.4, P = 0.002]. New York Heart Association class decreased from 2.3 ± 0.7 at baseline to 1.5 ± 0.8 at follow-up (P < 0.001). Left ventricular ejection fraction (LVEF) increased from 34.3 ± 9.0 to 45.8 ± 12.8% (P < 0.001). Recurrent AF was strongly predictive of stroke or death in HF patients (HR 8.33, 95% CI 1.86-37.7, P = 0.001). CONCLUSION: Long-term success rates for persistent (but not paroxysmal) AF ablation are significantly lower in HF patients. Left ventricular function and HF symptoms were improved following ablation. In HF patients, recurrent arrhythmia strongly predicted stroke and death during follow-up.

Catheter ablation of atrial fibrillation in patients with diabetes mellitus: a systematic review and meta-analysis.

AIMS: Diabetes mellitus (DM) and atrial fibrillation (AF) share pathophysiological links, as supported by the high prevalence of AF within DM patients. Catheter ablation of AF (AFCA) is an established therapeutic option for rhythm control in drug resistant symptomatic patients. Its efficacy and safety among patients with DM is based on small populations, and long-term outcome is unknown. The present systematic review and meta-analysis aims to assess safety and long-term outcome of AFCA in DM patients, focusing on predictors of recurrence. METHODS AND RESULTS: A systematic review was conducted in MEDLINE/PubMed and Cochrane Library. Randomized controlled trials, clinical trials, and observational studies including patients with DM undergoing AFCA were screened and included if matching inclusion and exclusion criteria. Fifteen studies were included, adding up to 1464 patients. Mean follow-up was 27 (20-33) months. Overall complication rate was 3.5 (1.5-5.0)%. Efficacy in maintaining sinus rhythm at follow-up end was 66 (58-73)%. Meta-regression analysis revealed that advanced age (P < 0.001), higher body mass index (P < 0.001), and higher basal glycated haemoglobin level (P < 0.001) related to higher incidence of arrhythmic recurrences. Performing AFCA lead to a reduction of patients requiring treatment with antiarrhythmic drugs (AADs) from 55 (46-74)% at baseline to 29 (17-41)% (P < 0.001) at follow-up end. CONCLUSIONS: Catheter ablation of AF safety and efficacy in DM patients is similar to general population, especially when performed in younger patients with satisfactory glycemic control. Catheter ablation of AF reduces the amount of patients requiring AADs, an additional benefit in this population commonly exposed to adverse effects of AF pharmacological treatments.

Demographic and Clinical Characteristics to Predict Paroxysmal Atrial Fibrillation: Insights from an Implantable Loop Recorder Population.

BACKGROUND: There is growing interest in detecting paroxysmal atrial fibrillation (PAF) to identify patients at high risk of thromboembolic stroke. The implantable loop recorder (ILR) is emerging as a powerful new tool in the diagnosis of PAF. Widespread implantation has significant cost implications and their use must be targeted at those patients at most risk. METHODS: We retrospectively studied a population of 200 adult patients who underwent ILR implantation for the investigation of syncope or palpitations. Clinical data, baseline electrocardiogram (ECG) characteristics, and echocardiographic data were collected. All ECGs and electrograms (EGMs) were scrutinized by two blinded investigators. PAF incidence was defined as episodes lasting >30 seconds on EGMs recorded in ILR memory. RESULTS: Our ILR population consists of 200 patients, 111 (56%) male, with a mean age of 61.4 years (range 19-95). PAF was detected in 42 patients. The following factors were significant predictors of PAF by multivariate logistic regression analysis: cigarette smoking (odds ratio [OR] = 3.73, 95% confidence interval [CI] = 1.40-10.24, P = 0.009) and incomplete right bundle branch block (IRBBB; OR = 9.04, 95% CI = 2.51-34.64, P = 0.00088). Significant differences included incidence of IRBBB (P = 0.012), cigarette smoking (P = 0.026), hypercholesterolemia (P = 0.015), age (P = 0.002), estimated glomerular filtration rate (P = 0.031), left atrial volume (P = 0.019), and PR interval (P = 0.031). The PAF group had significantly higher CHA2 DS2 -VASc scores (P = 0.01). CONCLUSIONS: Our study reports predictive factors for PAF in an ILR population. We suggest that cigarette smoking and IRBBB are independently associated with paroxysmal AF in patients presenting with palpitations or syncope.

Clinical Predictors of Pacemaker Implantation in Patients with Syncope Receiving Implantable Loop Recorder with or without ECG Conduction Abnormalities.

BACKGROUND: Implantable loop recorders (ILR) allow prolonged cardiac rhythm monitoring and improved diagnostic yield in syncope patients. Predictive factors for pacemaker (PM) implantation in the ILR population with unexplained syncope have not been adequately investigated. In this single center, retrospective, observational study we investigated factors that predict PM implantation in this population. METHODS: We retrospectively analyzed our ILR database of patients aged over 18 years who underwent ILR implantation for unexplained syncope between January 2009 and June 2013. Patient case notes were examined for demographics, history, electrocardiogram (ECG) abnormalities, investigations, and events during follow-up. The primary end-point was the detection of a symptomatic or asymptomatic bradycardia requiring PM implantation. RESULTS: During a period of 4.5 years, 200 patients were implanted with ILR for unexplained syncope, of who n = 33 (16.5%) had clinically significant bradycardia requiring PM implantation. After multivariable analysis, history of injury secondary to syncope was found to be the strongest independent predictor for PM implantation (odds ratio [OR]:9.1; P < 0.001; 95% confidence interval [CI]: (3.26-26.81). Other significant predictors included female sex, PR interval > 200msec, and age >75 years. In patients without conduction abnormalities on the ECG, history of injury secondary to syncope was found to be the strongest independent predictor for PM implantation (OR: 8.16; P = 0.00027; 95% [CI]: (2.67-26.27). CONCLUSIONS: A history of injury secondary to syncope and female sex were independent predictive factors for bradycardia necessitating PM implantation in patients receiving an ILR for syncope with or without ECG conduction abnormalities.

Development, implementation, and preliminary evaluation of a recovery-based curriculum for community navigation specialists working with individuals with serious mental illnesses and repeated hospitalizations.

A recovery-oriented curriculum for training the Community Navigation Specialists (CNSs) of the new Opening Doors to Recovery in Southeast Georgia program was developed, implemented, and preliminarily evaluated. This new mental health program provides mobile, community-based support services to individuals with serious mental illnesses and a history of psychiatric inpatient recidivism (and commonly past incarcerations and homelessness). Teams of CNSs include a licensed social worker, a family member of an individual with a serious mental illness, and a peer specialist with lived experience. In two courses held in February and June of 2011, 14 newly hired CNSs participated in the new training. A pre-training/post-training evaluation demonstrated statistically significant improvements in pertinent knowledge and self-efficacy for working in a community navigation role. As the recovery paradigm continues to be implemented in diverse real-world mental health treatment settings, recovery-based training curricula should be carefully constructed and evaluated.

Epicardial catheter ablation for ventricular tachycardia in heparinized patients.

AIMS: In patients undergoing epicardial catheter ablation of ventricular tachycardia (VT), current guidelines recommend obtaining pericardial access prior to heparinization to minimize bleeding complications. Consequently, access is obtained before endocardial mapping (leading to unnecessary punctures) or during an additional procedure. We present our experience of obtaining pericardial access during the index procedure in heparinized patients. METHODS AND RESULTS: Patients undergoing catheter ablation of VT in whom pericardial access was performed after heparinization were included. Clinical and procedural data and complications were recorded. Electrocardiograms (ECGs) were analysed for published criteria suggesting an epicardial ablation target and compared with patients (matched for substrate) undergoing successful endocardial ablation. Seventeen patients (13 males, age 58 ± 16 years, 8 (47%) ischaemic) were evaluated. Pericardial access was achieved in 16 (94%), including 2 patients with prior epicardial ablation. The mean activated clotting time was 273 ± 36 s. No bleeding complications occurred. In three patients, inadvertent puncture of the right ventricle caused no adverse consequences. An epicardial ablation target was found in nine of which three (33%) had ECG criteria, suggesting an epicardial circuit. In comparison 5 of 17 patients undergoing successful endocardial ablation had at least one ECG criterion suggesting an epicardial ablation target. CONCLUSION: Obtaining pericardial access for epicardial catheter ablation for VT appears to be safe in heparinized patients. Electrocardiogram criteria suggesting an epicardial ablation target lack the sensitivity and specificity accurately to predict which patients might need epicardial ablation. Performing pericardial access in heparinized patients therefore may reduce unnecessary punctures and reduce the number of additional procedures in some patients.

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.

Routine transthoracic echocardiography to assess pericardial collections in patients after extensive left atrial catheter ablation: a prospective study.

INTRODUCTION: Little is known about the incidence and timing of reactive pericardial collections developing after left atrial catheter ablation (LACA), and when and if transthoracic echocardiography (TTE) should be performed routinely in these patients postprocedure. METHODS AND RESULTS: Two hundred consecutive LACA patients for persistent atrial fibrillation (AF) (107), paroxysmal AF (75) or atrial tachycardia (AT) (18) underwent on-table TTE at the end of the procedure, and the next day prior to discharge. One patient developed tamponade at the time of transseptal puncture. Thirty-three percent of the remaining 199 who underwent on-table TTE, had a pericardial collection. On next day TTE, there were significantly more pericardial collections (53%, P < 0.0001). Persistent rather than paroxysmal arrhythmia at the time of the procedure was the only predictor of a pericardial collection, either on-table (χ(2)= 9.64; P = 0.002) or next day (χ(2)= 5.95; P = 0.02). Eight patients had collections on next day TTE ≥ 1.5 cm. One needed drainage because of clinical tamponade. Repeated TTEs in the other 7 patients demonstrated resolution of collections over 1-2 weeks. CONCLUSION: Pericardial collections are common in LACA patients. Almost all are not associated with clinical compromise. The only predictor of collection size is arrhythmia type at ablation, which may correspond to ablation at sites specific to persistent rather than paroxysmal arrhythmias. Performing on-table TTE routinely may help guide immediate anticoagulation protocols, but even larger on-table collections are not associated with tamponade and resolve spontaneously. TTE does not need to be performed routinely unless there are clinical signs of tamponade.

Uninterrupted warfarin for periprocedural anticoagulation in catheter ablation of typical atrial flutter: a safe and cost-effective strategy.

INTRODUCTION: Many patients undergoing catheter ablation of atrial flutter (AFL) require periprocedural anticoagulation. We compared a strategy of conversion to low molecular weight heparin (LMWH) periprocedure to uninterrupted warfarinization in a nonrandomized, case-controlled study. METHODS: One hundred and one consecutive patients requiring periprocedural anticoagulation for catheter ablation of typical AFL were studied. The first 51 patients underwent conversion to LMWH (enoxaparin 1 mg/kg bd) with a warfarin pause (LMWH group), the subsequent 50 continued with uninterrupted oral anticoagulation (Warfarin group). Primary endpoint was a composite of major and minor bleeding complications and groin symptoms. RESULTS: Fewer patients in the Warfarin group reached the primary endpoint (36.0% vs 56.8%, P = 0.013). Four patients in the LMWH group but no patient in the Warfarin group required hospital admission for bleeding-related complications. Cost analysis showed mean cost per patient of anticoagulation with LMWH to be pounds sterling 100.9 (95% CI 94.46-107.30) compared to pounds sterling 10.23 (4.49-15.97) in the Warfarin group (P < 0.0001). Transesophageal echocardiography (TEE) was performed prior to ablation in 11 patients in the Warfarin group and in 3 patients in the LMWH (P = 0.019). When TEE costs were included, costs were pounds sterling 125.00 ($188.25) (96.80-153.60) for the LMWH strategy and pounds sterling 108.5 ($163.40) (54.92-162.1) for the Warfarin group (P < 0.0001). CONCLUSIONS: Catheter ablation of typical AFL without interruption of warfarin appears safer and more cost-effective than periprocedural conversion to LMWH. It could be used as a routine anticoagulation strategy for the ablation of right-sided arrhythmias.

A prospective comparison of echocardiography and device algorithms for atrioventricular and interventricular interval optimization in cardiac resynchronization therapy.

AIMS: Echocardiographic optimization of atrioventricular (AV) and interventricular (VV) intervals in cardiac resynchronization therapy (CRT) is costly, time-consuming, and requires skill and expertise so is usually undertaken only in 'non-responder' patients. An algorithm in St Jude Medical CRT devices (QuickOpt) claims to optimize these settings automatically. The aim of this study was to compare the two optimization techniques. METHODS AND RESULTS: Optimization of AV and VV intervals was performed a month after CRT device implantation in 26 patients with heart failure, first by echocardiography then by QuickOpt. The left ventricular outflow tract (LVOT) velocity-time integral (VTI) was measured after optimization by each method. Agreement between the optimization methods was assessed by the Bland-Altman analysis and correlation by Pearson's correlation coefficient. There was good correlation between the LVOT VTI following optimization by both methods (R2 = 0.77, P < 0.001). However, agreement between the two methods was poor, with 15 of 26 and 10 of 26 patients having a >20 ms difference in the optimal AV and VV interval values, respectively. Left ventricular outflow tract VTI was significantly better (22 of 26 patients; P < 0.001) in patients optimized by echocardiography than by QuickOpt. CONCLUSION: There is a poor agreement in optimal AV and VV intervals determined by echocardiography and QuickOpt, with echocardiographic optimization giving a superior haemodynamic outcome.

Do traditional VT zones improve outcome in primary prevention ICD patients?

AIMS: We reviewed outcomes in our primary prevention implantable cardioverter defibrillator (ICD) population according to whether the device was programmed with a single ventricular fibrillation (VF) zone or with two zones including a ventricular tachycardia (VT) zone in addition to a VF zone. METHODS: This retrospective study examined 137 patients with primary prevention ICDs implanted at our institution between 2004 and 2006. Device programming and events during follow-up were reviewed. Outcomes included all-cause mortality, time to first shock, and incidence of shocks. RESULTS: Eighty-seven ICDs were programmed with a single VF zone (mean >193 ± 1 beats per minute [bpm]) comprising shocks only. Fifty ICDs had two zones (mean VT zone >171 ± 2 bpm; VF zone >205 ± 2 bpm), comprising antitachycardia pacing (100%), shocks (96%), and supraventricular (SVT) discriminators (98%) . Discriminator "time out" functions were disabled. Mean follow-up was 30 ± 0.5 months and similar in both groups. All-cause mortality (12.6% and 12.0%) and time to first shock were similar. However, the two-zone group received more shocks (32.0% vs 13.8% P = 0.01). Five of 16 shocks in these patients were inappropriate for SVT rhythms. The single-zone group had no inappropriate shocks for SVTs. Eighteen of 21 appropriate shocks were for ventricular arrhythmias at rates >200 bpm (three VF, 15 VT). This suggests that primary prevention ICD patients infrequently suffer ventricular arrhythmias at rates <200 bpm and that ATP may play a role in terminating rapid VTs. CONCLUSIONS: Patients with two-zone devices received more shocks without any mortality benefit.

Empirical correlation of triggered activity and spatial and temporal re-entrant substrates with arrhythmogenicity in a murine model for Jervell and Lange-Nielsen syndrome.

KCNE1 encodes the beta-subunit of the slow component of the delayed rectifier K(+) current. The Jervell and Lange-Nielsen syndrome is characterized by sensorineural deafness, prolonged QT intervals, and ventricular arrhythmogenicity. Loss-of-function mutations in KCNE1 are implicated in the JLN2 subtype. We recorded left ventricular epicardial and endocardial monophasic action potentials (MAPs) in intact, Langendorff-perfused mouse hearts. KCNE1 (-/-) but not wild-type (WT) hearts showed not only triggered activity and spontaneous ventricular tachycardia (VT), but also VT provoked by programmed electrical stimulation. The presence or absence of VT was related to the following set of criteria for re-entrant excitation for the first time in KCNE1 (-/-) hearts: Quantification of APD(90), the MAP duration at 90% repolarization, demonstrated alterations in (1) the difference, APD(90), between endocardial and epicardial APD(90) and (2) critical intervals for local re-excitation, given by differences between APD(90) and ventricular effective refractory period, reflecting spatial re-entrant substrate. Temporal re-entrant substrate was reflected in (3) increased APD(90) alternans, through a range of pacing rates, and (4) steeper epicardial and endocardial APD(90) restitution curves determined with a dynamic pacing protocol. (5) Nicorandil (20 microM) rescued spontaneous and provoked arrhythmogenic phenomena in KCNE1 (-/-) hearts. WTs remained nonarrhythmogenic. Nicorandil correspondingly restored parameters representing re-entrant criteria in KCNE1 (-/-) hearts toward values found in untreated WTs. It shifted such values in WT hearts in similar directions. Together, these findings directly implicate triggered electrical activity and spatial and temporal re-entrant mechanisms in the arrhythmogenesis observed in KCNE1 (-/-) hearts.

A randomized-controlled trial comparing conventional with minimal catheter approaches for the mapping and ablation of regular supraventricular tachycardias.

AIMS: To compare the use of a minimal (MIN) with a conventional (CON) catheter approach for the mapping and ablation of regular supraventricular tachycardias (SVT) and typical atrial flutter (AFL) in the setting of a randomized-controlled trial. METHODS AND RESULTS: Two hundred patients (age 51.2 +/- 15.9 years, 99 male) were randomized to a MIN or CON group. The MIN approach involved using two catheters for AFL, one to three for other SVT (ablation catheter included), whereas the CON approach involved three and five catheters, respectively. Acute procedural success was similar between the two groups. There was no significant difference in overall procedure times, fluoroscopy times, or radiation doses. Procedure times were shorter for AFL ablation in MIN compared with CON [60 (30-150) vs. 85 (40-200) min, median (range), P = 0.03] from subgroup analysis. A median of three (one to six) catheters was used in MIN and five (three to seven) in CON (P < 0.0001). Catheter costs were significantly lower in MIN compared with CON [6.1 (2-61) vs. 8.5 (4.4-21.3) units, P < 0.0001, where one unit is equivalent to the cost of a diagnostic quadripolar catheter]. At 6-week follow-up, two patients in MIN (2.1%) and three patients in CON (3.2%) had documented recurrence of the index arrhythmia. CONCLUSION: The use of a MIN approach in the treatment of SVT and AFL is as effective, quick, and safe as using a CON approach and is therefore more cost-effective.

A randomized trial to compare atrial fibrillation ablation using a steerable vs. a non-steerable sheath.

AIMS: Catheter positioning and stability are recognized challenges in catheter ablation of atrial fibrillation (AF). This prospective randomized study assessed whether routinely using a steerable sheath affects procedure outcomes. METHODS AND RESULTS: Fifty-six AF patients were randomized to ablation using either an Agilis NXT (St Jude Medical, St Paul, MN, USA) steerable sheath or a fixed-curve Mullins sheath (Cook Medical Inc., Bloomington, IN, USA) for the ablation catheter. A mapping system with CT integration was used to isolate the pulmonary veins (PVs) in pairs and further ablation performed if AF persisted. There was no significant difference in time to gain trans-septal access, CT registration time, time to isolate PVs, fluoroscopy time for PV isolation, total procedure time, or total fluoroscopy time. A learning curve was seen for the steerable sheath, and after correcting for this, CT registration time and right PV isolation were quicker in this group. One patient crossed over from fixed-curve to steerable. Acute, 3-, and 6-month single procedure success were similar in both groups. CONCLUSION: Allowing for the usage learning curve, a steerable sheath reduced time for some elements of AF ablation. Although this did not result in improved success, it may be useful for inexperienced operators, but at increased procedure cost.

Validation of a classification system to grade fractionation in atrial fibrillation and correlation with automated detection systems.

AIMS: We tested application of a grading system describing complex fractionated electrograms (CFE) in atrial fibrillation (AF) and used it to validate automated CFE detection (AUTO). METHODS AND RESULTS: Ten seconds bipolar electrograms were classified by visual inspection (VI) during ablation of persistent AF and the result compared with offline manual measurement (MM) by a second blinded operator: Grade 1 uninterrupted fractionated activity (defined as segments > or =70 ms) for > or =70% of recording and uninterrupted > or =1 s; Grade 2 interrupted fractionated activity > or =70% of recording; Grade 3 intermittent fractionated activity 30-70%; Grade 4 discrete (<70 ms) complex electrogram (> or =5 direction changes); Grade 5 discrete simple electrograms (< or =4 direction changes); Grade 6 scar. Grade by VI and MM for 100 electrograms agreed in 89%. Five hundred electrograms were graded on Carto and NavX by VI to validate AUTO in (i) detection of CFE (grades 1-4 considered CFE), and (ii) assessing degree of fractionation by correlating grade and score by AUTO (data shown as sensitivity, specificity, r): NavX 'CFE mean' 92%, 91%, 0.56; Carto 'interval confidence level' using factory settings 89%, 62%, -0.72, and other published settings 80%, 74%, -0.65; Carto 'shortest confidence interval' 74%, 70%, 0.43; Carto 'average confidence interval' 86%, 66%, 0.53. CONCLUSION: Grading CFE by VI is accurate and correlates with AUTO.

Validation of computed tomography image integration into the EnSite NavX mapping system to perform catheter ablation of atrial fibrillation.

INTRODUCTION: The complex anatomy of the left atrium (LA) makes location of ablation catheters difficult using fluoroscopy alone, and therefore 3D mapping systems are now routinely used. We describe the integration of a CT image into the EnSite NavX System with Fusion and its validation in patients undergoing atrial fibrillation (AF) or left atrial tachycardia (AT) catheter ablation. METHODS AND RESULTS: Twenty-three patients (61 +/- 9.2 years, 16 male) with paroxysmal (14) and persistent (8) AF and persistent (1) AT underwent ablation using CT image integration into the EnSite NavX mapping system with the EnSite Fusion Dynamic Registration software module. In all cases, segmentation of the CT data was accomplished using the EnSite Verismo segmentation tool, although repeat segmentation attempts were required in seven cases. The CT was registered with the NavX-created geometry using an average of 24 user-defined fiducial pairs (range 9 to 48). The average distance from NavX-measured lesion positions to the CT surface was 3.2 +/- 0.9 mm (median 2.4 mm). A large, automated, retrospective test using registrations with random subsets of each patient's fiducial pairs showed this average distance decreasing as the number of fiducial pairs increased, although the improvement ceased to be significant beyond 15 pairs. In confirmation, those studies which had used 16 or more pairs had a smaller average lesion-to-surface distance (2.9 +/- 0.7 mm) than those using 15 or fewer (4.3 +/- 0.8 mm, P < 0.02). Finally, for the 13 patients who underwent left atrial circumferential ablation (LACA), there was no significant difference between the circumference computed using NavX-measured positions and CT surface positions for either the left pulmonary veins (178 +/- 64 vs. 177 +/- 60 mm; P = 0.81) or the right pulmonary veins (218 +/- 86 vs. 207 +/- 81 mm; P = 0.08). CONCLUSION: CT image integration into the EnSite NavX Fusion system was successful in all patients undergoing catheter ablation. A learning curve exists for the Verismo segmentation tool; but once the 3D model was created, the registration process was easily accomplished, with a registration error that is comparable with registration errors using other mapping systems with CT image integration. All patients went on to have subsequent successful ablation procedures. Where LACA was performed (13 patients), only four patients required segmental ostial lesions to achieve electrical isolation.