Multi-catheter cryotherapy for the treatment of resistant accessory pathways.

OBJECTIVE: To investigate the utility of simultaneous multi-catheter cryotherapy for the treatment of APs that were previously resistant to standard radiofrequency (RF) catheter ablation. BACKGROUND: Catheter ablation is established in the treatment of accessory pathways (AP), with high rates of permanent procedural success with a single attempt. However, there are still instances of acute procedural failure and AP recurrences with standard RF and cryotherapy methods. METHODS: Seven consecutive cases of pre-excitation syndromes with prior failed RF catheter ablation had the novel treatment. Cryotherapy was delivered using two 8 mm tip focal cryoablation catheters (Freezor® Max, Medtronic, Minneapolis, Minnesota, USA). RESULTS: Accessory pathway localisation was septal in 5 cases, left posterolateral in 1, right lateral in 1. In all cases, ablation of the AP was acutely successful with no procedural complications. Median procedure and fluoroscopy durations were 199 and 35 min, sequentially. Median Procedure duration fell significantly in the second half of series (174 min) compared to the first half (233 min, P = 0.05). One patient had evidence of a recurring AP conduction with pre-excitation at 5-week follow up. After a median follow up of 66.8+-6.5 months, 6 out of 7 patients remained asymptomatic and free of pre-excitation. CONCLUSION: Simultaneous multi-catheter cryotherapy is feasible, safe and can provide definitive cure of accessory pathways that were previously resistant to standard radiofrequency ablation. Further study is required in the assessment of this novel form of advanced cryotherapy to treat complex and resistant arrhythmias.

Multi-lead cephalic venous access and long-term performance of high-voltage leads.

BACKGROUND: Cardiac resynchronization therapy-defibrillator (CRT-D) implantation via the cephalic vein is feasible and safe. Recent evidence has suggested a higher implantable cardioverter-defibrillator (ICD) lead failure in multi-lead defibrillator therapy via the cephalic route. We evaluated the relationship between CRT-D implantation via the cephalic and ICD lead failure. METHODS: Data was collected from three CRT-D implanting centers between October 2008 and September 2017. In total 633 patients were included. Patient and lead characteristics with ICD lead failure were recorded. Comparison of "cephalic" (ICD lead via cephalic) versus "non-cephalic" (ICD lead via non-cephalic route) cohorts was performed. Kaplan-Meier survival and a Cox-regression analysis were applied to assess variables associated with lead failure. RESULTS: The cephalic and non-cephalic cohorts were equally male (81.9% vs. 78%; p = .26), similar in age (69.7 ± 11.5 vs. 68.7 ± 11.9; p = .33) and body mass index (BMI) (27.7 ± 5.1 vs. 27.1 ± 5.7; p = .33). Most ICD leads were implanted via the cephalic vein (73.5%) and patients had a mean of 2.9 ± 0.28 leads implanted via this route. The rate of ICD lead failure was low and statistically similar between both groups (0.36%/year vs. 0.13%/year; p = .12). Female gender was more common in the lead failure cohort than non-failure (55.6% vs. 17.9%, respectively; p = .004) as was hypertension (88.9% vs. 54.2%, respectively, p = .038). On multivariate Cox-regression, female sex (p = .008; HR, 7.12 [1.7-30.2]), and BMI (p = .047; HR, 1.12 [1.001-1.24]) were significantly associated with ICD lead failure. CONCLUSION: CRT-D implantation via the cephalic route is not significantly associated with premature ICD lead failure. Female gender and BMI are predictors of lead failure.

Multi-catheter cryotherapy compared with radiofrequency ablation in long-standing persistent atrial fibrillation: a randomized clinical trial.

AIMS: Restoring sinus rhythm (SR) by ablation alone is an endpoint used in radiofrequency (RF) ablation for long-standing persistent atrial fibrillation (AF) but not with cryotherapy. The simultaneous use of two cryotherapy catheters can improve ablation efficiency; we compared this with RF ablation in chronic persistent AF aiming for termination to SR by ablation alone. METHODS AND RESULTS: Consecutive patients undergoing their first ablation for persistent AF of >6 months duration were screened. A total of 100 participants were randomized 1:1 to multi-catheter cryotherapy or RF. For cryotherapy, a 28-mm Arctic Front Advance was used in tandem with focal cryoablation catheters. Open-irrigated, non-force sensing catheters were used in the RF group with a 3D mapping system. Pulmonary vein (PV) isolation and non-PV triggers were targeted. Participants were followed up at 6 and 12 months, then yearly. Acute PVI was achieved in all cases. More patients in the multi-catheter cryotherapy group were restored to SR by ablation alone, with a shorter procedure duration. Sinus rhythm continued to the last available follow-up in 16/49 patients (33%) in the multi-catheter at 3.0 ± 1.6 years post-ablation and in 12/50 patients (24%) in the RF group at 4.0 ± 1.2 years post-ablation. The yearly rate of arrhythmia recurrence was similar. CONCLUSION: Multi-catheter cryotherapy can restore SR by ablation alone in more cases and more quickly than RF ablation. Long-term success is difficult to achieve by either methods and is similar with both.

Randomized comparison of oesophageal protection with a temperature control device: results of the IMPACT study.

AIMS: Thermal injury to the oesophagus is an important cause of life-threatening complication after ablation for atrial fibrillation (AF). Thermal protection of the oesophageal lumen by infusing cold liquid reduces thermal injury to a limited extent. We tested the ability of a more powerful method of oesophageal temperature control to reduce the incidence of thermal injury. METHODS AND RESULTS: A single-centre, prospective, double-blinded randomized trial was used to investigate the ability of the ensoETM device to protect the oesophagus from thermal injury. This device was compared in a 1:1 randomization with a control group of standard practice utilizing a single-point temperature probe. In the protected group, the device maintained the luminal temperature at 4°C during radiofrequency (RF) ablation for AF under general anaesthesia. Endoscopic examination was performed at 7 days post-ablation and oesophageal injury was scored. The patient and the endoscopist were blinded to the randomization. We recruited 188 patients, of whom 120 underwent endoscopy. Thermal injury to the mucosa was significantly more common in the control group than in those receiving oesophageal protection (12/60 vs. 2/60; P = 0.008), with a trend toward reduction in gastroparesis (6/60 vs. 2/60, P = 0.27). There was no difference between groups in the duration of RF or in the force applied (P value range= 0.2-0.9). Procedure duration and fluoroscopy duration were similar (P = 0.97, P = 0.91, respectively). CONCLUSION: Thermal protection of the oesophagus significantly reduces ablation-related thermal injury compared with standard care. This method of oesophageal protection is safe and does not compromise the efficacy or efficiency of the ablation procedure.

Exclusively cephalic venous access for cardiac resynchronisation: A prospective multi-centre evaluation.

BACKGROUND: Small series has shown that cardiac resynchronisation therapy (CRT) can be achieved in a majority of patients using exclusively cephalic venous access. We sought to determine whether this method is suitable for widespread use. METHODS: A group of 19 operators including 11 trainees in three pacing centres attempted to use cephalic access alone for all CRT device implants over a period of 8 years. The access route for each lead, the procedure outcome, duration, and complications were collected prospectively. Data were also collected for 105 consecutive CRT device implants performed by experienced operators not using the exclusively cephalic method. RESULTS: A new implantation of a CRT device using exclusively cephalic venous access was attempted in 1091 patients (73.6% male, aged 73 ± 12 years). Implantation was achieved using cephalic venous access alone in 801 cases (73.4%) and using a combination of cephalic and other access in a further 180 (16.5%). Cephalic access was used for 2468 of 3132 leads implanted (78.8%). Compared to a non-cephalic reference group, complications occurred less frequently (69/1091 vs 12/105; P = .0468), and there were no pneumothoraces with cephalic implants. Procedure and fluoroscopy duration were shorter (procedure duration 118 ± 45 vs 144 ± 39 minutes, P < .0001; fluoroscopy duration 15.7 ± 12.9 vs 22.8 ± 12.2 minutes, P < .0001). CONCLUSIONS: CRT devices can be implanted using cephalic access alone in a substantial majority of cases. This approach is safe and efficient.

The importance of dyslipidaemia in the pathogenesis of cardiovascular disease in people with diabetes.

Atherosclerotic cardiovascular events are the leading cause of mortality and morbidity in those with diabetes. A key contributor to the development of atherosclerosis in this population is the presence of a particularly atherogenic lipid profile often referred to as 'Diabetic Dyslipidemia'. This profile is characterized by elevated triglycerides, triglyceride-rich lipoproteins, small dense LDL particles, and reduced HDL levels. This article reviews the underlying aetiology and pathophysiology of this dyslipidaemia and atherosclerosis in those with diabetes, provides insights from epidemiological and genetic studies, and current cardiovascular risk reducing interventions including novel therapies such as PCSK-9 inhibitors.

A novel approach to mapping the atrial ganglionated plexus network by generating a distribution probability atlas.

INTRODUCTION: The ganglionated plexuses (GPs) of the intrinsic cardiac autonomic system are implicated in arrhythmogenesis. GP localization by stimulation of the epicardial fat pads to produce atrioventricular dissociating (AVD) effects is well described. We determined the anatomical distribution of the left atrial GPs that influence atrioventricular (AV) dissociation. METHODS AND RESULTS: High frequency stimulation was delivered through a Smart-Touch catheter in the left atrium of patients undergoing atrial fibrillation (AF) ablation. Three dimensional locations of points tested throughout the entire chamber were recorded on the CARTO™ system. Impact on the AV conduction was categorized as ventricular asystole, bradycardia, or no effect. CARTO maps were exported, registered, and transformed onto a reference left atrial geometry using a custom software, enabling data from multiple patients to be overlaid. In 28 patients, 2108 locations were tested and 283 sites (13%) demonstrated (AVD-GP) effects. There were 10 AVD-GPs (interquartile range, 11.5) per patient. Eighty percent (226) produced asystole and 20% (57) showed bradycardia. The distribution of the two groups was very similar. Highest probability of AVD-GPs (>20%) was identified in: inferoseptal portion (41%) and right inferior pulmonary vein base (30%) of the posterior wall, right superior pulmonary vein antrum (31%). CONCLUSION: It is feasible to map the entire left atrium for AVD-GPs before AF ablation. Aggregated data from multiple patients, producing a distribution probability atlas of AVD-GPs, identified three regions with a higher likelihood for finding AVD-GPs and these matched the histological descriptions. This approach could be used to better characterize the autonomic network.

Initial clinical results with the ThermoCool® SmartTouch® Surround Flow catheter.

AIM: The Biosense Webster ThermoCool® SmartTouch® Surround Flow (STSF) catheter is a recently developed ablation catheter incorporating Surround Flow (SF) technology to ensure efficient cooling and force sensing to quantify tissue contact. In our unit, it superseded the ThermoCool® SF catheter from the time of its introduction in May 2015. METHODS AND RESULTS: Procedure-related data were collected prospectively for the first 100 ablation procedures performed in our department using the STSF catheter. From a database of 654 procedures performed in our unit using the SF catheter, we selected one to match each STSF procedure, matching for procedure type, operator experience, patient age, and gender. The groups were well matched for patient age, gender, and procedure type. Procedure duration was similar in both groups (mean 225.5 vs. 221.4 min, IQR 106.5 vs. 91.5, P = 0.55), but fluoroscopy duration was shorter in the STSF group (mean 25.8 vs. 30.0, IQR 19.6 vs. 18.5, P = 0.03). No complication occurred in the STSF group. Complications occurred in two cases in the SF group (one pericardial effusion requiring drainage and one need for permanent pacing). Complete procedural success was achieved in 98 cases in the STSF group and 94 cases in the SF group (P = 0.15). The composite endpoint of procedure failure or acute complication was less common in the STSF group (2 vs. 8, P = 0.05). CONCLUSION: The STSF catheter is safe and effective in treating a range of arrhythmias. Compared with the SF catheter, it shows a trend towards improved safety-efficacy balance.

Non-laser percutaneous extraction of pacemaker and defibrillation leads: a decade of progress.

AIMS: Non-laser-based methods are safe in lead extraction but in the past have been less effective than laser methods. In the past decade, new equipment has been introduced including the Evolution® Mechanical Dilator Sheath and the Evolution® RL. We sought to determine the impact of new equipment on outcome in mechanical lead extraction. METHODS AND RESULTS: We considered 288 consecutive patients (age 66 ± 18 years) who underwent transvenous lead extraction (TLE) of 522 leads in the decade to the end of 2014. Three groups were identified: Group 1 (pre-Evolution® period, 76 patients, 133 leads), Group 2 (original Evolution® period, 115 patients, 221 leads), and Group 3 (Evolution® RL period, 97 patients, 168 leads). The age of leads was significantly greater in Groups 2 and 3 (6.2 ± 4.4 and 6.1 ± 5.4 years vs.4.7 ± 4.5, P < 0.05) as was the proportion of implantable cardioverter defibrillator leads (27.2 and 28.9 vs. 14.3%, P < 0.05). The groups were similar in the number of leads extracted per patient. Despite the increasing complexity of the systems extracted, complete extraction was achieved in a progressively greater proportion of leads (88.0% in Group 1, 95.5% in Group 2, and 97.6% in Group 3, P < 0.05), and procedure duration was similar. The proportion of leads for which femoral access was required was greater in Group 3 (11%, 18/164) compared with Group 2 (3%, 7/211), P = 0.006. The only major complications were a post-procedure subacute tamponade in Group 1 and an oesophageal injury related to transoesophageal echocardiography in Group 3. CONCLUSION: With current equipment, mechanical extraction provides a good combination of efficacy and safety.

Feasibility and efficacy of simultaneous pulmonary vein isolation and cavotricuspid isthmus ablation using cryotherapy.

INTRODUCTION: Pulmonary vein isolation (PVI) and cavotricuspid isthmus (CTI) ablation are often performed as part of the same procedure. In many cases, PVI is performed by cryotherapy and then CTI ablation by radiofrequency (RF) energy. We sought to determine whether it is more efficient to perform CTI ablation simultaneously with PVI using separate cryogenerators. METHODS AND RESULTS: We performed cryoablation of the CTI during PVI with the Arctic Front cryoballoon in 25 consecutive patients with clinical indications for both (PVI/CTI-cryo group). Procedural data were compared to those of 25 matched patients who underwent PVI only by the same operator (PVI-only group), and 25 patients who underwent PVI by cryotherapy and CTI ablation using RF energy sequentially during the same procedure (PVI/CTI-mixed group). No complication occurred. All veins were isolated; bidirectional CTI block was demonstrated in all cases where it was attempted, except for 1 patient in the PVI/CTI-mixed group. Procedure and fluoroscopy duration were significantly shorter in the PVI/CTI-cryo group (162 ± 34 and 24 ± 5 minutes) than in the PVI/CTI-mixed group (209 ± 46 minutes, P < 0.001 and 59 ± 28 minutes, P < 0.001). Procedure and fluoroscopy duration in the PVI-only group (155 ± 32 and 22 ± 8 minutes) were similar to those in the PVI/CTI-cryo group (P = NS) but significantly shorter than in the PVI/CTI-mixed group (P < 0.001 for both). Clinical outcomes were similar in all groups. CONCLUSION: When CTI ablation is performed with RF energy after PVI by cryoballoon, it adds significantly to the procedure and fluoroscopy durations; when performed contemporaneously using cryotherapy at both sites, the procedure and fluoroscopy durations are not prolonged.

P-wave abnormality predicts recurrence of atrial fibrillation after electrical cardioversion: a prospective study.

BACKGROUND: Maintenance of atrial fibrillation (AF) is related to atrial electrical inhomogeneity and resultant chaotic reentry. Our aim was to test the hypothesis that abnormalities of P morphology on the surface electrocardiogram (ECG) predict recurrent AF following electrical cardioversion (ECV). METHODS: A 12-lead ECG was recorded after ECV for persistent AF in 77 patients (51 men, 65 ± 10 years) and repeated 1 month later. P-wave duration was obtained in each lead using blinded on-screen measurement. Maximum P-wave duration (P-max) was defined as the longest measurable P-wave duration in any lead. P-wave dispersion (PWd) was calculated as the maximum-minimum P-wave duration. RESULTS: One month after ECV, 29 (38%) patients maintained sinus rhythm. Compared with the sinus rhythm group, those with recurrent AF had significantly greater PWd (66 ± 19 vs 57 ± 16 ms, P = 0.024) and included more patients with P-max ≥142 ms (65% vs 38%, P = 0.023). Using a cutoff of ≥62 ms for PWd and ≥142 ms for P-max, both indices had similar predictive value (sensitivity 66.7 and 64.6%, specificity 58.6 and 62.1%, respectively). In multiple regression analysis, including established clinical predictors, P-max ≥142 ms was the only independent predictor of AF recurrence (P = 0.025). CONCLUSION: A prolonged P-wave duration measured by 12-lead ECG predicts recurrent AF within 1 month after ECV.

Skin burns associated with radiofrequency catheter ablation of cardiac arrhythmias.

Skin burns are a rare complication associated with radiofrequency catheter ablation of cardiac arrhythmias. Burns related to the indifferent electrode patch may be severe and result in significant comorbidity. We describe our experience of skin burns and discuss potential predisposing and possible causative factors.

Is there a role for bi-atrial pacing resynchronisation therapy in the management of drug-refractory atrial fibrillation in patients unsuitable for left atrial ablation?

BACKGROUND: This retrospective cohort study evaluated whether long term outcome of atrial resynchronisation therapy using bi-atrial pacing (BiaP) to treat atrial fibrillation (AF) was effective in patients deemed unfit for left atrial (LA) ablation procedures. METHODS AND RESULTS: The patient population comprised 2 groups: those deemed suitable for left LA ablation (n=14) and those who were not (n = 17). Both groups underwent BiaP and outcomes were evaluated by comparing symptoms, AF duration, admissions and antiarrhythmic drugs (AAD) for an equal period of time pre and post implantation. Median follow-up was 24 months (range 8-66 months) for the unsuitable group and 31 months (range 7-84 months) for the suitable group. Efficacy in reduction of both AF and symptoms was similar (P = 0.44) in both groups (unsuitable group: 13/17; suitable group: 8/14). There was significant improvement in median AF episodes/week pre and post BiaP in both groups (unsuitable group AF reduction: 5 days/week, P = 0.001; suitable group AF reduction: 4.9 days/week, P = 0.03); the improvement was similar in both groups (P = 0.33). There was a significant reduction in the median number of admissions for AF in both groups (unsuitable group: P = 0.003; suitable group: P = 0.01) and this reduction was also similar (P = 0.70). The median number of AAD was also reduced to a similar degree (P = 0.83) in both groups (suitable group: P = 0.004; unsuitable group: P = 0.001). CONCLUSIONS: Atrial resynchronisation therapy is effective in the long term management of drug-resistant AF in patients unsuitable for LA ablation, leading to significant reductions in symptoms, AF duration, admissions and AAD.

The Ventricular Ectopic QRS Interval: A Potential Marker for Ventricular Arrhythmia in Ischemic Heart Disease.

OBJECTIVES: The purpose of this study was to determine the potential value of a novel marker for the severity of structural heart disease and the risk of arrhythmia. BACKGROUND: The ventricular ectopic QRS interval (VEQSI) has been shown to identify structural heart disease and predict mortality in an unselected population. In ischemic heart disease (IHD), risk stratification for sudden death is imperfect. We hypothesized that VEQSI would identify patients with prior myocardial infarction (MI) compared with healthy subjects and distinguish IHD patients who have suffered life-threatening events from those without prior significant ventricular arrhythmia. METHODS: The 12-lead Holter recordings from 189 patients with previous MI were analyzed: 38 with prior ventricular tachycardia/ventricular fibrillation (MI-VT/VF) (66 ± 9 years; 92% male); 151 without prior significant ventricular arrhythmia (MI-no VT/VF) (64 ± 11 years; 74% male). These were compared with 60 healthy controls (62 ± 7 years; 70% male). All ventricular ectopic beats were reviewed and maximal VEQSI duration (VESQI max) was recorded as the duration of the longest ventricular ectopic beat. RESULTS: VEQSI max was longer in post-MI patients compared with normal controls (185 ± 26 ms vs. 164 ± 16 ms; p < 0.001) and in MI-VT/VF patients with prior life-threatening events compared with MI-no VT/VF patients without prior life-threatening events (214 ± 20 ms vs. 177 ± 22 ms; p < 0.001). Multivariate analysis established VEQSI max as the strongest independent marker for prior serious ventricular arrhythmia. VEQSI max >198 ms had 86% sensitivity, 85% specificity, 62% positive predictive value, and 96% negative predictive value for identifying patients with prior life-threatening events (odds ratio: 37.4; 95% confidence interval: 13.0 to 107.5). CONCLUSIONS: VEQSI max >198 ms distinguishes post-MI patients with prior life-threatening events from those without prior significant ventricular arrhythmia. This may be a useful additional index for risk stratification in IHD.

Ventricular fibrillation treated by cryotherapy to the right ventricular outflow tract: a case report.

BACKGROUND: Arrhythmias originating from the right ventricular outflow tract are generally considered benign but cases of cardiac arrest have been described, usually associated with polymorphic ventricular tachycardia or extrasystoles with short coupling intervals. CASE PRESENTATION: We report the case of a 54-year-old Caucasian woman with symptomatic right ventricular outflow tract arrhythmias without structural heart disease who suffered a ventricular fibrillation arrest without prior malignant clinical features. Cryoablation was performed and an implantable cardioverter defibrillator was implanted. She has since been free of arrhythmia for 7 years and has asked that the implantable cardioverter defibrillator not be replaced when the battery becomes depleted. CONCLUSIONS: Although usually benign, right ventricular outflow tract tachycardia can be life-threatening. Even the most malignant cases can be cured by ablation.

Femoral implantation and pull through as an adjunct to traditional methods in cardiac resynchronization therapy.

BACKGROUND: We have described the use of femoral access followed by pull through of the lead to a pectoral position to circumvent difficulty in implanting a left ventricular (LV) lead by standard methods. OBJECTIVE: The purpose of this study was to establish the effect of femoral implantation and pull through on the overall rate of success in percutaneous implantation of LV leads. METHODS: We collected data prospectively in all attempts at LV lead implantation from the time that we envisioned the femoral pull-through approach. RESULTS: In the 6 years to September 30, 2014, our group attempted to implant a new LV lead in 736 patients, including 16 who previously had failed attempts by other groups. A standard superior approach was successful in 726 of 731 patients (99.3%) in whom it was attempted. In 5 patients (0.7%), we failed to deliver a lead from a superior approach; in 5 of 16 patients, with previous failed attemtps (31%), we judged that those attempts had been exhaustive. In all 10 cases, LV lead placement was achieved from a femoral approach, with the procedure time being 186 ± 65 minutes. In the first case attempted, the pull through failed; the lead was tunneled to the pectoral generator. In 1 case, the coronary sinus was found to be occluded at the ostium: a transseptal approach was used with the subsequent pull through. No complication occurred. At 22.3 ± 18.5 months after the implantation, all systems implanted by a femoral approach continued to function. CONCLUSION: Used as an adjunct to standard methods, the femoral access and pull through method allows percutaneous LV lead placement in virtually all cases.