Impact of intracardiac echocardiography usage on the safety of cryoballoon atrial fibrillation ablation: Subanalysis of the prospective FREEZE cluster cohort study.

INTRODUCTION: Cryoballoon ablation (CBA) aiming at pulmonary vein isolation (PVI) became a standardized atrial fibrillation (AF) ablation procedure. Life-threatening complications like cardiac tamponade exist. Intracardiac echocardiography (ICE) usage is associated with superior safety in radiofrequency ablation. It is unclear if ICE has an impact on safety of CBA. METHODS: The FREEZE Cohort (NCT01360008) subanalysis included patients undergoing "PVI only" CBA. Patients with intraprocedural transesophageal echocardiography were excluded. Group A comprises conventional, group B ICE-guided CBA. Periprocedural results were compared. RESULTS: From 2011 to 2016, a total of 4189 patients were enrolled, and 1906 (45.5%) were included in this subanalysis, split up in two groups (A: 1066 [55.9%], B: 840 [44.1%]). Group A was younger (60.6 ± 10.8 vs. 62.4 ± 10.5 years, p < .001), with smaller left atria (41 vs. 43 mm, p < .001), and less persistent AF (23.1 vs. 38.1%, p < .001). Procedure, left atrial, and fluoroscopy times were shorter in group A as compared to group B. Dose area product was significantly higher in group A (2911 vs. 2072 cGyxcm2 , p < .001). In-hospital major adverse cerebrovascular and cardiac event rates including two deaths in group A were not different between groups (0.5% vs. 0.1%, p = .18). The rate of total procedural (10.4% vs. 5.1%, p < .001) and major complications (3.2% vs. 1.3%, p < .001) was significantly higher in group A. Cardiac tamponade occurred significantly more frequently in group A (8 [0.8%] vs. 1 [0.1%], p = .046). Independent predictors for major complications were female sex (odds ratio [OR] 2.03, p = .03) and non-ICE usage (OR 2.38, p = .02). No differences were observed for persistent phrenic nerve palsy, nor for groin complications. CONCLUSION: CBA was significantly safer and required less radiation if ICE was used, although the procedures were more complex. The risk of groin complications was not increased with ICE usage. Non-ICE usage was the only modifiable independent predictor of major complications.

Impact of timing and combination of different BNT162b2 and ChAdOx1-S COVID-19 basic and booster vaccinations on humoral immunogenicity and reactogenicity in adults.

In this single-center observational study with 1,206 participants, we prospectively evaluated SARS-CoV-2-antibodies (anti-S RBD) and vaccine-related adverse drug reactions (ADR) after basic and booster immunization with BNT162b2- and ChAdOx1-S-vaccines in four vaccination protocols: Homologous BNT162b2-schedule with second vaccination at either three or six weeks, homologous ChAdOx1-S-vaccination or heterologous ChAdOx1-S/BNT162b2-schedule, each at 12 weeks. All participants received a BNT162b2 booster. Blood samples for anti-S RBD analysis were obtained multiple times over a period of four weeks to six months after basic vaccination, immediately before, and up to three months after booster vaccination. After basic vaccination, the homologous ChAdOx1-S-group showed the lowest anti-S RBD levels over six months, while the heterologous BNT162b2-ChAdOx1-S-group demonstrated the highest anti-S levels, but failed to reach level of significance compared with the homologous BNT162b2-groups. Antibody levels were higher after an extended vaccination interval with BNT162b2. A BNT162b2 booster increased anti-S-levels 11- to 91-fold in all groups, with the homologous ChAdOx1-S-cohort demonstrated the highest increase in antibody levels. No severe or serious ADR were observed. The findings suggest that a heterologous vaccination schedule or prolonged vaccination interval induces robust humoral immunogenicity with good tolerability. Extending the time to boost-immunization is key to both improving antibody induction and reducing ADR rate.

Catheter ablation of ventricular arrhythmias and in-hospital mortality: insights from the German-wide Helios hospital network of 5052 cases.

AIMS: Catheter ablation (CA) of ventricular arrhythmias is one of the most challenging electrophysiological interventions with an increasing use over the last years. Several benefits must be weighed against the risk of potentially life-threatening complications which necessitates a steady reevaluation of safety endpoints. Therefore, the aims of this study were (i) to investigate overall in-hospital mortality in patients undergoing such procedures and (ii) to identify variables associated with in-hospital mortality in a German-wide hospital network. METHODS AND RESULTS: Between January 2010 and September 2018, administrative data provided by 85 Helios hospitals were screened for patients with main or secondary discharge diagnosis of ventricular tachycardia (VT) or premature ventricular contractions (PVCs) in combination with an arrhythmia-related CA using ICD- and OPS codes. In 5052 cases (mean age 60.9 ± 14.3 years, 30.1% female) of 30 different hospitals, in-hospital mortality was 1.27% with a higher mortality in patients ablated for VT (1.99%, n = 2, 955) compared to PVC (0.24%, n = 2, 097, P < 0.01). Mortality rates were 2.06% in patients with ischaemic heart disease (IHD, n = 2, 137), 1.47% in patients with non-ischaemic structural heart disease (NIHD, n = 1, 224), and 0.12% in patients without structural heart disease (NSHD, n = 1, 691). Considering different types of hospital admission, mortality rates were 0.35% after elective (n = 2, 825), 1.60% after emergency admission/hospital transfer <24 h (n = 1, 314) and 3.72% following delayed hospital transfer >24 h after initial admission (n = 861, P < 0.01 vs. elective admission and emergency admission/hospital transfer <24 h). In multivariable analysis, a delayed hospital transfer >24 h [odds ratio (OR) 2.28, 95% confidence interval (CI) 1.59-3.28, P < 0.01], the occurrence of procedure-related major adverse events (OR 6.81, 95% CI 2.90-16.0, P < 0.01), Charlson Comorbidity Index (CCI, OR 2.39, 95% CI 1.56-3.66, P < 0.01) and its components congestive heart failure (OR 8.04, 95% CI 1.71-37.8, P < 0.01), and diabetes mellitus (OR 1.59, 95% CI 1.13-2.22, P < 0.01) were significantly associated with in-hospital death. CONCLUSIONS: We reported in-hospital mortality rates after CA of ventricular arrhythmias in the largest multicentre, administrative dataset in Germany which can be implemented in quality management programs. Aside from comorbidities, a delayed hospital transfer to a CA performing centre is associated with an increased in-hospital mortality. This deserves further studies to determine the optimal management strategy.

Sex differences of resource utilisation and outcomes in patients with atrial arrhythmias and heart failure.

OBJECTIVE: Atrial fibrillation or atrial flutter (AF) and heart failure (HF) often go hand in hand and, in combination, lead to an increased risk of death compared with patients with just one of both entities. Sex-specific differences in patients with AF and HF are under-reported. Therefore, the aim of this study was to investigate sex-specific catheter ablation (CA) use and acute in-hospital outcomes in patients with AF and concomitant HF in a retrospective cohort study. METHODS: Using International Statistical Classification of Diseases and Related Health Problems and Operations and Procedures codes, administrative data of 75 hospitals from 2010 to 2018 were analysed to identify cases with AF and HF. Sex differences were compared for baseline characteristics, right and left atrial CA use, procedure-related adverse outcomes and in-hospital mortality. RESULTS: Of 54 645 analysed cases with AF and HF, 46.2% were women. Women were significantly older (75.4±9.5 vs 68.7±11.1 years, p<0.001), had different comorbidities (more frequently: cerebrovascular disease (2.4% vs 1.8%, p<0.001), dementia (5.3% vs 2.2%, p<0.001), rheumatic disease (2.1% vs 0.8%, p<0.001), diabetes with chronic complications (9.7% vs 9.1%, p=0.033), hemiplegia or paraplegia (1.7% vs 1.2%, p<0.001) and chronic kidney disease (43.7% vs 33.5%, p<0.001); less frequently: myocardial infarction (5.4% vs 10.5%, p<0.001), peripheral vascular disease (6.9% vs 11.3%, p<0.001), mild liver disease (2.0% vs 2.3%, p=0.003) or any malignancy (1.0% vs 1.3%, p<0.001), underwent less often CA (12.0% vs 20.7%, p<0.001), had longer hospitalisations (6.6±5.8 vs 5.2±5.2 days, p<0.001) and higher in-hospital mortality (1.6% vs 0.9%, p<0.001). However, in the multivariable generalised linear mixed model for in-hospital mortality, sex did not remain an independent predictor (OR 0.96, 95% CI 0.82 to 1.12, p=0.579) when adjusted for age and comorbidities. Vascular access complications requiring interventions (4.8% vs 4.2%, p=0.001) and cardiac tamponade (0.3% vs 0.1%, p<0.001) occurred more frequently in women, whereas stroke (0.6% vs 0.5%, p=0.179) and death (0.3% vs 0.1%, p=0.101) showed no sex difference in patients undergoing CA. CONCLUSIONS: There are sex differences in patients with AF and HF with respect to demographics, resource utilisation and in-hospital outcomes. This needs to be considered when treating women with AF and HF, especially for a sufficient patient informed decision making in clinical practice.

[History of catheter ablation]. / Geschichte der Katheterablation.

After His bundle electrography was established in 1967, the step from invasive electrophysiologic diagnosis of arrhythmias to interventional treatment by catheter ablation was imminent. The time interval of 15 years between the diagnosis and treatment of arrhythmias was even shorter than the 19 years between the first selective coronary angiography in 1958 at the Cleveland Clinic in the USA and the first percutaneous coronary intervention in 1977 in Zurich. During each time period, a great amount of knowledge was gained in cardiac surgery, which proved to be very helpful for the development of the interventional treatment. The history of endovascular treatment is an impressive reminder that the preparation and support of cardiovascular surgeons and their handling of complications played a decisive role in the further development of cardiovascular internal medicine. The history of catheter ablation teaches us that the joint work of cardiologists and cardiovascular surgeons is of great importance for the choice and further development of the best possible treatment as for future development of the techniques of therapy.

Outcomes of cryoballoon or radiofrequency ablation in symptomatic paroxysmal or persistent atrial fibrillation.

AIMS: To evaluate the effectiveness and safety of cryoballoon ablation (CBA) compared with radiofrequency ablation (RFA) for symptomatic paroxysmal or drug-refractory persistent atrial fibrillation (AF). METHODS AND RESULTS: Prospective cluster cohort study in experienced CBA and RFA centres. Primary endpoint was 'atrial arrhythmia recurrence', secondary endpoints were as follows: procedural results, safety, and clinical course. A total of 4189 patients were included: CBA 2329 (55.6%) and RFA 1860 (44.4%). Cryoballoon ablation population was younger, with fewer comorbidities. Procedure time was longer in the RFA group (P = 0.01). Radiation exposure was 2487 (CBA) and 1792 cGycm2 (RFA) (P < 0.001). Follow-up duration was 441 (CBA) and 511 days (RFA) (P < 0.0001). Primary endpoint occurred in 30.7% (CBA) and 39.4% patients (RFA) [adjusted hazard ratio (adjHR) 0.85, 95% confidence interval (CI) 0.70-1.04; P = 0.12). In paroxysmal AF, CBA resulted in a lower risk of recurrence (adjHR 0.80, 95% CI 0.64-0.99; P = 0.047). In persistent AF, the primary outcome was not different between groups. Major adverse cardiovascular and cerebrovascular event rates were 1.0% (CBA) and 2.8% (RFA) (adjHR 0.53, 95% CI 0.26-1.10; P = 0.088). Re-ablations (adjHR 0.46, 95% CI 0.34-0.61; P < 0.0001) and adverse events during follow-up (adjHR 0.64, 95% CI 0.48-0.88; P = 0.005) were less common after CBA. Higher rehospitalization rates with RFA were caused by re-ablations. CONCLUSIONS: The primary endpoint did not differ between CBA and RFA. Cryoballoon ablation was completed rapidly; the radiation exposure was greater. Rehospitalization due to re-ablations and adverse events during follow-up were observed significantly less frequently after CBA than after RFA. Subgroup analysis suggested a lower risk of recurrence after CBA in paroxysmal AF. TRIAL REGISTRATION: ClinicalTrials.gov (NCT01360008), https://clinicaltrials.gov/ct2/show/NCT01360008.

In-hospital mortality of patients with atrial arrhythmias: insights from the German-wide Helios hospital network of 161 502 patients and 34 025 arrhythmia-related procedures.

Aims: Atrial fibrillation (AFib) and atrial flutter (AFlut) are common arrhythmias with increased use of invasive procedures. A steady re-evaluation of relevant safety endpoints is recommended and both quality management and pay-for-performance programs are evolving. Therefore, the aims of this study were (i) to investigate and report overall in-hospital mortality and mortality of invasive arrhythmia-related procedures and (ii) to identify mortality predictors in a German-wide hospital network. Methods and results: Administrative data provided by 78 Helios hospitals between 2010 and 2017 were examined using International Statistical Classification of Diseases and Related Health Problems- and Operations and Procedures-codes to identify patients with AFib or AFlut as main discharge diagnosis or secondary diagnosis combined with invasive arrhythmia-related interventions. In 161 502 patients, in-hospital mortality was 0.6% with a significant decrease from 0.75% to 0.5% (P < 0.01) during the observational period. In multivariable analysis, age [odds ratio (OR) 2.69, 95% confidence interval (CI) 2.36-3.05; P < 0.01], high centre volume (OR 0.57, 95% CI 0.50-0.65; P < 0.01), emergency hospital admission (OR 1.57, 95% CI 1.38-1.79; P < 0.01), and Charlson Comorbidity Index (CCI, OR 4.95, 95% CI 4.50-5.44; P < 0.01) were found as independent predictors of in-hospital mortality. Mortality rates were 0.05% for left atrial catheter ablation (CA, n = 21 744), 0.3% for right atrial CA (n = 9972), and 0.56% for implantation of a left atrial appendage occluder (n = 2309), respectively. Conclusion: We analysed for the first time in-hospital mortality rates of patients with atrial arrhythmias in a German-wide, multi-centre administrative dataset. This allows feasible, comparable, and up-to-date performance measurement of clinically important endpoints in a real-world setting which may contribute to quality management programs and towards value-based healthcare.

Cardiac tamponade in catheter ablation of atrial fibrillation: German-wide analysis of 21 141 procedures in the Helios atrial fibrillation ablation registry (SAFER).

Aims: Catheter ablation is an established therapy in patients with symptomatic atrial fibrillation (AF) with increasing popularity. Pericardial effusion requiring intervention (PE) is one of the most threatening adverse outcomes. The aim of this study was to examine rates of PE after catheter ablation in a large 'real-world' data set in a German-wide hospital network. Methods and results: Using ICD and OPS codes, administrative data of 85 Helios hospitals from 2010 to 2017 was used to identify AF catheter ablation cases [Helios atrial fibrillation ablation registry (SAFER)]. PE occurred in 0.9% of 21 141 catheter ablation procedures. Patients with PE were significantly older, to a higher percentage female, had more frequently hypertension, mild liver disease, diabetes with chronic complications, and renal disease. Low hospital volume (<50 procedures per year) and radiofrequency ablation (vs. cryoablation) were significantly associated with PE. Using two logistic regression models, age, female gender, hypertension, mild liver disease, diabetes with chronic complications, renal disease, low hospital volume, and radiofrequency ablation remained independent predictors for PE. Conclusion: Overall PE rate was 0.9%. Predictors for PE occurrence involved factors ascribed to the patient (age, gender, comorbidities), the type of catheter ablation (radiofrequency), and the institution (low-volume centres).

Sex-related outcome of atrial fibrillation ablation: Insights from the German Ablation Registry.

BACKGROUND: Stratification of patients with atrial fibrillation (AF) according to mechanistic and prognostic criteria may optimize the effectiveness and safety of catheter ablation. In women, AF is associated with more severe symptoms and worse prognosis. OBJECTIVE: We sought to assess sex-related differences in catheter ablation procedures and outcome in a large cohort of patients with AF. METHODS: A total of 3652 patients (1198 women [33%]; 2454 men [67%]) included in the German Ablation Registry were analyzed. Periprocedural parameters and outcome at 12-month follow-up were compared between male and female patients. RESULTS: Women were older at the time of ablation (women: 63.6 years; men: 59.1 years; P < .0001) and exhibited a higher prevalence of paroxysmal AF (women: 72%; men: 61%; P < .0001). They were less often affected by cardiovascular disease and reduced left ventricular function. Energy application duration and overall procedure duration were shorter in women. Conversely, the rate of major inhospital complications was increased in female patients (1.9% vs 0.8%; P = .023) and mainly driven by major bleeding events. At follow-up, women experienced higher AF recurrence rates (women: 50%; men: 45%; P = .017) and more often received oral medication for rhythm and rate control. In addition, the rate of pacemaker implantation was higher in the female cohort. Women more frequently reported femoral access site complications (women: 6%; men: 3%; P < .001). Overall, male patients were more often free from AF-related symptoms and satisfied with the treatment. CONCLUSION: Catheter ablation of AF was associated with a distinct sex-related outcome and complication profile that requires consideration in clinical practice.

German ablation registry: Cryoballoon vs. radiofrequency ablation in paroxysmal atrial fibrillation--One-year outcome data.

BACKGROUND: Although radiofrequency (RF) ablation has long been the standard of care for atrial fibrillation (AF) ablation, cryoballoon technology has emerged as a feasible approach with promising results. Prospective multicenter registry data referring to both ablation technologies in AF ablation are lacking so far. OBJECTIVE: The purpose of this study was to report data from the German ablation registry with respect to efficacy and safety in pulmonary vein ablation with different energy sources for paroxysmal AF after 1-year follow-up. METHODS: A total of 2306 patients with symptomatic paroxysmal AF from the German ablation registry were included in this analysis. The cohort was divided into two groups according to the ablation energy source used: cryoballoon and RF ablation. MACCE was defined as a combination of death, myocardial infarction, or stroke. RESULTS: AF recurrence rate after a single ablation procedure at 1 year follow-up was not significantly different between the two groups (45.8% after cryoablation and 45.4% after RF ablation, P = .87). Also, the rate of patients without AF recurrence and free of antiarrhythmic drug at 12-month follow-up was similar (cryoablation 44.2% and RF 41.4%, P = .25). MACCE occurred with an incidence of 0.7% within 500 days after cryoablation and 1.4% after RF ablation (P = .30). Persistent phrenic nerve palsy was more common after cryoablation compared to RF ablation (1.1% vs. 0.3%, P <.05). CONCLUSION: AF recurrence rate at 1-year follow-up was similar in RF ablation compared to cryoablation, whereas the spectrum and relevance of complications were significantly different between the two ablation methods. This finding might influence the choice of ablation method offered to the individual paroxysmal AF patient.

Shortening of freezing cycles provides equal outcome to standard ablation procedure using second-generation 28 mm cryoballoon after 15-month follow-up.

AIMS: Complications such as thermal oesophageal lesions, phrenic nerve injury, and pulmonary haemorrhage were found in cryoballoon (CB) ablation. Whether shortening of freezing times translates into equal efficacy rate and outcome is unknown. The aim of this study was to test the hypothesis that a single freeze cycle per pulmonary vein (PV) without dormant conduction during adenosine infusion is equally effective to standard CB procedure with a bonus freeze after documented PV isolation (PVI). METHODS AND RESULTS: In 53 patients with drug-refractory atrial fibrillation (AF) demonstrating PVI after a single 240 s freeze cycle without PV activity during adenosine no additional bonus freeze was applied (study group). In 139 patients, PVI was performed using a bonus freeze (240 s) after documented PVI (control group). Primary endpoint was recurrence of AF. Secondary endpoint was the assessment of quality of life (QoL-score from 1 to 6, being 1 the best and 6 the worst). Follow-up (FU) was performed at 3, 6, and 12 months. Freedom from symptomatic AF during a mean FU of 458 ± 107 days was achieved in 43 (81%) patients in the study group and in 110 (79%) control patients (P = ns). The QoL-score improved equally in both groups (4.8 ± 0.9 to 2.1 ± 0.7, P < 0.05 and 4.7 ± 0.6 to 2.2 ± 0.6, P < 0.05). Procedure duration (79 ± 14 vs. 98 ± 16 min, P < 0.01) was shorter in the study group. Complication rate was similar in both groups. CONCLUSION: Shortening of freezing times to 4 min per PV without residual dormant PV conduction after adenosine provocation is equally effective to the standard CB ablation protocol using a bonus freeze.

Ablation of atrioventricular nodal reentrant tachycardia in the elderly: results from the German Ablation Registry.

BACKGROUND: Catheter ablation (CA) is considered the treatment of choice for patients with atrioventricular nodal reentrant tachycardia (AVNRT). However, there is a tendency to avoid CA in the elderly because of a presumed increased risk of periprocedural atrioventricular (AV) nodal block. OBJECTIVE: The purpose of this prospective registry was to assess age-related differences in the efficacy and safety of CA within a large population with AVNRT. METHODS: A total of 3,234 consecutive patients from 48 German trial centers who underwent CA of AVNRT between March 2007 and May 2010 were enrolled in this study. The cohort was divided into three age groups: <50 years (group 1, n = 1,268 [39.2%]; median age = 40 [30.0-45.0] years, 74.1% women), 50-75 years old (group 2, n = 1,707 [52.8%]; 63.0 [58.0-69.0] years, 63.0% women), and > 75 years old (group 3, n = 259 [8.0%]; 79.0 [77.0-82.0] years, 50.6% women). RESULTS: CA was performed with radiofrequency current (RFC) in 97.7% and cryoablation technology in 2.3% of all cases. No differences were observed among the three groups with regard to primary CA success rate (98.7% vs. 98.8 % vs. 98.5%; P = .92) and overall procedure duration (75.0 minutes [50.0-105.0]; P = .93). Hemodynamically stable pericardial effusion occurred in five group 2 (0.3%) and two group 3 (0.8%) patients but in none of the group 1 (P <.05) patients. Complete AV block requiring permanent pacemaker implantation occurred in two patients in group 1 (0.2%) and six patients in group 2 (0.4%) but none in group 3 (P = 0.41). During a median follow-up period of 511.5 days (396.0-771.0), AVNRT recurrence occurred in 5.7% of all patients. Patients >75 years (group 3) had a significantly longer hospital stay (3.0 days [2.0-5.0]) compared with group 1 (2.0 days [1.0-2.0]) or group 2 (2.0 days [1.0-3.0]) patients (P <.0001). CONCLUSION: CA of AVNRT is highly effective and safe and does not pose an increased risk for complete AV block in patients over 75 years of age, despite a higher prevalence of structural heart disease. Antiarrhythmic drug therapy is often ineffective in this age group; thus, CA for AVNRT should be considered the preferred treatment even in elderly patients.

Emergency catheter ablation in critical patients.

Emergency catheter ablation is justified in critical patients with drug-refractory life-threatening arrhythmias. The procedure can be used for ablation of an accessory pathway in preexcitation syndrome with high risk of ventricular fibrillation and in patients with shock due to ischemic cardiomyopathy and incessant ventricular tachycardia. Emergency catheter ablation can also be justified in patients with an electrical storm of the implanted cardioverter-defibrillator or in patients with idiopathic ventricular fibrillation.

Rationale for and design of the CREATIVE-AF trial: randomized, double-blind, placebo-controlled, crossover study of the effect of irbesartan on oxidative stress and adhesion molecules in patients with persistent atrial fibrillation.

BACKGROUND AND OBJECTIVE: Atrial fibrillation (AF) is the most common cardiac arrhythmia. Recent studies suggest there is an angiotensin II-dependent increase in adhesion molecules and oxidative stress parameters during AF. These alterations appear to contribute to inflammatory and prothrombotic changes in the atrial endocardium ('endocardial remodelling'), suggesting that patients with increased levels of these factors might be at risk of thromboembolic events. The purpose of the CREATIVE-AF (Impact of Irbesartan on Oxidative Stress and C-Reactive Protein Levels in Patients with Persistent Atrial Fibrillation) trial is to prove the principle concept that blockade of angiotensin II type 1 receptors by irbesartan reduces levels of circulating adhesion molecules and oxidative stress parameters in patients with persistent AF by 25% compared with placebo. METHODS: This is a prospective, randomized, double-blind, placebo-controlled, crossover study in patients with persistent/permanent AF. A total of 60 patients are planned to be included in the study. Patients will receive placebo and irbesartan therapy for 9 weeks each. Levels of adhesion molecules (intercellular adhesion molecule-1, vascular cell adhesion molecule-1), inflammatory markers (high sensitivity C-reactive protein, monocyte chemoattractant protein-1, von Willebrand factor, tumour growth factor-beta1, tumour necrosis factor-alpha, interleukin-6) and oxidative stress parameters (8-iso-prostaglandin F2alpha) will be determined after each treatment phase and compared with baseline levels. CONCLUSION: Angiotensin II type 1 receptor antagonists may help reduce levels of circulating adhesion molecules and oxidative stress parameters in patients with persistent AF. This article summarizes the rationale and design of the CREATIVE-AF trial, which has been designed to test this hypothesis.

High incidence of appropriate and inappropriate ICD therapies in children and adolescents with implantable cardioverter defibrillator.

Appropriate and inappropriate therapies of implantable cardioverter defibrillators have a major impact on morbidity and quality of life in ICD recipients, but have not been systematically studied in children and young adults during long-term follow-up. ICD implantation was performed in 20 patients at the mean age of 16 +/- 6 years, 11 of which had prior surgical repair of a congenital heart defect, 9 patients had other cardiac diseases. Implant indications were aborted sudden cardiac death in six patients, recurrent ventricular tachycardia in 9 patient, and syncope in 5 patients. Epicardial implantation was performed in 6 and transvenous implantation in 14 patients. Incidence, reasons and predictors (age, gender, repaired congenital heart disease, history of supraventricular tachycardia, and epicardial electrode system) of appropriate and inappropriate ICD therapies were analyzed during a mean follow-up period of 51 +/- 31 months range 18-132 months. There were a total 239 ICD therapies in 17 patients (85%) with a therapy rate of 2.8 per patient-years of follow-up. 127 (53%) ICD therapies in 15 (75%) patients were catagorized as appropriate and 112 (47%) therapies in 10 (50%) patients as inappropriate, with a rate of 1.5 appropriate and 1.3 inappropriate ICD therapies per patient-years of follow-up. Time to first appropriate therapy was 16 +/- 18 months. Appropriate therapies were caused by ventricular fibrillation in 29 and ventricular tachycardia in 98 episodes. Termination was successful by antitachycardia pacing in 4 (3%) and by shock therapy in 123 episodes (97%). Time to first inappropriate therapy was 16 +/- 17 months. Inappropriate therapies were caused by supraventricular tachycardia in 77 (69%), T wave oversensing in 19 (17%), and electrode defect in 16 episodes (14%). It caused shocks in 87 (78%) and only antitachycardia pacing in 25 episodes (22%). No clinical variable could be identified as predictor of either appropriate or inappropriate ICD therapies. There is a high rate of ICD therapies in young ICD recipients, the majority of which occur during early follow-up. The rate of inappropriate therapies is as high as 47% and is caused by supraventricular tachycardia and electrode complications in the majority of cases. Prospective trials are required to establish preventative strategies of ICD therapies in this young patient population.

Origin of electrical activation within the right atrial and left ventricular walls: differentiation by electrogram characteristics using the noncontact mapping system.

Clinical data using the noncontact mapping system (Ensite 3000) suggest that characteristics of the reconstructed unipolar electrograms may predict the origin of electrical activation within the atrial and ventricular walls (endocardial vs myocardial vs epicardial origin). Experimental data are lacking. In ten open-chest pigs (mean body weight 62 kg) cardiac pacing was performed at a cycle length of 600 ms with a pulse width of 2 ms and twice diastolic threshold from the endo-, the myo-, and the epicardium, respectively. Pacing was undertaken at three right atrial and three left ventricular sites, and cardiac activation was recorded with the Ensite system. Reconstructed unipolar electrograms at the location of earliest endocardial activation assessed by color coded isopotential maps were analyzed systematically for differences in morphology. The positive predictive value of atrial electrograms exhibiting an initial R wave during pacing for a subendocardial origin (i.e., myocardial or epicardial) was 0.96. The negative predictive value was 0.48. Electrograms generated during myocardial pacing exhibited increased maximal negative voltage and maximal dV/dt (-3 +/- 1.8 mV, -798 +/- 860 mV/ms, respectively) than the electrograms obtained during endocardial (-2 +/- 1 mV, -377 +/- 251 mV/ms, respectively) and epicardial pacing (-2.1 +/- 0.7 mV, -440 +/- 401 mV/ms, respectively, P<0.01 for both parameters). During pacing at the left ventricular wall, occurrence of an initial R wave did not differ significantly between electrograms reconstructed during endocardial and subendocardial pacing. All other characteristics of the unipolar ventricular electrograms analyzed, except latency, did not differ significantly when compared to stimulation depth. Morphological characteristics of unipolar electrograms generated by the noncontact mapping system during pacing of the atrium allowed for discrimination of an endocardial versus a subendocardial origin of activation. At the ventricular level, characteristics of unipolar electrograms did not predict the origin of cardiac activation in this experimental setting.

Intraatrial reentrant tachycardias in patients after atrial switch procedures for d-transposition of the great arteries Endocardial mapping and radiofrequency catheter ablation primarily targeting protected areas of atrial tissue within the systemic venous atrium.

Thirteen patients with d-transposition of the great arteries after the Mustard/Senning procedure underwent electrophysiological study for recurrent intraatrial reentrant tachycardia (IARTs). In 8 patients, a 20-pole electrode catheter and a steerable 7F mapping and ablation catheter were placed in the systemic venous atrium, and via the retrograde route in the pulmonary venous atrium, if required. During IART pace mapping and entrainment mapping were performed in order to localize protected areas of atrial tissue between anatomical and/or surgical barriers of electrical isolation. The systemic venous atrium of 5 patients was studied using the non-contact mapping system (Ensite 3000(TM)). Linear radiofrequency current lesions were induced after mapping of electrical protected areas from the medial aspect of the superior caval vein to the systemic venous atrium and/or intraatrial baffle or the intraatrial suture line in 4 patients, from the medial aspect of mitral valve annulus to the inferior caval vein in 5 patients, from the intraatrial suture line to the posterior systemic venous atrium in 1 patient and in 2 patients from the posterior and inferior pulmonary venous atrium to the tricuspid valve annulus. Subsequently, 14 of the 15 identified IARTs were not inducible during repeated programmed stimulation. Mean duration of the electrophysiological study was 202 min, mean fluoroscopy time was 21.6 min. During follow-up (mean 20 months), 10 of 12 patients with successful procedures are free of tachycardia, 2 patients developed IARTs with a new morphology. In the majority of our patients, curative treatment was feasible by induction of linear radiofrequency current lesions by primarily targeting electrical protected areas of atrial tissue in the systemic venous atrium.

European clinical experience with a dual chamber single pass sensing and pacing defibrillation lead.

Dual chamber ICDs are increasingly implanted nowadays, mainly to improve discrimination between supraventricular and ventricular arrhythmias but also to maintain AV synchrony in patients with bradycardia. The aim of this study was to investigate a new single pass right ventricular defibrillation lead capable of true bipolar sensing and pacing in the right atrium and integrated bipolar sensing and pacing in the right ventricle. The performance of the lead was evaluated in 57 patients (age 61 +/- 12 years; New York Heart Association 1.9 +/- 0.6, left ventricular ejection fraction 0.38 +/- 0.15) at implant, at prehospital discharge, and during a 1-year follow-up. Sensing and pacing behavior of the lead was evaluated in six different body positions. In four patients, no stable position of the atrial electrode could intraoperatively be found. The intraoperative atrial sensing was 2.3 +/- 1.6 mV and the atrial pacing threshold 0.8 +/- 0.5 V at 0.5 ms. At follow-up, the atrial sensing ranged from 1.5 mV to 2.2 mV and the atrial pacing threshold product from 0.8 to 1.7 V/ms. In 11 patients, an intermittent atrial sensing problem and in 24 patients an atrial pacing dysfunction were observed in at least one body position. In 565 episodes, a sensitivity of 100% and a specificity of 96.5% were found for ventricular arrhythmias. In conclusion, this single pass defibrillation lead performed well as a VDD lead and for dual chamber arrhythmia discrimination. However, loss of atrial capture in 45% of patients preclude its use in patients depending on atrial pacing.