Impact of preventive substrate catheter ablation on implantable cardioverter-defibrillator interventions in patients with ischaemic cardiomyopathy and infarct-related coronary chronic total occlusion.

AIMS: Primary prevention patients with ischaemic cardiomyopathy and chronic total occlusion of an infarct-related coronary artery (CTO) are at a particularly high risk of implantable cardioverter-defibrillator (ICD) therapy occurrence. The trial was designed to evaluate the efficacy of preventive CTO-related substrate ablation strategy in ischaemic cardiomyopathy patients undergoing primary prevention ICD implantation. METHODS AND RESULTS: The PREVENTIVE VT study was a prospective, multicentre, randomized trial including ischaemic patients with ejection fraction ≤40%, no documented ventricular arrhythmias (VAs), and evidence of scar related to the coronary CTO. Patients were randomly assigned 1:1 to a preventive substrate ablation before ICD implantation or standard therapy with ICD implantation only. The primary outcome was a composite of appropriate ICD therapy or unplanned hospitalization for VAs. Secondary outcomes included the primary outcome's components, the incidence of appropriate ICD therapies, cardiac hospitalization, electrical storm, and cardiovascular (CV) mortality. Sixty patients were included in the study. During the mean follow-up of 44.7 ± 20.7 months, the primary outcome occurred in 5 (16.7%) patients undergoing preventive substrate ablation and in 13 (43.3%) patients receiving only ICD [hazard ratio (HR): 0.33; 95% confidence interval (CI): 0.12-0.94; P = 0.037]. Patients in the preventive ablation group also had fewer appropriate ICD therapies (P = 0.039) and the electrical storms (Log-rank: P = 0.01). While preventive ablation also reduced cardiac hospitalizations (P = 0.006), it had no significant impact on CV mortality (P = 0.151). CONCLUSION: Preventive ablation of the coronary CTO-related substrate in patients undergoing primary ICD implantation is associated with the reduced risk of appropriate ICD therapy or unplanned hospitalization due to VAs.

Assessment of Esophageal Shifts during Catheter Ablation of Atrial Fibrillation Using Intracardiac Ultrasound Integrated with 3-Dimensional Electroanatomical Mapping System.

Purpose: Atrioesophageal fistula is one of the most feared complications of radiofrequency catheter ablation (RFCA) of atrial fibrillation (AF) as it is associated with high mortality. Determining the esophagus location during RFCA might reduce the risk of esophageal injury. The present study aims to evaluate the feasibility of using intracardiac echocardiography integrated into a 3-dimensional electroanatomical mapping system (ICE/3D EAM) for the assessment of esophageal position and shifts in response to ablation. Methods: We prospectively enrolled 20 patients that underwent RFCA of AF under conscious analgosedation. The virtual anatomy of the left atrium, the pulmonary vein (PV) ostia, and the esophagus was created with ICE/3D EAM. The esophageal positions were obtained at the beginning of the procedure and then after left and right PV isolation (PVI). Esophageal shifts were measured offline after the procedure using the tools available in the 3D EAM system. Results: Most esophagi moved away from the ablated PV ostia. After the left PVI, the median of the shifts was 2.8 mm (IQR 1.0-6.3). In 25% of patients, the esophagus shifted by >5.0 mm (max. 13.4 mm). After right PVI, the median of shifts was 2.0 mm (IQR 0.7-4.9). In 10% of patients, the esophageal shift was >5.0 mm (max. 7.8 mm). Conclusions: ICE/3D EAM enables the intraprocedural visualization of baseline esophageal position and its shifts after PVI. The shifts are variable, but they tend to be small and directed away from the ablation site. Repeated intraprocedural visualization of the esophagus may be needed to reduce the risk of esophageal injury.

How Imaging Techniques Improve Ventricular Arrhythmia Ablation: A Multimodality-Based Approach.

Although implantable cardioverter defibrillators offer the best protection against sudden cardiac death, catheter ablation for ventricular arrhythmias (VAs) can modify or prevent this event from occurring. In order to achieve a successful ablation, the correct identification of the underlying arrhythmogenic substrate is mandatory to tailor the pre-procedural planning of an ablative procedure as appropriately as possible. We propose that several of the imaging modalities currently used could be merged, including echocardiography (also intracardiac), cardiac magnetic resonance, cardiac computed tomography, nuclear techniques, and electroanatomic mapping. The aim of this state-of-the-art review is to present the value of each modality, that is, its benefits and limitations, in the assessment of arrhythmogenic substrate. Moreover, VAs can be also idiopathic, and in this paper we will underline the role of these techniques in facilitating the ablative procedure. Finally, a hands-on workflow for approaching such a VA and future perspectives will be presented.

Intermittent ventricular pre-excitation in symptomatic adults: Always a marker of low risk?

BACKGROUND: Intermittent ventricular pre-excitation was considered a low-risk marker for sudden death. However, to date, some studies do not exclude the existence of accessory pathways (APs) with high-risk intermittent antegrade conductive properties. According to current European Guidelines, high-risk features of APs are antegrade pathway conduction ≤250 ms in baseline or during the adrenergic stimulus, inducibility of atrioventricular reciprocating tachycardias (AVRT), inducibility of pre-excited atrial fibrillation (AF), and presence of multiple APs. For all of these transcatheter ablation is recommended. The aim of our study was to evaluate the existence of differences in risk characteristics between patients with intermittent pre-excitation (IPX) and those with persistent pre-excitation (PPX), from a sample of adults with ventricular pre-excitation and symptoms like palpitations. METHODS: 293 adults [IPX: 51 (17.4%); PPX: 242 (82.6%)] underwent electrophysiological study and then catheter ablation of their APs if arrhythmia inducibility (AVRT/AF) was noted, or, conversely, if it was appreciated a fast AP antegrade conduction, in baseline or during intravenous isoproterenol infusion, or if multiple APs were detected. RESULTS: There were no statistically significant differences in demographic characteristics (age and gender), AVRT/AF inducibility, antegrade conductive properties, the prevalence of multiple APs, and APs locations between IPX and PPX patients. CONCLUSIONS: In our study, patients with IPX did not show significant differences in clinical and electrophysiological features versus PPX patients.

Ablation of residual potentials along the circumferential line reduces acute pulmonary vein reconnection.

INTRODUCTION: Acute pulmonary vein (PV) reconnection is frequently encountered in patients undergoing PV isolation (PVI) procedure for the treatment of atrial fibrillation. In this study, we investigated whether the identification and ablation of residual potentials (RPs), after the initial achievement of PVI, reduces acute PV reconnection rate. METHODS: Following PVI in 160 patients, mapping along the ablation line was performed to identify RPs, defined as bipolar amplitude ≥0.2 mV or 0.1-0.19 mV combined with a negative component of the unipolar electrogram. Ipsilateral PV sets with RPs were randomized to either no further ablation (Group B) or to additional ablation of the identified RPs (Group C). The primary study endpoint was spontaneous or adenosine-mediated acute PV reconnection after a 30-min waiting period and was also evaluated in ipsilateral PV sets without RPs (Group A). RESULTS: After isolation of 287 PV pairs, 135 had no RPs (Group A), whereas the remaining PV pairs were randomized to either Group B (n = 75) or Group C (n = 77). Ablation of RPs resulted in a reduction of spontaneous or adenosine-mediated PV reconnection rate (16.9% in Group C vs 48.0% in Group B; p < 0.001). Group A was associated with a significantly lower percentage of acute PV reconnection as compared to Group B (5.9% vs 48.0%; p < 0.001) and Group C (5.9% vs 16.9%; p = 0.016). CONCLUSION: After PVI achievement, the absence of RPs along the circumferential line is associated with a low likelihood of acute PV reconnection rate. Ablation of RPs significantly reduces spontaneous or adenosine-mediated acute PV reconnection rate.

Conventional fluoroscopy-guided versus zero-fluoroscopy catheter ablation of supraventricular tachycardias.

PURPOSE: The aim of this study was to evaluate the safety and efficacy of zero-fluoroscopy (ZF) catheter ablation (CA) for supraventricular tachycardias (SVT). METHODS: 584 consecutive patients referred to our institution for CA of SVT were analysed. Patients were categorised into two groups; zero-fluoroscopy (ZF) group and conventional fluoroscopy (CF) group. The ZF group was further divided into two subgroups (adults and paediatric). Patient characteristics, procedural information, and follow-up data were compared. RESULTS: The ZF group had a higher proportion of paediatric patients (42.2% vs 0.0%; p < 0.001), resulting in a younger age (30.9 ± 20.3 years vs 52.7 ± 16.5 years; p < 0.001) and lower BMI (22.8 ± 5.7 kg/m2 vs 27.0 ± 5.4 kg/m2; p < 0.001). Procedure time was shorter in the ZF group (94.2 ± 50.4 min vs 104.0 ± 54.0 min; p = 0.002). There were no major complications and the rate of minor complications did not differ between groups (0.0% vs 0.4%; p = 0.304). Acute procedural success as well as the long-term success rate when only the index procedure was considered did not differ between groups (92.5% vs 95.4%; p = 0.155; 87.1% vs 89.2%; p = 0.422). When repeated procedures were included, the long-term success rate was higher in the ZF group (98.3% vs 93.5%; p = 0.004). The difference can be partially explained by the operators' preferences. CONCLUSION: The safety and efficacy of ZF procedures in adult and paediatric populations are comparable to that of CF procedures.

Biventricular versus His bundle pacing after atrioventricular node ablation in heart failure patients with narrow QRS.

Background: His bundle pacing (HBP) is a physiological alternative to biventricular (BiV) pacing. We compared short-term results of both pacing approaches in symptomatic atrial fibrillation (AF) patients with moderately reduced left ventricular (LV) ejection fraction (EF ≥35% and <50%) and narrow QRS (≤120 ms) who underwent atrioventricular node ablation (AVNA).Methods: Thirty consecutive AF patients who received BiV pacing or HBP in conjunction with AVNA between May 2015 and January 2020 were retrospectively assessed. Electrocardiographic, echocardiographic, and clinical data at baseline and 6 months after the procedure were assessed.Results: Twenty-four patients (age 68.8 ± 6.5 years, 50% female, EF 39.6 ± 4%, QRS 95 ± 10 ms) met the inclusion criteria, 12 received BiV pacing and 12 HBP. Both groups had similar acute procedure-related success and complication rates. HBP was superior to BiV pacing in terms of post-implant QRS duration, implantation fluoroscopy times, reduction of indexed LV volumes (EDVi 63.8 (49.6-81) mL/m2 vs. 79.9 (66-100) mL/m2, p = 0.055; ESVi 32.7 (25.6-42.6) mL/m2 vs. 46.4 (42.9-68.1) mL/m2, p = 0.009) and increase in LVEF (46 (41-55) % vs. 38 (35-42) %, p = 0.005). However, the improvement of the NYHA class was similar in both groups.Conclusions: In symptomatic AF patients with moderately reduced EF and narrow QRS undergoing AVNA, HBP could be a conceivable alternative to BiV pacing. Further prospective studies are warranted to address the outcomes between both 'ablate and pace' strategies.

Differences in activated clotting time and total unfractionated heparin dose during pulmonary vein isolation in patients on different anticoagulation therapy.

BACKGROUND: Periprocedural pulmonary vein isolation (PVI) anticoagulation requires balancing between bleeding and thromboembolic risk. Intraprocedural anticoagulation is monitored by activated clotting time (ACT) with target value >300 s, and there are no guidelines specifying an initial unfractionated heparin (UFH) dose. METHODS: We aimed to assess differences in ACT values and UFH dosage during PVI in patients on different oral anticoagulants. We conducted an international, multi-center, registry-based study. Consecutive patients with atrial fibrillation (AF) undergoing PVI, on uninterrupted anticoagulation therapy, were analyzed. Before transseptal puncture, UFH bolus of 100 IU/kg was administered regardless of the anticoagulation drug. RESULTS: Total of 873 patients were included (median age 61 years, IQR 53-66; female 30%). There were 248, 248, 189, 188 patients on warfarin, dabigatran, rivaroxaban, and apixaban, respectively. Mean initial ACT was 257 ± 50 s, mean overall ACT 295 ± 45 s and total UFH dose 158 ± 60 IU/kg. Patients who were receiving warfarin and dabigatran compared to patients receiving rivaroxaban and apixaban had: (i) significantly higher initial ACT values (262 ± 57 and 270 ± 48 vs. 248 ± 42 and 241 ± 44 s, p < .001), (ii) significantly higher ACT throughout PVI (309 ± 46 and 306 ± 44 vs. 282 ± 37 and 272 ± 42 s, p < .001), and (iii) needed lower UFH dose during PVI (140 ± 39 and 157 ± 71 vs. 171 ± 52 and 172 ± 70 IU/kg). CONCLUSION: There are significant differences in ACT values and UFH dose during PVI in patients receiving different anticoagulants. Patients on warfarin and dabigatran had higher initial and overall ACT values and needed lower UFH dose to achieve adequate anticoagulation during PVI than patients on rivaroxaban and apixaban.

Fluoroless radiofrequency and cryo-ablation of atrioventricular nodal reentry tachycardia in adults and children: a single-center experience.

BACKGROUND: Radiofrequency ablation (RFA) and cryo-ablation (CRA) have been traditionally performed with fluoroscopy which exposes patients and medical staff to the potential harmful effects of the X-ray. Therefore, we aimed to assess the feasibility, safety, and effectiveness of RFA and CRA of atrioventricular nodal reentry tachycardia (AVNRT) guided by the three-dimensional (3D) electro-anatomical mapping (EAM) system without the use of fluoroscopy. METHODS: We analyzed 168 consecutive patients with AVNRT, 62 of whom were under 19 years of age (128 in RFA (age 34.04 ± 21.0 years) and 40 in CRA (age 39.41 ± 22.8 years)). All procedures were performed completely without the use of the fluoroscopy and with the 3D EAM system. RESULTS: The acute success rates (ASR) of the two ablation methods were very high and similar (for RFA 126/128 (98.4%) and for CRA 40/40 (100%); p = 0.43). Total procedural time (TPT) was similar in RFA and CRA groups (75.04 ± 42.31 min and 73.12 ± 30.54 min, respectively; p = 0.79). Recurrence rates (1 (2.5%) and 8 (6.25%); p = 0.35) were similar. There were no complications associated with procedures in either group. In pediatric group, ASR (61/62 (98.38%) and 105/106 (99.05%), respectively; p = 0.69) and TPT (75.16 ± 42.2 min and 74.23 ± 38.3 min, respectively; p = 0.88) were similar to the adult group. High ASR was observed with both ablation methods (for RFA 49/50, 98%, and for CRA 12/12, 100%; p = 0.62] with very high arrhythmia-free survival rates (for RFA 98% and for CRA 100%; p = 0.62). CONCLUSION: Based on these results, it can be suggested that fluoroless RFA or CRA guided by the 3D EAM system can be routinely performed in all patients with AVNRT without compromising safety, efficacy, or duration of the procedure.

Treatment of left-sided extension of AV node: A valuable integration of advance imaging modalities and cryoablation.

We present a case of successful cryoablation of the left extension of the atrioventricular (AV) node for treatment of a recurrent atrioventricular nodal reentry tachycardia without the use of fluoroscopy. Three-dimensional electroanatomic mapping system and intracardiac echocardiography were used to navigate catheters in the heart and position them according to anatomical landmarks. Due to the nature of cryoablation lesion formation, lesions were able to be applied safely in right atrium, as well as in left atrium, without damaging AV node or bundle of His.

Intra-cardiac ultrasound guided approach for catheter ablation of typical right free wall accessory pathways.

BACKGROUND: Right free wall accessory pathways (AP) are difficult to treat with catheter ablation as ablation catheter (AC) instability at the tricuspid annulus often precludes successful procedure. The aim of our study was to test a novel intra-cardiac echocardiography (ICE) guided technique for AC placement. Feasibility and success rates were observed. METHODS: Eight consecutive patients (aged 29 ± 21 years, 4 female) with Wolff-Parkinson-White syndrome and a right free wall AP were included in the study. ICE, three-dimensional (3D) electro-anatomic mapping (EAM) system, and a steerable long sheath were used together with either an irrigated or a non-irrigated tip radio-frequency AC to achieve a "loop" manoeuvre which provided AC tip stability at the ventricular aspect of the tricuspid annulus. X-ray fluoroscopy was not used. RESULTS: Three patients had an anterior and five had a lateral location of the right free wall AP. Procedures were successful in all patients, without recurrences during the mean follow-up of 397 ± 363 days. Average procedural duration was 90 ± 31 min. On average, 6.6 ± 5.7 ablations were needed. Average time to terminate AP conduction after the start of ablation was 4.8 ± 4.2 s. In five patients (62%) AP conduction was successfully terminated with the first ablation. There were no procedural complications. CONCLUSIONS: The novel ICE-guided approach with concomitant use of the steerable sheath and the 3D EAM system for zero-fluoroscopy mapping and ablation of the right free wall APs proved feasible and resulted in excellent acute and long-term outcomes.

Combined use of electro-anatomic mapping system and intracardiac echocardiography to achieve zero-fluoroscopy catheter ablation for treatment of paroxysmal atrial fibrillation: a single centre experience.

Fluoroscopy is the principal imaging method for catheter ablation (CA) of atrial fibrillation (AF). However, radiation exposure carries potential health risk to patients and operators alike. Our aim was to study safety and efficacy of zero-fluoroscopy CA of paroxysmal AF with a combined use of electroanatomic mapping system (EAM) and intracardiac echocardiography (ICE). In addition, impact of ICE/EAM automatic integration system and contact force (CF) sensing technology on procedural times were assessed. We included 144 consecutive patients (69% males, age 60 ± 10 years, BMI 29 ± 4,6) referred for CA of symptomatic paroxysmal AF. All procedures were performed only with EAM system and ICE. No fluoroscopy was used. The acute procedural success of complete pulmonary vein isolation was achieved in all patients (100%) and adverse events were detected in eight patients (5.6%). In 53 (37%) patients the use of ICE/EAM automatic integration system shortened procedural times compared to those performed without it (148 ± 35 vs. 187 ± 44 min, p < 0.05). Similarly, 89 (60%) procedures where CF sensing catheter was used were shorter compared to those performed without it (163 ± 41 vs. 188 ± 46 min, p < 0.05). Zero-fluoroscopy approach for treatment of paroxysmal AF seems feasible, safe, and acutely effective. Additional reduction of procedural times could be achieved with the use of ICE/EAM automatic integration system and CF sensing technology.

Radiofrequency catheter ablation versus balloon cryoablation of atrial fibrillation: markers of myocardial damage, inflammation, and thrombogenesis.

BACKGROUND: Evidence from animal and human studies suggests that cryoablation might be associated with a lesser inflammatory response and activation of coagulation compared with radiofrequency ablation. The study was aimed at comparing the effect of cryoballoon and radiofrequency catheter ablation of paroxysmal atrial fibrillation on markers of myocardial damage, inflammation, and activation of coagulation. METHODS: Forty-one patients received either cryoballoon (n = 23) or radiofrequency (n = 18) ablation of atrial fibrillation. We measured troponin I, high-sensitivity CRP, and interleukin 6 at baseline from the cubital vein, and from the right and left atrium before and after ablation, and from the cubital vein the following day. Prothrombin fragments 1 + 2, soluble P­selectin, and D­dimer were measured before and after ablation from both atria. RESULTS: We observed higher troponin I release in the cryoballoon than in the radiofrequency group (7.01 mcg/l (interquartile range [IQR]: 5.30-9.09) vs 2.32 mcg/l (IQR: 1.45-2.98), p < 0.001). The levels of inflammatory markers (high-sensitivity CRP and interleukin 6) in the two groups were comparable, as were the levels of markers of coagulation activation. Procedure duration, fluoroscopy times, and mid-term success (23 months, IQR 7-32) of the two groups were also comparable. CONCLUSIONS: Cryoballoon ablation of atrial fibrillation causes more significant myocardial damage, that is, more extensive ablation lesions, compared with radiofrequency catheter ablation. However, no major differences between these two ablation techniques with regard to the inflammatory response and activation of the coagulation system were observed.

Improvement of Atrial and Ventricular Remodeling with Low Atrial Fibrillation Burden after Hybrid Ablation of Persistent Atrial Fibrillation.

BACKGROUND: An endoscopic transdiaphragmatic epicardial radiofrequency ablation procedure combined with percutaneous endocardial radiofrequency ablation--a hybrid procedure--is a potentially curative treatment option for patients with persistent atrial fibrillation (AF). Long-term effects of arrhythmia elimination on atrial and ventricular remodeling are not completely understood. Therefore, the aim of our study was to quantify echocardiographic structural and functional changes of the left atrium (LA) and left ventricle (LV) following a hybrid procedure. METHODS AND RESULTS: Thirty-seven consecutive patients with symptomatic drug refractory persistent AF underwent a hybrid procedure to achieve complete pulmonary vein and LA posterior wall electrical isolation. AF burden was measured using an insertable electrocardiographic (ECG) monitor. Patients were divided into responders to ablation and nonresponders according to postoperative AF burden at 12-month follow-up (responder < 0.5% vs nonresponder ≥ 0.5%). Median AF burden was 0.32 (0.04-27.5)% for all patients. In responders (19/37 patients), significant echocardiographic reduction of LA volume index from 47 to 41 mL/m(2) (P < 0.05) and improvement of LA function parameters (LA stiffness from 73.3 to 41.3 [P < 0.05], LA emptying fraction from 21% to 45% [P < 0.05], LA global longitudinal strain from 11.2% to 18.8% [P < 0.5]) was documented. In addition, LV systolic function significantly improved in comparison with nonresponders. CONCLUSION: Hybrid ablation of persistent AF achieved stable sinus rhythm in a significant proportion of patients, as evidenced by continuous ECG monitoring, resulting in important LA and LV reverse remodeling after 12 months.

Hemoglobin A1c is a better predictor of prognosis following the non-ST elevation acute coronary syndrome than fasting and admission glucose.

BACKGROUND: Glucometabolic status is an important predictor of prognosis in patients with acute myocardial infarction. Both plasma glucose levels and glycosylated hemoglobin A1c (HbA1c) were implicated as predictors of prognosis. However, previous data yielded conflicting results. We evaluated the prognostic role of plasma glucose levels and HbA1c in patients with non-ST elevation acute coronary syndrome (NSTEACS). METHODS: A total of 106 consecutive patients with NSTEACS (55 with unstable angina and 51 with non-ST elevation myocardial infarction) were included. The average age was 66.1 years; 61% were male. HbA1c was measured at admission, along with other standard laboratory values. The follow-up period lasted for a year. The main combined outcome variable included death from cardiovascular causes and rehospitalization due to another acute coronary syndrome or due to heart failure. RESULTS: Combined end point occurred in 43 (41%) patients. Mean HbA1c value was significantly higher in the group of patients who had complications (7.6 ± 2.6 vs. 5.8 ± 1.2, p < 0.05). Logistic regression identified HbA1c [odds ratio (OR): 1.6] and male sex (OR: 0.25) as the only independent predictors of major adverse cardiac events (MACE). A Kaplan-Meier analysis showed a 2.7 times higher risk of MACE in patients with HbA1c > 6.5%. CONCLUSIONS: Results from our study indicate that the admission level of HbA1c, but not admission or fasting glucose, is a predictor of mortality and major adverse events in patients with NSTEACS. These results identify HbA1c to be an independent predictor also in patients with NSTEACS, and not only in those with ST elevation myocardial infarction as observed before our study.

Low rate of atrial fibrillation recurrence verified by implantable loop recorder monitoring following a convergent epicardial and endocardial ablation of atrial fibrillation.

OBJECTIVE: Evaluate long-term outcomes in patients undergoing the Convergent procedure (CP) for the treatment of atrial fibrillation (AF). BACKGROUND: The CP provides a multidisciplinary approach, combining endoscopic creation of epicardial linear lesions followed by endocardial mapping and ablation and targets persistent and longstanding persistent AF patients who are at increased risk of heart failure, stroke, and mortality. METHODS: Outcomes from a prospective nonrandomized study were recorded for consecutive patients by interrogation of implanted Reveal monitors. Rhythm status and AF burden were quantified 6-24 months postprocedure, and compared relative to AF type, gender, age, body mass index, left atrial size, left ventricular ejection fraction, and congestive heart failure, hypertension, age >75 years, age between 65 and 74 years, stroke/TIA/TE, vascular disease (previous MI, peripheral arterial disease or aortic plaque), diabetes mellitus, female (CHA(2) DS(2) VASc). RESULTS: A total of 50 patients were enrolled with 94% having persistent or longstanding persistent AF. There were 2 atrioesophageal fistulas reported. In one patient, the fistula resulted in death at 33 days postprocedure; in the second, the fistula was surgically repaired but patient died 8 months postprocedure from a CVI. After CP, 95% of patients were in sinus rhythm at 6-month follow-up; 88% at 12 months; and 87% at 24 months. The median AF burden recorded with Reveal XT monitors was 0.0%, 0.1%, and 0.1% at 6, 12, and 24 months with 81%, 81%, and 87% of patients reporting a burden less than 3%, respectively. CONCLUSION: Using 24 × 7 continuous loop recording, the CP demonstrated success in treating persistent and longstanding persistent AF patients. Endocardial mapping and catheter ablation with diagnostic confirmation of procedural success complemented the endoscopic creation of epicardial linear lesions in restoring sinus rhythm.

Importance of evaluating conduction block in radiofrequency ablation for atrial fibrillation.

OBJECTIVE: Atrial fibrillation (AF) is the most frequently diagnosed cardiac arrhythmia. Anti-arrhythmic drugs may be used to suppress ectopic foci and interrupt reentry circuits, but are often insufficient to treat recurrent AF and have a number of adverse effects. Alternative therapies, such as catheter and surgical ablation, have been explored. This investigation examines the importance of assessing exit block when performing surgical ablation during beating-heart treatment of AF. METHODS: This was an evaluation of pooled data from multicenter prospective results obtained in AF patients who received ablation with a new, irrigated, vacuum-integrated device that creates linear lesions during beating-heart/open-chest or minimally invasive, port-access procedures. Electrocardiogram or Holter data were collected intra-operatively and at 1, 3, 6, and 12 months. Outcomes were also evaluated for patients who were or 'were not' tested for exit block following the ablation procedure. RESULTS: A total of 93 patients were treated (61 open-chest surgeries, 32 port-access procedures). There were no device-related complications and no operative mortality. At 341 days' average follow-up, 71/86 (83%) patients were free from AF, 66/86 (77%) were in sinus rhythm, and 60/86 (70%) were free from AF and off Class I and III anti-arrhythmic drugs (AADs). At 12 months, 23/23 (100%) patients with exit block confirmed were AF free compared with 13/21 (62%) patients with exit block not tested (p≤0.01, Fisher's exact test); 20/23 (87%) were in sinus rhythm compared with 12/21 (57%) patients with exit block not tested (p≤0.05, Fisher's exact test); and 20/23 (87%) were AF free without Class I and III AADs compared with 10/21 (48%) patients with exit block not tested (p≤0.01, Fisher's exact test). Both open-chest and port-access procedures yielded decreases in left-atrial size from baseline to 6 months' follow-up. Patients undergoing port-access procedures also observed an increase in left-ventricular ejection fraction, which was also significant at 6 months. CONCLUSION: Patients in whom exit block was confirmed following an ablation procedure were more likely to have successful clinical outcomes. Since testing for exit block must be performed on a beating heart, total epicardial beating-heart ablation may provide an important treatment for AF, providing intra-operative feedback indicative of long-term outcomes.

Simultaneous catheter and epicardial ablations enable a comprehensive atrial fibrillation procedure.

OBJECTIVE: Transmural and contiguous ablations and a comprehensive lesion pattern are difficult to create from the surface of a beating heart but are critical to the successful treatment of persistent, isolated atrial fibrillation. A codisciplinary simultaneous epicardial (surgical) and endocardial (catheter) procedure (Convergent procedure) addresses these issues. METHODS: Patients with symptomatic atrial fibrillation who failed medical treatment were evaluated. Using only pericardioscopy, the surgeon performed near-complete epicardial isolation of the pulmonary veins and a "box" lesion on the posterior left atrium using unipolar radiofrequency ablation. Simultaneous endocardial catheter radiofrequency ablation completed pulmonary vein isolation, performed a mitral annular and cavotricuspid isthmus line of block, and debulked the coronary sinus. Twelve-month results for the Convergent procedure were compared with 12-month results for concomitant and pericardioscopic (stand-alone transdiaphragmatic/thoracoscopic) atrial fibrillation procedures using unipolar radiofrequency ablation. RESULTS: Sixty-five patients underwent the Convergent procedure (mean age, 62 y; mean body surface area, 2.17 m²; mean atrial fibrillation duration, 4.8 y; mean left atrial size, 5.2 cm). Ninety-two percent were in persistent or long-standing persistent atrial fibrillation. At 12 months, evaluation with 24-hour Holter monitors found 82% of patients in sinus rhythm, while only 47% of pericardioscopic and 77% of concomitant patients treated with unipolar radiofrequency ablation were in sinus rhythm. CONCLUSIONS: Simultaneous epicardial and endocardial ablation improves outcomes for patients with persistent or longstanding persistent atrial fibrillation. This successful collaboration between cardiac surgeon and electrophysiologist is an important treatment option for patients with large left atriums and chronic atrial fibrillation.

Electrophysiology of anterograde right-atrial and left-atrial inputs to the atrioventricular node in patients with atrioventricular nodal re-entrant tachycardia.

AIMS: To study anterograde atrioventricular (A-V) nodal electrophysiological properties through the right-atrial (Ri) and left-atrial inputs (Li) under the pharmacological autonomic blockade (AUB) in patients with slow-fast A-V nodal re-entrant tachycardia (AVNRT) and in controls. METHODS AND RESULTS: Twenty-nine patients with slow-fast AVNRT and 15 control subjects were included. Programmed stimulation with single extrastimulus was performed from the right atrial appendage to test the Ri, and from the posterolateral coronary sinus to test the Li. The AUB was induced with intravenous atropine (0.04 mg/kg) and metoprolol (0.15 mg/kg). The A-V nodal conduction times, refractoriness, discontinuous conduction (≥ 40 ms atrial-His interval 'jump'), and inducibility of AVNRT or reciprocating beats were compared. The A-V nodal conduction times were longer: (i) through the Ri than Li, (ii) in patients than controls, and (iii) in baseline than after AUB--at slow rates in both groups and at fast rates in patients through the right input only (P < 0.05-0.001). A significantly longer slow pathway effective refractory period was demonstrated through the Li than the Ri in patients in baseline (P < 0.05). The discontinuous conduction was demonstrated 94 times in 25 of 29 (83%) patients and 15 times in 6 of 15 (40%) controls (P < 0.01), and was most frequently encountered with the Ri testing. Likewise, inducibility was manifested most frequently with the Ri testing (P = 0.08), and decreased after AUB during this testing only (P = 0.05). CONCLUSION: The inherent magnitude of discordance of A-V nodal conduction velocity, refractoriness, and parasympathetic modulation between the Ri and Li to the A-V node may play a role in the aetiology of AVNRT.

Impact of catheter ablation of the coronary sinus on paroxysmal or persistent atrial fibrillation.

OBJECTIVES: This study evaluated the impact of catheter ablation of the coronary sinus (CS) region during paroxysmal and persistent atrial fibrillation (AF). BACKGROUND: The CS musculature and connections have been implicated in the genesis of atrial arrhythmias. METHODS: Forty-five patients undergoing catheter ablation of AF were studied. The CS was targeted if AF persisted after ablation of pulmonary veins and selected left atrial tissue. CS ablation was commenced endocardially by dragging along the inferior paramitral left atrium. Ablation was continued from within the vessel (epicardial) if CS electrograms had cycle lengths shorter than that of the left atrial appendage. RF energy was limited to 35 W endocardially and 25 W epicardially. The impact of ablation was evaluated on CS electrogram cycle length (CSCL) and activation sequence, atrial fibrillatory cycle length measured in the left atrial appendage (AFCL) and on perpetuation of AF. RESULTS: Endocardial ablation significantly prolonged CSCL by 17 +/- 5 msec and organized the CS activation sequence (from 13% of patients before to 51% after ablation); subsequent epicardial ablation further increased local CSCL by 32 +/- 27 msec (P < 0.001). AFCL prolonged significantly both during endocardial and epicardial ablation (median: 152 to 167 msec P = 0.03) and was associated with AF termination in 16 (35%) patients (46% of paroxysmal and 30% of persistent AF). AFCL prolongation > or =5 msec and/or AF termination was associated with more rapid activity in the CS region originally: P < or = 0.04. CONCLUSION: Catheter ablation targeting both the endocardial and epicardial aspects of the CS region significantly prolongs fibrillatory cycle length and terminates AF persisting after PV isolation in 35% of patients.