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Purkinje fibers play an important role in initiation and maintenance of ventricular fibrillation (VF) and polymorphic ventricular tachycardia (PMVT). Fascicular substrate modification (FSM) approaches have been suggested to treat recurrent VF in case reports and small case series.

High-voltage pulses can cause hemolysis.

Studies have reported development of pulmonary hypertension (PH) secondary to reduced LA compliance following AF ablation.

Acute pericarditis is a known complication of ablation procedures for atrial fibrillation (AF).

This study evaluated the association of the post-ablation scar with stroke risk in patients undergoing atrial fibrillation (AF) ablation.

We investigated the ablation success of scar homogenization with combined (epicardial + endocardial) vs endocardial-only approach for ventricular tachycardia (VT) in patients with ischemic cardiomyopathy (ICM) at 5 years of follow-up.

Obesity, a known risk factor for atrial fibrillation (AF), is potentially reversible through lifestyle changes including diet and physical activity. However, lack of compliance is a major obstacle in attaining sustained weight-loss. We investigated the impact of patient engagement using a digital monitoring system, on compliance for lifestyle-change measures and subsequent outcome.

Background:Hemodynamically unstable VT is seen in about 50-80% of patients with structural heart disease. Use of anesthesia, induction of VT and fluid overload during catheter ablation can worsen the hemodynamic instability in these patients. Mechanical circulatory support is believed to be helpful in avoiding adverse outcomes during the ablation procedure. We report our experience in a series of high-risk patients identified by the PAAINESD score, undergoing substrate-based VT ablation.Methods:Consecutive high-risk patients undergoing substrate-based VT ablation at our center were included in the analysis. High-risk was defined as the mean PAAINESD score of 17 or higher. PAAINESD risk score includes the following variables: chronic obstructive Pulmonary disease (5 points); Age >60 years (3 points); general Anesthesia (4 points); Ischemic cardiomyopathy (6 points); NYHA functional class III or IV (6 points); Ejection fraction <25% (3 points); presentation with VT Storm (5 points); and Diabetes mellitus (3 points). Hemodynamic instability was defined as a mean arterial pressure of <45 mmHg without mechanical circulatory support. In case of hemodynamic collapse, use of support device was considered.Results:Of the 190 patients screened, 33 were identified as high risk with mean PAAINESD score of 19.8?2.3. One of the 33 patients (3%) with the risk score of 27, required hemodynamic support for which implantable left ventricular assist device was utilized. Subsequently, the procedure was cancelled in this patient as the mean arterial pressure remained < 45 mm Hg in spite of the hemodynamic support. In the remaining 32 (97%) patients, VT ablation was successfully completed without any support. No procedural complications were recorded in these 32 patients.Conclusions:In majority of the high-risk patients, substrate-based VT ablation could be safely performed without using any hemodynamic support.

Background:Prior studies have reported an approximate 4% increase in new-onset atrial fibrillation (AF) with each unit increase in the body mass index (BMI), when BMI is investigated as a continuous variable.Objective:To assess the association BMI with hypertension (HTN), diabetes (DM), sleep apnea (OSA) and prevalence of left atrial (LA) scar along with long-term ablation success in AF patients undergoing catheter ablationMethods:Based on the baseline BMI, 4,236 consecutive AF patients undergoing AF ablation were classified into group I: BMI ?25 (n=975), group II: BMI 26-35 (n=2507) and group III: BMI >35 (n=754). Documented clinical diagnosis was accepted as evidence for presence of HTN, OSA or DM. LA scarring (bipolar voltage amplitude <0.5 mV) was determined by 3D voltage mapping. All received isolation of pulmonary veins, LA posterior wall and superior vena cava. Moreover, sustained non-PV triggers were ablated upon detection by isoproterenol challenge. Patients were followed up with quarterly arrhythmia monitoring for recurrence.Results:Baseline characteristics and the correlation of BMI classes with the endpoints is presented in the figure. An increase in the rate of HTN, DM and OSA was observed with increase in the BMI, which was significantly different (p<0.001) across the groups. Additionally, scar prevalence in group III was significantly higher than that in the other two groups (p=0.002). However, the recurrence rate off-antiarrhythmic drugs at 1-year follow-up after single procedure was comparable across the BMI classes.Conclusion:Our findings demonstrated higher BMI to be associated with increase in the rate of HTN, OSA, DM and LA scar, although it did not influence the ablation outcome in patients with atrial fibrillation. Our extensive ablation strategy could be the possible reason for this comparable outcome.Figure:

Background:Earlier studies have reported not just anatomic proximity but also direct contact with no intervening adipose tissue between the esophagus and the mid coronary sinus (CS) in a sizable proportion of AF patients. This close topographic relationship raises the risk of potential thermal injury to esophagus during application of radiofrequency energy in the CS. We evaluated the esophageal complications secondary to CS ablation in AF patients undergoing catheter ablation at our center.Methods:Consecutive AF patients receiving CS ablation were included in the analysis. The endocardial ablation was performed using up to 40W power; duration of lesion at each ablation site was 5-10 sec and a contact force of <10g was used. Ablation was always started distally and the ablation catheter was continuously dragged back to the CS Os, making sure that the catheter tip was freely moving, to avoid steam pops. An esophageal probe was used to continuously monitor the luminal temperature; it was advanced while ablating the CS and if the temperature was seen to be rising fast and above 38-39?C, RF delivery was discontinued. Patients were followed up closely for all potential complications including any symptoms pertaining to esophageal injury.Results:A total of 5337 patients (age 66.7?10.2, paroxysmal AF 28%, male 68.7%) receiving focal ablation/isolation of CS were included in the analysis. Cardioesophageal fistula was reported in 1 (1/5337, 0.02%) patient. In this particular case, inadvertently the esophageal probe was not advanced during the CS ablation and thus the temperature was not monitored accurately. Twelve days after the procedure, the patient presented with symptoms of fistula that was confirmed by CT scan. He received stent for closure of the fistula and recovered completely after 3 weeks of antibiotics and other supportive therapy. No other complications secondary to CS ablation (i.e. injury to the AV node evidenced by intra-procedural PR prolongation) were reported in the study population.Conclusion:Thermal esophageal injury following CS ablation is rare even with high power ablation as long as the lesion duration is kept at 5-10 sec and continuous monitoring of the esophageal temperature is diligently performed.

Introduction:Atrial fibrillation (AF) is known to promote thrombus formation in the left atrium and thus increases the risk of stroke. The best rhythm-control strategy, anti-arrhythmic drugs (AAD) or catheter ablation, still remains controversial especially in non-paroxysmal AF patients. We sought to compare the rate of thromboembolic (TE) events in AF patients receiving catheter ablation with published stroke rate in patients treated with AAD.Methods:A total of 2741 consecutive paroxysmal or persistent AF patients receiving catheter ablation at our center were included in the analysis and prospectively followed up for 3 years. All patients received isolation of the pulmonary veins, left atrial posterior wall and empiric isolation of the superior vena cava as our standard procedure. Oral anticoagulation was prescribed for 6 months post-ablation after which it was discontinued in all patients remaining arrhythmia-free. Patients were followed up for thromboembolic events that included ischemic stroke and transient ischemic attack (TIA). Stroke was defined as the onset of a new neurological deficit that persisted for >24 hours. If the duration of the deficit was <24 hours, it was defined as TIA. We compared the post-ablation stroke rate in our population with the rate reported in the ?other AAD? group in the ROCKET-AF trial (Heart Rhythm. 2014; 11(6): 925-932) where outcome of AAD therapy (other than amiodarone) in anticoagulated AF patients was described. We selected the ?other AAD? group for comparison because none of our patients received amiodarone after the ablation procedure.Results:The ?other AAD? group of the ROCKET-AF trial included 537 patients (319, 59.4% paroxysmal AF) whereas our study population had 1124 (41%) paroxysmal AF. Baseline CHADS2 score was comparable between the two populations; 3.3?0.9 and 3.36 ?0.5 in the AAD group and our population respectively. At 3 years follow-up, 10/2741 (0.36%) events were reported in the catheter ablation cohort and 8/537 (1.5%) in the AAD population (p=0.001).Conclusion:In paroxysmal and persistent AF patients, catheter ablation was associated with significantly lower stroke rate than the anti-arrhythmic drug therapy combined with oral anticoagulation.

Background:Creating a durable radiofrequency lesion depends upon the power and the duration of RF energy delivery, the degree of catheter tissue contact and catheter stability. Several studies have reported the feasibility of catheter ablation using high power, short duration (HPSD) delivery of RF energy. We evaluated the locations of recovered conduction following HPSD ablation, in patients undergoing repeat catheter ablation (CA) for recurrent atrial fibrillation (AF).Methods:Consecutive AF patients undergoing repeat CA at our center were screened and those who received HPSD ablation at the prior procedure were included in the current series. HPSD ablation was defined as ablation with maximum temperature setting at 420C and power delivery at 45 W for 10-15 seconds (reduced to 5 seconds near the esophagus) with contact force of <15 grams. A temperature probe was routinely used to monitor the luminal esophageal temperature. Ablation was performed using 3.5-mm irrigated-tip catheter guided by circular mapping catheter, intra-cardiac echocardiography and a 3-D mapping system.Results:A total of 1359 AF patients (age: 66.1?9.5 years, male: 911, 67%, non-paroxysmal AF: 869, 64%) receiving redo ablation were included in this analysis. At the prior procedure with the HPSD approach, mean duration of ablation was significantly shorter in the area facing the esophagus compared to elsewhere (5.2?1.5 vs 12.5?1.7 seconds, p<0.001). At the redo, PV and posterior wall reconnection was identified in 190 (14%) patients of which 175 (92%) had the recovered conduction detected in the area facing the esophagus.Conclusion:Following the high power short duration energy delivery approach, recovery of PV and posterior wall conduction was frequently seen in the area facing the esophagus, which could be attributed to the significantly shorter duration of energy delivery in that region. Thus, strategies to displace the esophagus to enable the operators to increase the duration of energy delivery should be considered to improve ablation outcome.

Introduction:Procedure-outcome after catheter ablation in long-standing persistent atrial fibrillation (LSPAF) patients is reported to be highly variable with different ablation approaches. Metabolic syndrome (MS), a pro-inflammatory state, is also considered to be closely associated with recurrent AF. We evaluated the long-term outcome with different ablation strategies in patients with coexistent MS and LSPAF.Methods:Consecutive patients with LSPAF and MS undergoing their first catheter ablation were classified into two groups; group 1:standard ablation: PVAI extended to the entire posterior wall (PW) plus empirical isolation of superior vena cava (SVC) and group 2:standard ablation+ ablation of non-PV triggers. Ablation strategy was based on operators? discretion. In order to attenuate the between-group imbalance of the baseline covariates, a propensity score-matching technique was used resulting in 102 and 408 (1: 4) patients in gr 1 and 2 respectively. Arrhythmia-monitoring was performed quarterly for 1 year and biannually afterwards. Long-term success was assessed off-antiarrhythmic drugs (AAD).Results:All patients received PVAI plus isolation of left atrial PW and SVC (standard ablation). Following the standard ablation, high-dose isoproterenol challenge (25-30 ?g/min for 10-15 min) was performed in group 2 (n=408) patients to identify non-PV triggers. These were detected and ablated in LAA (277, 68%), CS (298, 73%), inter-atrial septum (119, 29%) and crista terminalis (72, 17.6%). Isoproterenol challenge was not performed in group 1 (n=102) patients. Procedural complications included 1 (0.98%) and 3 (0.73%) groin hematomas in group 1 and 2 respectively (p=NS). At the end of 2 years of follow-up, 18 (17.6%) from group 1 and 253 (62%) patients from group 2 were arrhythmia free off-AAD (p<0.001)Conclusion:In our study patients with LSPAF and metabolic syndrome, standard ablation plus ablation of all detectable non-PV triggers during the first procedure was demonstrated to be significantly more effective in achieving long-term arrhythmia-free survival compared to standard ablation alone.