INTRODUCTION:The IMPACT study established the role of controlled esophageal cooling in preventing esophageal thermal injury during radiofrequency (RF) ablation for atrial fibrillation (AF). The effect of esophageal cooling on ablation lesion delivery and procedural and patient outcomes had not been previously studied. The objective was to determine the effect of esophageal cooling on the formation of RF lesions, the ability to achieve procedural endpoints, and clinical outcomes.METHODS:Participants in the IMPACT trial underwent AF ablation guided by Ablation Index (30 W at 350-400 AI posteriorly, 40 W at ≥450 AI anteriorly). A blinded 1:1 randomization assigned patients to the use of the ensoETM® device to keep esophageal temperature at 4°C during ablation or standard practice using a single-sensor temperature probe. Ablation parameters and clinical outcomes were analyzed.RESULTS:Procedural data from 188 patients were analyzed. Procedure and fluoroscopy times were similar, and all pulmonary veins were isolated. First-pass pulmonary vein isolation and reconnection at the end of the waiting period were similar in both randomized groups (51/64 vs. 51/68; p = 0.54 and 5/64 vs. 7/68; p = 0.76, respectively). Posterior wall isolation was also similar: 24/33 versus 27/38; p = 0.88. Ablation effect on tissue, measured in impedance drop, was no different between the two randomized groups: 8.6Ω (IQR: 6-11.8) versus 8.76Ω (IQR: 6-12.2; p = 0.25). Arrhythmia recurrence was similar after 12 months (21.1% vs. 24.1%; 95% CI: 0.38-1.84; HR: 0.83; p = 0.66).CONCLUSIONS:Esophageal cooling has been shown to be effective in reducing ablation-related thermal injury during RF ablation. This protection does not compromise standard procedural endpoints or clinical success at 12 months.

In a deep gas drilling project, the 22-in section across shallow fractured carbonates is drilled using an unweighted clay-water system incorporating up to 50-lbm/bbl bentonite. The main challenges comprise lost circulation, tight hole, and low penetration rates due to high clay content and lack of inhibition, resulting in geological complications and affecting the well delivery time. To seal off the large fractures in the lower-cretaceous limestones, the new drilling fluid was engineered with high thixotropic characteristics presenting a flat, shear-thinning rheological profile with low plastic viscosity, high yield point and flat gel strengths. The selection of candidate wells was supported by offset wells analysis considering drilling performance, penetration rate and footage achieved, and the likelihood of encountering losses. Fine-tuning of the fluid rheology was performed to effectively account for the probability of losses on each well and a fit-for-purpose drilling fluid formulation was designed. This innovative technology combining mixed-metal oxide with premium bentonite was run in a series of wells as a substitute to the previously used system. Due to its superior viscosity at low shear rates the fluid successfully prevented losses by gelling up in the interstices of the highly fractured limestone intervals. In addition, the fluid delivered higher drilling performance across the abrasive sandstone-clay intercalations and the hard carbonates toward the bottom of the section. By maintaining full circulation all way through and therefore avoiding the expenses associated with blind drilling and pumping mud cap, the initiative resulted in considerably lowering the fluid cost in this section. Significant operation time savings were also achieved by drilling the section faster to the intended casing point in a minimum number of runs. Enhanced wellbore condition that allowed the drill string to trip out on elevators instead of back-reaming also contributed to saving rig time. The casing could be run to bottom and cemented trouble free in one stage with cement returns to surface thus precluding the cost of stage collar tool in most of the wells. This paper unveils the facets of this versatile water-base fluid that was introduced as a solution to prevent losses and address poor drilling performance.

COVID-19 causes severe illness that results in morbidity and mortality. Electrocardiographic features, including QT prolongation, have been associated with poor acute outcomes; data on the medium-term outcomes remain scarce. This study evaluated the 1-year outcomes of patients who survived the acute COVID-19 infection. Methods and Materials: Data of the 159 patients who survived the COVID-19 illness during the first wave (1 March 2020–18 May 2020) were collected. Patient demographics, laboratory findings and electrocardiography data were evaluated. Patients who subsequently died within 1-year of the index illness were compared to those who remained well. Results: Of the 159 patients who had survived the index illness, 28 (17.6%) subsequently perished within 1-year. In comparison to the patients that were alive after 1-year, the deceased were older (68 vs. 83 years, p < 0.01) and equally male (60.4% vs. 53.6%, p = 0.68), with a similar proportion of hypertension (59.5% vs. 57.1%, p = 0.68), diabetes (25.2% vs. 39.2%, p = 0.096) and ischaemic heart disease (11.5% vs. 7.1%, p = 0.54). The QTc interval for the alive and deceased patients shortened by a similar degree from the illness to post-COVID (−26 ± 33.5 vs. −20.6 ± 30.04 milliseconds, p = 0.5); the post-COVID R-R interval was longer in the alive patients compared to the deceased (818.9 ± 169.3 vs. 761.1 ± 61.2 ms, p = 0.02). A multivariate Cox regression analysis revealed that age (HR1.098 [1.045–1.153], p < 0.01), diabetes (HR3.972 [1.47–10.8], p < 0.01) and the post-COVID R-R interval (HR0.993 [0.989–0.996], p < 0.01) were associated with 1-year mortality. Conclusions: The COVID-19-associated mortality risk extends to the post-COVID period. The QTc does recover following the acute illness and is not associated with outcomes; the R-R interval is a predictor of 1-year mortality.

Background With an increasing number of cardiac implantable electronic devices (CIEDs), there has been a paralleled increase in demand for transvenous lead extraction (TLE). Cardiac surgeons (CS) and cardiologists perform TLE; however, data comparing the two groups of operators is scarce. Objective We compared the outcomes of TLE performed by cardiologists and CS from six European lead extraction units. Method Data was collected retrospectively of 2205 patients who had 3849 leads extracted (PROMET) between 2005 and 2018. Patient demographics and procedural outcomes were compared between the CS and cardiologist groups, using propensity score matching. A multivariate regression analysis was also performed for variables associated with 30-day mortality. Results CS performed the majority of extractions (59.8%), of leads with longer dwell times (90 [57-129 interquartile range (IQR)] vs. 62 [31-102 IQR] months, CS vs. cardiologists, p < .001) and with pre-dominantly non-infectious indications (57.4% vs. 50.2%, CS vs. cardiologists, p < .001). CS achieved a higher complete success per lead than the cardiologists (98.1% vs. 95.7%, respectively, p < .01), with a higher number of minor complications (5.51% vs. 2.1%, p < .01) and similar number of major complications (0.47% vs. 1.3%, p = .12). Thirty-day mortality was similarly low in the CS and cardiologist groups (1.76% vs. 0.94%, p = .21). Unmatched data multivariate analysis revealed infection indication (OR 6.12 [1.9-20.3], p < .01), procedure duration (OR 1.01 [1.01-1.02], p < .01) and CS operator (OR 2.67, [1.12-6.37], p = .027) were associated with 30-day mortality. Conclusion TLE by CS was performed with similar safety and higher efficacy compared to cardiologists in high and medium-volume lead extraction centers.

Background Cardiac implantable electronic device (CIED) therapy contributes to an improvement in morbidity and mortality across all patient demographics. Patient age is a recognized risk factor for unfavorable outcomes in invasive procedures. This is the largest series of non-laser transvenous lead extraction (TLE) evaluating the association between patient age and procedure outcomes. Methods Data of 2205 (3849 leads) patients was collected retrospectively from six European TLE centers between January 2005-December 2018 in the PROMET study. Of these, 153 patients with 319 leads were excluded for incomplete data. A comparison of outcomes was performed between the age groups young [< 50 years], young intermediate [50-69 years], older intermediate [70-79 years], and octogenarian [>= 80 years]. Results Infection was most common indication for TLE in the octogenarian cohort, less common in the younger population (60.1% vs. 33.2%, respectively, p < .01). High-voltage leads were extracted most frequently from young patients, less frequently from octogenarians (31.6% vs. 10%, p < .001), while the opposite was evident for pacemaker leads (p < .001). Rotational sheath use was equally prevalent across all patient groups (p = .79). Minor and major complications across all the age groups were statistically similar, as was procedural success; the 30-day mortality was most significant in the octogenarian and least in the young patients (4.9% vs. 0.4%, p = .005). Propensity matching multivariate analysis found systemic infection, lead dwell time, and patient age (p = .013, OR 1.064 [1.013-1.116]) increased risk of 30-day mortality. Conclusion TLE is safe and effective across all age groups. 30-day mortality risk is significantly higher in the older patients.

Abstract Funding Acknowledgements Type of funding sources: None. Background Cardiac perforation is an uncommon but life-threatening complication of cardiac implantable electronic device (CIED) implantation. Management strategy commonly relies on diagnostic Computed Tomography (CT) imaging and cardiac surgery. Emerging evidence has indicated a diversion from this approach. Transvenous culprit lead revision has been shown to be safe and efficacious in limited series. We sought to evaluate the outcomes of transvenous lead revision in patients with cardiac perforation. Method Data was collected retrospectively of patients admitted to a single tertiary centre with CIED-related cardiac perforation between December 2013 – October 2019. Transvenous lead revision was performed as standard with cardiac surgery on standby. Patient demographics, use of CT imaging, method of removal and 30-day outcomes were recorded. Results Of the 46 recorded CIED-related cardiac perforations, the majority occurred in female patients (63%) and hypertensives (61%), whilst a proportion had cancer (20%) and ischaemic heart disease (30%). The culprit in most cases was a standard pacing lead (92%) of an active fixation (98%) in the right ventricle (80%) positioned at the ventricular apex (65%). The median time to presentation from implant was 14 days [IQR 4-50 days] with chest pain (44%); abnormal pacing indices was highly prevalent (95%) whilst a pericardial effusion was noted in the majority of cases (57%). CT scanning was performed in 19 cases (41%) for various indications but deemed essential in only 4, all of which had non-diagnostic pacing indices and imaging. Chest X-ray (CXR) found clear perforation, lead displacement or pleural effusion in 74% of cases, whilst an echocardiogram found these in 64% of cases. The culprit lead was replaced in the majority of cases (87%) under local anaesthesia (76%) with surgical backup. The median hospital stay was 7 days [IQR 3-10 days] with zero procedural and 30-day mortality. Conclusion Transvenous lead revision for CIED-related cardiac perforation is safe and efficacious. CT modality for diagnostic purposes is useful in providing incremental value in a minority of cases; patients with non-diagnostic pacing parameters and non-CT imaging benefit most from this.

Abstract Funding Acknowledgements Type of funding sources: None. OnBehalf PROMET group Background Cardiac implantable electronic devices (CIEDs) improve morbidity and mortality. This has fuelled an upsurge in implantation of these devices across all patient cohorts, simultaneously increasing the need for transvenous lead extractions (TLE). As the global population expands and life-expectancy extends, TLE will play a significant role in CIED management. Advancing patient age is a recognised risk factor for poor outcomes however the association between patient age and TLE outcomes remains unclear. We sought to evaluate the relationship between patient age and non-laser TLE outcomes. Method Data of 2205 patients (3849 leads) was collected retrospectively from six high-volume TLE institutes across Europe (PROMET) between January 2005-December 2018. Propensity 1:1 score matching was performed to limit the effects of confounding variables, pairing 353 patients in the >80 years of age category with 353 patients in <80 years of age group. Procedural outcomes were compared between the two age groups and multivariate regression analysis was used for predictors of 30-day mortality. Results In the <80 and >80 years-of-age cohorts, there was a similar proportion of male patients (65.3% vs 67.9%, p = 0.47) treated under general anaesthesia (96.5% vs 93.4%, p = 0.078) for a pre-dominant infectious indication (56.7% vs 60.3%, p = 0.52) but with a higher requirement of the EvolutionTM sheath in the octogenarians (39.4% vs 48.4%, p = 0.015). A similar clinical success per lead was achieved between the two age groups (96.6% vs 98%, <80 vs >80 years, p = 0.245) as was complete lead extraction (95.5% vs 96.6%, <80 vs >80 years, p = 0.44) with a comparable minor complication rate (2.3% vs 3.1%, <80 vs >80 years, p = 0.29) and major complications (1.1% vs 1.4%, <80 vs >80 years, p = 0.74). Thirty-day mortality was higher in the octogenarian cohort than the <80-year-olds without reaching statistical significance (5.4% vs 2.6%, p = 0.08); peri-procedural mortality was similar in both age groups (0.3% vs 0.6%, respectively, p = 0.56). Multivariate regression analysis revealed age (p = 0.013, OR 1.06 [1.01-1.12]), systemic infection (p = 0.026, OR 3.4 [1.16-10.35]) and lead dwell time (p = 0.007, OR 1.01 [1.003-1.017]) increased the odds of 30-day mortality. Conclusion Transvenous lead extraction is similar in efficacy and safety across all age groups. Thirty-day mortality is higher in the advanced age group, signifying the importance of post-procedural management in this cohort.

Abstract Funding Acknowledgements Type of funding sources: None. OnBehalf PROMET group Background As implantation of cardiac implantable devices (CIED) rises globally, there is a paralleled need for extraction of these devices. Indications for transvenous lead extraction (TLE) is expanding, fuelling demand. This lifesaving procedure is performed by cardiologists and cardiac surgeons (CS). Cardiologists are familiar with transvenous methods whilst cardiac surgeons possess the skillset to address the significant complications associated with this procedure. We compared non-laser TLE outcomes performed by cardiologists and cardiac surgeons from six high-volume extraction centres across Europe. Methods Data was collected retrospectively from six major European TLE centres of 2205 patients and 3849 leads (PROMET). Propensity 1:1 score matching (PSM) was performed to account for confounding variables. PSM model with variables: lead dwell time, infection indication, biventricular system and defibrillator device, was best matched. This dataset was analysed to compare outcomes of TLE performed by the cardiologists and CS. Predictors of 30-day mortality and complications were identified using a multivariate regression analysis. Results Patients treated by CS and cardiologists were similar in age (64.7 vs 66.7 years, p = NS) and equally male (70.3% vs 72.3%, p = 0.39) with a parallel infectious indication (51.7% vs 47.6%, p = 0.1). Surgeons achieved a significantly higher proportion of clinical success than cardiologists (98.9% vs 96.4%, p = 0.001) and complete lead extraction (98% vs 95.9%, p < 0.01) with a higher rate of minor complications (4.1% vs 2.2%, p = 0.024); major complications were similar (0.9% vs 1.2%, respectively, p = 0.46) as was 30-day mortality (3.2% vs 2%, respectively, p = 0.28). Multivariate regression analysis revealed systemic infection (p < 0.001, OR 7.2 [CI 2.3-20.1]) and defibrillator system extraction (p = 0.025, OR 3.4 [CI 1.2-10.2]) increased the odds of 30-day mortality, whilst Evolution™ sheath use reduced the odds (p = 0.025, OR 0.34 [CI 0.13-0.88]); lead dwell time (p = 0.02, OR 1.005 [1-1.009] and Evolution™ sheath use (p = 0.023, OR 2.15[1.1-4.15]) increased the odds of complications. Conclusion Cardiac surgeons and cardiologists achieved a high rate of TLE procedural success and with a similar safety profile, replicating standards seen across Europe.

Abstract Background Left atrial posterior wall (LAPW) isolation is an adjunct to pulmonary vein isolation (PVI) for persistent atrial fibrillation (AF). Objective To compare the effect of LAPW box isolation with LAPW point-by-point ablation and PVI in persistent AF on 12-month arrhythmia-free survival and procedure complications. Methods 77 consecutive patients who underwent LAPW box isolation, 24 patients who underwent LAPW point-by-point ablation and 101 patients who underwent PVI for persistent AF were compared. All patients had undergone no prior ablation for AF and were followed up for one year. Results Mean time to atrial tachyarrhythmia recurrence was similar with LAPW box isolation (9.8 months, 95% CI = 9-10.7) and LAPW point-by-point ablation (10 months, 95% CI = 8.6-11.3), both were longer than PVI (8.2 months, 95% CI = 7.4-9.1, log-rank p = 0.003). There was no difference in peri-procedural complications (LAPW box isolation: 5/77, LAPW point-by-point ablation: 1/24, PVI: 6/101, p = 0.91). At 12 months, no difference in atrial tachyarrhythmia recurrence was observed between box isolation (23/77, 30%) and point-bypoint ablation (11/24, 46%, p = 0.15), but significantly higher recurrence occurred with PVI alone (58/101, 57%, p < 0.001). Procedure time was similar with both approaches, with longer fluoroscopy with point-by-point ablation (median: 38 min, IQR: 29-47.75) vs box isolation (median: 28 min, IQR: 7.5-39.5, p = 0.2). Conclusion In persistent AF, there was no difference between LAPW box isolation and point-by-point ablation in terms of mean arrhythmia-free survival, 12-month recurrence or procedure complications. Arrhythmia-free survival with either technique was longer than PVI alone, with no increase in complications.

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.

Cardiac implantable electronic device (CIED)‐related perforation is uncommon but potentially lethal. Management typically includes the use of computed tomography (CT) scanning and often involves cardiac surgery.

Background Coronavirus disease-2019 (COVID-19) causes severe illness and multi-organ dysfunction. An abnormal electrocardiogram is associated with poor outcome, and QT prolongation during the illness has been linked to pharmacological effects. This study sought to investigate the effects of the COVID-19 illness on the corrected QT interval (QTc). Method For 293 consecutive patients admitted to our hospital via the emergency department for COVID-19 between 01/03/20 -18/05/20, demographic data, laboratory findings, admission electrocardiograph and clinical observations were compared in those who survived and those who died within 6 weeks. Hospital records were reviewed for prior electrocardiograms for comparison with those recorded on presentation with COVID-19. Results Patients who died were older than survivors (82 vs 69.8 years, p < 0.001), more likely to have cancer (22.3% vs 13.1%, p = 0.034), dementia (25.6% vs 10.7%, p = 0.034) and ischemic heart disease (27.8% vs 10.7%, p < 0.001). Deceased patients exhibited higher levels of C-reactive protein (244.6 mg/L vs 146.5 mg/L, p < 0.01), troponin (1982.4 ng/L vs 413.4 ng/L, p = 0.017), with a significantly longer QTc interval (461.1 ms vs 449.3 ms, p = 0.007). Pre-COVID electrocardiograms were located for 172 patients; the QTc recorded on presentation with COVID-19 was longer than the prior measurement in both groups, but was more prolonged in the deceased group (448.4 ms vs 472.9 ms, pre-COVID vs COVID, p < 0.01). Multivariate Cox-regression analysis revealed age, C-reactive protein and prolonged QTc of >455 ms (males) and >465 ms (females) (p = 0.028, HR 1.49 [1.04-2.13]), as predictors of mortality. QTc prolongation beyond these dichotomy limits was associated with increased mortality risk (p = 0.0027, HR 1.78 [1.2-2.6]). Conclusion QTc prolongation occurs in COVID-19 illness and is associated with poor outcome.

Atrial Fibrillation (AF) is very common among patients with severe aortic stenosis. Moreover, new onset AF (NOAF) is a frequent finding after Transcatheter Aortic Valve Replacement (TAVR). There is a significant impact of AF on outcomes in patients undergoing TAVR including mortality, thrombo-embolic and bleeding events. There is lack of clear evidence about the optimal management of AF in TAVR patients. This review aims to summarize the epidemiology, predictors, prognosis, therapeutic considerations and challenges in the management of AF in patients undergoing TAVR.

As operators are drilling more and more complex wells in technically demanding basins; they are also looking to be cost effective and to minimize impact on the environment. This has driven the industry in recent past to develop and use high-performance water-based drilling fluids (HPWBDF). A drilling fluid that has performance like oil-based drilling fluids and environmental acceptance of water-based drilling fluids is the need of the times. In the whole Gulf region, wellbore instability is a major cause of nonproductive time. Drilling time-dependent shale formations have always been challenging; hole instability, tight hole, back reaming, and well packoff have been experienced in both vertical and highly deviated wells. These formations have a combination of reactive and dispersive clays in the shale formation, interbedded formation sequences, microfractures, and sometimes they can be tectonically stressed and overpressured with high-stress anisotropy. Such features make these formations time sensitive and highly unstable, thus they need multiple levels of inhibition. For this reason, oil-based drilling fluids are fluids of choice for many operators. In current times, the exceptional drillability of nonaqueous drilling fluids in high-angle, long-reach horizontal wells is offset by tremendously high logistical and waste-management costs that can account for half of the total drilling fluids cost. Recognizing these challenges, a novel HPWBDF was developed that could provide high level of inhibition and an excellent environmental and logistical footprint. This paper presents a successful application of a new HPWBDF using a unique triple inhibition approach. The system exceeded customer's requirements by successful execution of all well objectives. The client used this system in three consecutive sections instead of the single planned section. This solution has the potential to be used as an alternative to oil-based fluids in all similar formations drilled across the Middle East.

Cardiac perforation caused by cardiac rhythm device implantation is uncommon but potentially lethal. All patients presenting to a single referral centre with cardiac perforation after implantation between December 2017 and July 2019 were identified. Patient demographics, time to diagnosis, the method of lead extraction and 30-day complications were examined. Thirteen cases of cardiac perforation were identified, 4 of which were implanted at other hospitals. The incidence of perforation for devices implanted at our institution was 9/1031 (0.87%). Median time from implantation to diagnosis was 8 days (IQR = 3–21). Compared with implantations during the same time period, patients with perforation were older (80 ± 10 years vs. 73 ± 15 years, P = 0.005) and predominantly females (9/13 vs. 355/1031, P = 0.009). In all cases, the perforating lead was an active fixation model, an ICD coil in one case. 10 leads were in the right ventricle (3 of which in apical position) and 3 in the right atrium (all in the lateral wall). There was no greater proportion of a particular lead type compared with implantations during the same time period. All had abnormal electrical parameters at device interrogation. Nine patients (69%) had pericardial effusion and four (31%) developed tamponade. Transvenous lead extraction was successfully performed in all 13 patients, with no 30-day mortality. Older age and female gender were more prevalent in patients with lead perforation. Transvenous lead extraction was safely performed in all patients.

Extensive atrial ablation in the setting of atrial fibrillation (AF) and atrial tachycardia (AT) can affect interatrial connections. A 76-year-old man with a history of tachycardia-induced cardiomyopathy and nine ablation procedures for AF/AT over 15 years presented with highly symptomatic recurrent AT. Previous ablation lesions included pulmonary vein isolation, left atrial posterior wall isolation, mitral isthmus line, cavotricuspid isthmus line, and the ablation of areas of fractionated electrograms. Electroanatomical mapping found the pulmonary veins and the left atrial posterior wall to be silent, as was the posterior interatrial septum and the mitral isthmus area. Activation mapping showed progression of electrograms in the left atrial appendage (LAA) from the septal aspect posteriorly, and in the coronary sinus from proximal to distal; implying the existence of a septal circuit, where extensive fractionation was noted. This was targeted, while monitoring conduction into the LAA using a multielectrode catheter. Ablation led to prompt termination of tachycardia and simultaneous LAA isolation. Immediate cessation of ablation led to recovery of conduction into LAA. Additional lesions in the interatrial septum were required to render the tachycardia noninducible, accompanied by temporary isolation of LAA. The ablation lesion sets employed while ablating AF and left AT can block many interatrial pathways, rendering conduction dependent on muscle bundles in the interatrial septum and, therefore, vulnerable to block by lesions in this area. LAA isolation has been associated with high incidence of LAA thrombus formation and stroke despite oral anticoagulation. Continuous observation of LAA electrograms during ablation can help to avoid this complication.

Background The outcomes of pulmonary vein isolation (PVI) for persistent atrial fibrillation (AF) are suboptimal. The entire pulmonary venous component (PV-Comp), consisting of the pulmonary veins, their antra, and the area between the antra, provides triggers and substrate for AF. PV-Comp isolation is an alternative strategy for persistent AF ablation. Methods Among 328 patients with persistent AF who underwent a first radiofrequency ablation procedure, 200 patients (PVI, n = 100; PV-Comp isolation, n = 100) were selected by propensity score matching. Both groups were followed up for 1 year. Results At 6- and 12-month follow-up, atrial tachyarrhythmia (AF/atrial tachycardia) recurred in 41 and 61 patients in PVI group and 22 (P = .006) and 33 patients (P < .001) in PV-Comp isolation group, respectively. PV-Comp isolation was associated with longer mean time to recurrence (PVI: 8 months, PV-Comp isolation: 10 months, log-rank P < .001) and a lower probability of recurrence (odds ratio [OR] = 0.32; 95% confidence of interval [CI] = 0.18-0.56, P < .001), with no increase in procedural complications (PVI: 5 of 100, PV-Comp isolation: 6 of 100, P = .76). Procedure duration was longer in PV-Comp isolation group (PVI: 186 +/- 42 min, PV-Comp isolation: 238 +/- 44 min, P < .001), as well as fluoroscopy time (PVI: 22 +/- 16 min, PV-Comp isolation: 31 +/- 21 min, P = .001). Conclusion PV-Comp isolation for persistent AF reduced atrial tachyarrhythmia recurrence up to 1 year compared with PVI alone. While procedure and fluoroscopy time increased, there was no difference in procedural complications.

Catheter ablation of persistent atrial fibrillation (AF) is an evolving field. In this review, we discuss the rationale for isolation of the pulmonary venous component of the left atrium to control AF. The review describes the embryologic origin of this component and makes the important distinction between the true posterior wall and the pulmonary venous component, which forms the dome of the left atrium. Studies that have examined the role of left atrial posterior wall isolation in AF ablation have loosely referred to the pulmonary venous component as the posterior wall. We critically reexamine this nomenclature and provide a sound argument underpinned by fundamental anatomic considerations, a clear understanding of which is critical to the operator. We discuss the various techniques used in isolating this region and review the outcome data of studies targeting this region in AF ablation.