Pulmonary Vein Isolation With or Without Left Atrial Appendage Ligation in Atrial Fibrillation: The aMAZE Randomized Clinical Trial.

Importance: Left atrial appendage elimination may improve catheter ablation outcomes for atrial fibrillation. Objective: To assess the safety and effectiveness of percutaneous left atrial appendage ligation adjunctive to catheter pulmonary vein isolation for nonparoxysmal atrial fibrillation. Design, Setting, and Participants: This multicenter, prospective, open-label, randomized clinical trial evaluated the safety and effectiveness of percutaneous left atrial appendage ligation adjunctive to planned pulmonary vein isolation for nonparoxysmal atrial fibrillation present for less than 3 years. Eligible patients were randomized in a 2:1 ratio to undergo left atrial appendage ligation and pulmonary vein isolation or pulmonary vein isolation alone. Use of a 2:1 randomization ratio was intended to provide more device experience and safety data. Patients were enrolled from October 2015 to December 2019 at 53 US sites, with the final follow-up visit on April 21, 2021. Interventions: Left atrial appendage ligation plus pulmonary vein isolation compared with pulmonary vein isolation alone. Main Outcomes and Measures: A bayesian adaptive analysis was used for primary end points. Primary effectiveness was freedom from documented atrial arrythmias of greater than 30 seconds duration 12 months after undergoing pulmonary vein isolation. Rhythm was assessed by Holter monitoring at 6 and 12 months after pulmonary vein isolation, symptomatic event monitoring, or any electrocardiographic tracing obtained through 12 months after pulmonary vein isolation. Primary safety was a composite of predefined serious adverse events compared with a prespecified 10% performance goal 30 days after the procedure. Left atrial appendage closure was evaluated through 12 months after pulmonary vein isolation. Results: Overall, 404 patients were randomized to undergo left atrial appendage ligation plus pulmonary vein isolation and 206 were randomized to undergo pulmonary vein isolation alone. Primary effectiveness was 64.3% with left atrial appendage ligation and pulmonary vein isolation and 59.9% with pulmonary vein isolation only (difference, 4.3% [bayesian 95% credible interval, -4.2% to 13.2%]; posterior superiority probability, 0.835), which did not meet the statistical criterion to establish superiority (0.977). Primary safety was met, with a 30-day serious adverse event rate of 3.4% (bayesian 95% credible interval, 2.0% to 5.0%; posterior probability, 1.0) which was less than the prespecified threshold of 10%. At 12 months after pulmonary vein isolation, complete left atrial appendage closure (0 mm residual communication) was observed in 84% of patients and less than or equal to 5 mm residual communication was observed in 99% of patients. Conclusions and Relevance: Percutaneous left atrial appendage ligation adjunctive to pulmonary vein isolation did not meet prespecified efficacy criteria for freedom from atrial arrhythmias at 12 months compared with pulmonary vein isolation alone for patients with nonparoxysmal atrial fibrillation, but met prespecified safety criteria and demonstrated high rates of closure at 12 months. Trial Registration: ClinicalTrials.gov Identifier: NCT02513797.

Detection of atrial fibrillation in real world setting in patients with cryptogenic stroke and an implantable loop recorder.

INTRODUCTION: Implantable loop recorders (ILR) are used to screen for atrial fibrillation (AF) in patients with cryptogenic stroke (CS). However, there is limited real-world data regarding the long-term rate of AF detection using ILR and management consequences in patients with CS. The objective is to assess the rate of AF detection in patients with CS in a real-world study over 36 months of follow-up and its consequences on stroke prevention. METHODS: This retrospective study included patients with an ILR placed for CS at Baylor College of Medicine and Baylor St. Luke's Medical Center between January 2014 and July 2021. The primary outcome was AF detection in patients with ILR. The secondary outcome was the rate of subsequent strokes after ILR placement in patients with or without diagnosed AF. The AF detection rate in our cohort was compared to the rate in CRYSTAL-AF Trial at 36-month follow-up. The impact of AF detection on clinical management was examined. RESULTS: We identified 225 patients. 51.1% were women and 38.2% African American. Among 85 patients with ILR labeled AF, 43 patients had true AF, and 42 had incorrectly labeled AF (48.3% false positive). The estimated AF detection rate at 36 months follow-up was 28.6% (95% CI, 26.6%-30.6%). 58.1% of patients with AF were initiated on oral anticoagulation, 80.0% of whom were started on a direct oral anticoagulant. 13.8% of patients had recurrent strokes after ILR implantation; 4 of whom were diagnosed with AF. CONCLUSION: Compared to CRYSTAL-AF, the AF detection rate in our cohort is similar, but this cohort includes a higher proportion of female and African American patients. Most patients with recurrent strokes after ILR implant did not have AF during 36 months of monitoring.

Slow-pathway visualization by using voltage-time relationship: A novel technique for identification and fluoroless ablation of atrioventricular nodal reentrant tachycardia.

BACKGROUND: Atrioventricular nodal reentrant tachycardia (AVNRT) is treatable by catheter ablation. Advances in mapping-system technology permit fluoroless workflow during ablations. As national practice trends toward fluoroless approaches, easily obtained, reproducible methods of slow-pathway identification, and ablation become increasingly important. We present a novel method of slow-pathway identification and initial ablation results from this method. METHODS AND RESULTS: We examined AVNRT ablations performed at our institution over a 12-month period. In these cases, the site of the slow pathway was predicted by latest activation in the inferior triangle of Koch during sinus rhythm. Ablation was performed in this region. Proximity of the predicted site to the successful ablation location, complication rates, and patient outcomes were recorded. Junctional rhythm was seen in 40/41 ablations (98%) at the predicted site (mean, 1.3 lesions and median, 1 lesion per case). One lesion was defined as 5 mm of ablation. The initial ablation was successful in 39/41 cases (95%); in two cases, greater or equal to 2 echo beats were detected after the initial ablation, necessitating further lesion expansion. In 8/41 cases (20%), greater than one lesion was placed during initial ablation before attempted reinduction. Complications included one transient heart block and one transient PR prolongation. During follow-up (median, day 51), one patient had lower-extremity deep-vein thrombosis and pulmonary embolus, and one had a lower-extremity superficial venous thrombosis. There was one tachycardia recurrence, which prompted a redo ablation. CONCLUSIONS: Mapping-system detection of late-activation, low-amplitude voltage during sinus rhythm provides an objective, and fluoroless means of identifying the slow pathway in typical AVNRT.

Confirming pericardial access by using impedance measurements from a micropuncture needle.

BACKGROUND: Pericardial access is complicated by two difficulties: confirming when the needle tip is in the pericardial space, and avoiding complications during access, such as inadvertently puncturing other organs. Conventional imaging tools are inadequate for addressing these difficulties, as they lack soft-tissue markers that could be used as guidance during access. A system that can both confirm access and avoid inadvertent organ injury is needed. METHODS: A 21G micropuncture needle was modified to include two small electrodes at the needle tip. With continuous bioimpedance monitoring from the electrodes, the needle was used to access the pericardium in porcine models (n  =  4). The needle was also visualized in vivo by using an electroanatomical map (n  =  2). Bioimpedance data from different tissues were analyzed retrospectively. RESULTS: Bioimpedance data collected from the subcutaneous space (992.8 ± 13.1 Ω), anterior mediastinum (972.2 ± 14.2 Ω), pericardial space (323.2 ± 17.1 Ω), mid-myocardium (349.7 ± 87.6 Ω), right ventricular cavity (235.0 ± 9.7 Ω), lung (1142.0 ± 172.0 Ω), liver (575.0 ± 52.6 Ω), and blood (177.5 ± 1.9 Ω) differed significantly by tissue type (P < .01). Phase data in the frequency domain correlated well with the needle being in the pericardial space. A simple threshold analysis effectively separated lung (threshold  =  1120.0 Ω) and blood (threshold  =  305.9 Ω) tissues from the other tissue types. CONCLUSIONS: Continuous bioimpedance monitoring from a modified micropuncture needle during pericardial access can be used to clearly differentiate tissues. Combined with traditional imaging modalities, this system allows for confirming access to the pericardial space while avoiding inadvertent puncture of other organs, creating a safer and more efficient needle-access procedure.

Long-term clinical outcomes from real-world experience of left atrial appendage exclusion with LARIAT device.

BACKGROUND: Left atrial appendage closure (LAAC) with LARIAT has emerged as one of the alternatives to oral anticoagulation (OAC) in patients with nonvalvular atrial fibrillation (AF). Our aim was to study long-term outcomes in patients undergoing LARIAT procedure. METHODS: We analyzed patients screened for LARIAT device in four centers between December 2009 and June 2012. Out of these, patients who didn't undergo LAAC with the LARIAT device due to unfavorable LAA morphology and other preprocedural contraindications were included in control group. We analyzed thromboembolism, bleeding events, and mortality between LAA and control group. RESULTS: About 153 patients were screened. Out of these, 108 (70.6%) patients underwent LARIAT placement (LAA arm) and 45 (29.4%) excluded patients were included in control arm. There were no differences in CHADS2 and CHA2 DS2 -VASc score. Mean HAS-BLED score was significantly higher in the LARIAT group (3.5 ± 1.06 vs 3.09 ± 1.22, P = .04). Mean follow-up time (in years) was 6.56 ± 0.84 in LAA and 6.5 ± 1.26 in control arm. During follow-up period, the LARIAT group was associated with significantly less thromboembolic events (1.9% vs 24%, P < .001), bleeding events (9.2% vs 24.4%, P = .03), and mortality (5.6% vs 20%, P = .01) as compared with the control group. CONCLUSIONS: Long-term data from routine clinical practice from our study suggests that LAA exclusion with LARIAT device is an effective treatment in management of nonvalvular AF patients with high risk of stroke, bleeding, and mortality. Further randomized trials, such as aMAZE, will provide more insight in this expanding field.

Near-field impedance accurately distinguishes among pericardial, intracavitary, and anterior mediastinal position.

INTRODUCTION: Epicardial catheter ablation is increasingly used to treat arrhythmias with an epicardial component. Nevertheless, percutaneous epicardial access remains associated with a significant risk of major complications. Developing a technology capable of confirming proper placement within the pericardial space could decrease complication rates. The purpose of this study was to examine differences in bioimpedance among the pericardial space, anterior mediastinum, and right ventricle. METHODS: An ovine model (n = 3) was used in this proof-of-concept study. A decapolar catheter was used to collect bipolar impedance readings; data were collected between each of five electrode pairs of varying distances. Data were collected from three test regions: the pericardial space, anterior mediastinum, and right ventricle. A control region in the inferior vena cava was used to normalize the data from the test regions. Analysis of variance was used to test for differences among regions. RESULTS: A total of 10 impedance values were collected in each animal between each of the five electrode pairs in the three test regions (n = 340) and the control region (n = 145). The average normalized impedance values were significantly different among the pericardial space (1.760 ± 0.370), anterior mediastinum (3.209 ± 0.227), and right ventricle (1.024 ± 0.207; P < 0.0001). In post hoc testing, the differences between each pair of regions were significant, as well (P < 0.001 for all). CONCLUSION: Impedance values are significantly different among these three anatomical compartments. Therefore, impedance can be potentially used as a means to guide percutaneous epicardial access.

Accuracy of Voltage Signal Measurement During Radiofrequency Delivery Through the SMARTTOUCH Catheter.

INTRODUCTION: Current methods for measuring voltage during radiofrequency (RF) ablation (RFA) necessitate turning off the ablation catheter. If voltage could be accurately read without signal attenuation during RFA, turning off the catheter would be unnecessary, allowing continuous ablation. We evaluated the accuracy of the Thermocool SMARTTOUCH catheter for measuring voltage while RF traverses the catheter. METHODS AND RESULTS: We studied 26 patients undergoing RFA for arrhythmias. A 7.5F SMARTTOUCH catheter was used for sensing voltage and performing RFA. Data were collected from the Carto-3 3-dimensional mapping system. Voltages were measured during ablation (RF-ON) and immediately before or after ablation (RF-OFF). In evaluating the accuracy of RF-ON measurements, we utilized the RF-OFF measure as the gold standard. We measured 465 voltage signals. The median values were 0.2900 and 0.3100 for RF-ON and RF-OFF, respectively. Wilcoxon signed rank testing showed no significant difference in these values (P = 0.608). The intraclass correlation coefficient (ICC) was 0.96, indicating that voltage measurements were similarly accurate during RF-OFF versus RF-ON. Five patients had baseline atrial fibrillation (AF), for whom 82 ablation points were measured; 383 additional ablation points were measured for the remaining patients. The voltages measured during RF-ON versus RF-OFF were similar in the presence of AF (P = 0.800) versus non-AF rhythm (P = 0.456) (ICC, 0.96 for both). CONCLUSION: Voltage signal measurement was similarly accurate during RF-ON versus RF-OFF independent of baseline rhythm. Physicians should consider not turning off the SMARTTOUCH ablation catheter when measuring voltage during RFA.

Anatomical and electrical remodeling with incomplete left atrial appendage ligation: Results from the LAALA-AF registry.

BACKGROUND: The anatomical, electrical, and clinical impact of incomplete Lariat left atrial appendage ligation remains unclear. METHODS: We studied LAA anatomy pre- and postligation using contrast enhanced-computed tomography (CT) scans in 91 patients with atrial fibrillation (AF) who subsequently underwent catheter ablation (CA). RESULTS: Eleven patients had an incomplete exclusion (12%) with a central leak ranging from 1 to 5 mm. Despite incomplete ligation; the LAA volume were reduced by 67% postprocedurally when compared to preprocedure. In 7 patients with a leak between 1 and 3 mm, there was a 77% reduction in LAA volume beyond the ligation site suggestive of remodeling of the LAA. In 4 patients with larger (4-5 mm) leak the LAA remnants (LAARs) were slightly larger than those with smaller leaks on follow-up CT scan. Three out of the 4 demonstrated LAA electrical activity during CA and underwent isolation of the LAA ostium. Follow-up imaging showed two of these LAARs completely sealed with no communication with the left atrium. There was no significant difference in the AF recurrence rates between the patients who had a leak versus those with complete ligation (4 of 11 [36%] vs. 22 of 80 [27%]; P  =  0.6). Oral anticoagulation was discontinued in all patients with small leaks and 2 patients with large leaks that sealed completely upon follow-up imaging. There were no strokes or TIAs at 12 months. CONCLUSION: Despite incomplete LAA ligation by Lariat device there is significant anatomical and electrical remodeling that resulted in reduction in LAA size, volume, and electrical activity.

Impact of Periprocedural Colchicine on Postprocedural Management in Patients Undergoing a Left Atrial Appendage Ligation Using LARIAT.

INTRODUCTION: Left atrial appendage (LAA) can be effectively and safely excluded using a novel percutaneous LARIAT ligation system. However, due to pericardial catheter manipulation and LAA ligation and subsequent necrosis, postprocedural course is complicated by pericarditis. We intended to evaluate the preprocedural use of colchicine on the incidence of postprocedural pericardial complications. METHODS AND RESULTS: In this multicenter observational study, we included all consecutive patients who underwent LARIAT procedure at the participating centers. Many patients received periprocedural colchicine at the discretion of the physician. We compared the postprocedural outcomes of patients who received prophylactic periprocedural colchicine (colchicine group) with those who did not receive colchicine (standard group). A total of 344 consecutive patients, 243 in the "colchicine group" and 101 in the "standard group," were included. The mean age, median CHADS2VASc score, and HASBLED scores were 70 ± 11 years, 3 ± 1.7, and 3 ± 1.1, respectively. There were no significant differences in major baseline characteristics between the two groups. Severe pericarditis was significantly lower in the "colchicine group" compared to the "standard group" (10 [4%] vs. 16 [16%] P<0.0001). The colchicine group, compared to the standard group, had lesser pericardial drain output (186 ± 84 mL vs. 351 ± 83, P<0.001), shorter pericardial drain duration (16 ± 4 vs. 23 ± 19 hours, P<0.04), and similar incidence of delayed pericardial effusion (4 [1.6%] to 3 [3%], P = 0.42) when compared to the standard group. CONCLUSION: Use of colchicine periprocedurally was associated with significant reduction in postprocedural pericarditis and associated complications.

Cryoballoon pressure waveform change during balloon inflation is not a reliable predictor of adequate pulmonary vein occlusion.

BACKGROUND: Cryoballoon ablation of pulmonary veins (PVs) is widely used to treat atrial fibrillation (AF). Successful ablation requires occluding the PVs by cryoballoon. Angiography is a standard method of assessing PV occlusion. To decrease contrast doses and overcome potential contraindications (e.g., allergy to contrast, renal disease), alternative methods have been tested, including intracardiac echocardiography, transesophageal echocardiography-color flow Doppler, and distal cryoballoon pressure monitoring. OBJECTIVE: We evaluated pressure monitoring's accuracy in detecting PV occlusion during cryoballoon ablation. METHODS: We studied 72 PVs in 18 nonconsecutive patients (mean age 68 ± 8 years; 13 male) who underwent cryoballoon ablation for paroxysmal AF. In 67 PVs, we documented the point at which the recorded pressure waveform at the distal tip of the inflated cryoballoon transformed from a left atrial into a pulmonary arterial pressure waveform. PV occlusion was confirmed by concurrent PV angiography through the distal balloon channel. Occlusion was rated on a I­IV scale in which I indicated poor occlusion with major leakage and IV indicated complete occlusion without leakage. RESULTS: In 43 of 67 PVs (64%), the change in the pressure waveform from left atrial to pulmonary arterial was associated with complete PV occlusion (grade IV), confirmed by angiography. In the other 24 PVs, complete occlusion was achieved by further movement of the cryoballoon under intracardiac echocardiographic guidance and angiographic confirmation. All 67 PVs were electrically isolated with cryoballoon. CONCLUSIONS: The change in pressure waveforms at the distal tip of inflated cryoballoon is not a reliable predictor of complete PV occlusion during cryoballoon ablation.

Risk Stratification in Patients Who Underwent Percutaneous Left Atrial Appendage Occlusion.

Left atrial appendage occlusion (LAAO) is effective in preventing thromboembolism. Risk stratification tools could help identify patients at risk for early mortality after LAAO. In this study, we validated and recalibrated a clinical risk score (CRS) to predict risk of all-cause mortality after LAAO. This study used data from patients who underwent LAAO in a single-center, tertiary hospital. A previously developed CRS using 5 variables (age, body mass index [BMI], diabetes, heart failure, and estimated glomerular filtration rate) was applied to each patient to assess risk of all-cause mortality at 1 and 2 years. The CRS was recalibrated to the present study cohort and compared with established atrial fibrillation-specific (CHA2DS2-VASc and HAS-BLED) and generalized (Walter index) risk scores. Cox proportional hazard models were used to assess the risk of mortality and discrimination was assessed by Harrel C-index. Among 223 patients, the 1- and 2-year mortality rates were 6.7% and 11.2%, respectively. With the original CRS, only low BMI (<23 kg/m2) was a significant predictor of all-cause mortality (hazard ratio [HR] [95% CI] 2.76 [1.03 to 7.35]; p = 0.04). With recalibration, BMI <29 kg/m2 and estimated glomerular filtration rate <60 ml/min/1.73 m2 were significantly associated with an increased risk of death (HR [95% CI] 3.24 [1.29 to 8.13] and 2.48 [1.07 to 5.74], respectively), with a trend toward significance noted for history of heart failure (HR [95% CI] 2.13 [0.97 to 4.67], p = 0.06). Recalibration improved the discriminative ability of the CRS from 0.65 to 0.70 and significantly outperformed established risk scores (CHA2DS2-VASc = 0.58, HAS-BLED = 0.55, Walter index = 0.62). In this single-center, observational study, the recalibrated CRS accurately risk stratified patients who underwent LAAO and significantly outperformed established atrial fibrillation-specific and generalized risk scores. In conclusion, clinical risk scores should be considered as an adjunct to standard of care when evaluating a patient's candidacy for LAAO.

Incidence, Risk Score Performance, and In-Hospital Outcomes of Postoperative Atrial Fibrillation After Cardiac Surgery.

BACKGROUND: Postoperative atrial fibrillation (POAF) frequently complicates cardiac surgery. Predicting POAF can guide interventions to prevent its onset. This study assessed the incidence, risk factors, and related adverse outcomes of POAF after cardiac surgery. METHODS: A cohort of 1,606 patients undergoing cardiac surgery at a tertiary referral center was analyzed. Postoperative AF was defined based on the Society of Thoracic Surgeons' criteria: AF/atrial flutter after operating room exit that either lasted longer than 1 hour or required medical or procedural intervention. Risk factors for POAF were evaluated, and the performance of established risk scores (POAF, HATCH, COM-AF, CHA2DS2-VASc, and Society of Thoracic Surgeons risk scores) in predicting POAF was assessed using discrimination (area under the receiver operator characteristics curve) analysis. The association of POAF with secondary outcomes, including length of hospital stay, ventilator time, and discharge to rehabilitation facilities, was evaluated using adjusted linear and logistic regression models. RESULTS: The incidence of POAF was 32.2% (n = 517). Patients who developed POAF were older, had traditional cardiovascular risk factors and higher Society of Thoracic Surgeons risk scores, and often underwent valve surgery. The POAF risk score demonstrated the highest area under the receiver operator characteristics curve (0.65), but risk scores generally underperformed. Postoperative AF was associated with extended hospital stays, longer ventilator use, and higher likelihood of discharge to rehabilitation facilities (odds ratio, 2.30; 95% CI, 1.73-3.08). CONCLUSION: This study observed a high incidence of POAF following cardiac surgery and its association with increased morbidity and resource utilization. Accurate POAF prediction remains elusive, emphasizing the need for better risk-prediction methods and tailored interventions to diminish the effect of POAF on patient outcomes.

Implantation success and infection in cardiovascular implantable electronic device procedures utilizing an antibacterial envelope.

BACKGROUND: Cardiovascular implantable electronic device (CIED) infection rates are increasing faster than implantation rates. More effective antimicrobial prophylaxis may help reduce CIED infections and improve clinical outcomes. The AIGIS(Rx)(®) antibacterial envelope is a polymer mesh implanted in the generator pocket with the CIED. After implantation it releases two antibiotics, minocycline and rifampin, that have been shown to reduce infections associated with other medical devices. The purpose of this retrospective cohort study is to determine the rate of CIED implantation success and CIED infection in procedures utilizing the antibacterial envelope. METHODS: This study enrolled consecutive CIED procedures utilizing the antibacterial envelope at 10 US academic, community, and Veterans Affairs medical centers. Procedures following an explantation for a prior CIED infection or off-label use of the antibacterial envelope were excluded. RESULTS: The 624 eligible procedures (age 70 ± 13 years, 68.1% men, 27.2% renal insufficiency, 35.4% oral anticoagulant use, 67.8% replacement/revision procedures) utilized pacemakers (35%), implantable cardioverter-defibrillators (ICD)(29%), and cardiac resynchronization therapy with defibrillator devices (CRT-D)(36%). Nearly half of the patients (49%) had at least three predefined risk factors for CIED infection. CIED implantation was successful in 621 procedures (99.5%[95% confidence interval (CI) 98.8-99.9]). There were three major infections (0.48%[95%CI 0.17-1.40]) after 1.9 ± 2.4 months follow-up. The infections followed one ICD revision and two CRT-D replacements. There were seven deaths; none was a result of the antibacterial envelope or the CIED procedure. CONCLUSIONS: CIED procedures that utilized an antibacterial envelope had a high rate of CIED implantation success (>99%). Although the follow-up to date is short, there was also a low rate of infection (<0.50%) in this population at high risk for CIED infection.

Contact-force recovery predicts the absence of cardiac perforation during steam pops.

PURPOSE: Cardiac perforation (CP) is an uncommon but clinically important complication of radiofrequency ablation (RFA). We previously showed that contact-force recovery after a steam pop predicts the absence of CP in an open-chest animal model after pericardial dissection. We attempted to determine whether this also applies when pericardium is present. METHODS: In 5 open-chest sheep, left atrial RFA was performed under direct observation with a 7.5F ThermoCool SmartTouch force-sensing catheter (Biosense Webster Inc., Irvine, CA, USA). The catheter's contact force was measured every 50 ms during RFA. After each steam pop, the presence (+) or absence (-) of CP was noted, as well as whether pericardium was present over the ablation site. Contact-force signals were analyzed to detect contact-force recovery. Perforation rates were compared between sites with or without pericardium. RESULTS: Ninety-six steam pops occurred: 77 with pericardium and 19 without. For the pericardial steam pops, contact-force recovery occurred in 31/60 CP- events (52%) and 1/17 CP+ events (6%; P = 0.0006). For nonpericardial steam pops, contact-force recovery occurred in 4/9 CP- events (44%) and 1/10 CP+ events (P = 0.14). The rate of CP was 22% with pericardium and 52% without (P = 0.02). Pericardial tissue charred extensively during steam pop induction, even in the absence of CP. CONCLUSIONS: Contact-force recovery predicts the absence of CP during RFA independently of whether the pericardium is present. The presence of the pericardium may decrease the likelihood of perforation, perhaps by acting as a thermal sink. Additional studies are needed to correlate these results with clinical experience.

Cardiac resynchronization therapy in patients with right ventricular pacing-induced cardiomyopathy.

BACKGROUND: It is not known whether patients with normal baseline left ventricular (LV) function who develop right ventricular (RV) pacing-induced cardiomyopathy as a result of dual-chamber pacing can benefit from cardiac resynchronization therapy (CRT). We retrospectively assessed the effect of a CRT upgrade on RV pacing-induced cardiomyopathy. METHODS AND RESULTS: We reviewed the charts of patients who received a CRT device for RV pacing-induced cardiomyopathy. We assessed the effects of CRT on LV function, recovery, and other response parameters. From September 2005 through February 2009, 21 patients (13 men; aged 63 + or - 9 years) underwent a treatment upgrade to a CRT system. Before the dual-chamber pacemaker was implanted, the LV ejection fraction (LVEF) was 53 + or - 2.3%. After pacing, the LVEF was 31.2 + or - 3.8%, the LV end-diastolic dimension (LVEDD) was 5.8 + or - 0.5 cm, and B-type natriuretic peptide (BNP) levels were 426 + or - 149 pg/mL. The duration of pacing before documentation of pacing-induced cardiomyopathy was 3.8 + or - 1.5 months. All the patients had been on a stable medical regimen for at least 2 months. After the upgrade to CRT, the follow-up time was 4.9 + or - 0.9 months. Sixteen patients (76%) reported a significant improvement in their symptoms. After the CRT upgrade, the LVEF increased to 37.4 + or - 9.0% (P < 0.01 vs pre-CRT). The LVEDD decreased to 5.0 + or - 1.0 cm (P = 0.03 vs pre-CRT), and BNP levels decreased to 139 + or - 92 pg/mL (P = 0.08 vs pre-CRT). CONCLUSION: A CRT upgrade is an effective treatment for RV pacing-induced cardiomyopathy and should be implemented as soon as the diagnosis is established. Unfortunately, about 24% of our patients did not respond to the upgrade.

Variability in postpacing intervals predicts global ventricular activation pattern during tachycardia.

INTRODUCTION: Assessment of ventricular activation pattern is critical to the successful ablation of ventricular tachycardia (VT). We have previously shown that the global atrial activation pattern during tachycardia can be rapidly and accurately assessed by calculating the postpacing interval variability (PPIV); PPIV was minimal in circuitous tachycardias and highly variable in centrifugal tachycardias. In the present study, we use the PPIV to determine the ventricular global activation pattern during VT. METHODS: Patients with mappable VT were included. We defined global ventricular activation as either centrifugal (arising from a focus with radial expansion) or circuitous (gross macro-reentrant circuit), based on the findings of electroanatomic mapping. PPIV was calculated as the difference in postpacing interval with right ventricular apical overdrive pacing during tachycardia at cycle lengths (CL) 10 ms and 30-ms shorter than tachycardia, regardless of the origin of the tachycardia. We studied 20 patients with 23 VTs (11 centrifugal, mean CL 390 +/- 36.1 ms; 12 circuitous, mean CL 418 +/- 75.7 ms). RESULTS: The mean PPIV was 45 +/- 16 ms for patients with centrifugal VT and 6.7 +/- 4.1 ms for patients with circuitous VT. Rank sum analysis of PPIV showed a significant difference between the two groups (P < 0.05). CONCLUSIONS: Our data suggest that the global ventricular activation pattern during VT can be rapidly and accurately defined by assessing the PPIV. This technique allows for a rapid confirmation of the tachycardia activation and significantly facilitates mapping and ablation.

Thromboembolism in Atrial Fibrillation: Role of the Left Atrial Appendage.

Atrial fibrillation (AF) is the most common arrhythmia. Patients with AF have a higher risk for thromboembolism than individuals without AF. The left atrial appendage (LAA) is the main source of thromboembolism because of its anatomic, mechanical, and electrophysiologic properties, and accounts for more than 90% of thrombus formation in patients with AF. Advancement in imaging expands knowledge about anatomic and physiologic characteristics of LAA. The risk of thromboembolism events in patients with AF depends on clinical comorbidities and structural and physiologic parameters of atria, especially LAA. This article discusses AF-related thromboembolic events and the role of the LAA.

Exclusion of electrical and mechanical function of the left atrial appendage in patients with persistent atrial fibrillation: differences in efficacy and safety between endocardial ablation vs epicardial LARIAT ligation (the EXCLUDE LAA study).

BACKGROUND: Electrical isolation of the left atrial appendage (LAA) may provide incremental benefits for arrhythmia management in patients undergoing radiofrequency ablation (RFA) for persistent atrial fibrillation (AF). OBJECTIVE: The aim of this study was to compare efficacy and safety of endocardial ablation and LAA exclusion with LARIAT device for electrical and mechanical exclusion of LAA. METHODS: We compared patients who underwent endocardial LAA isolation during index RFA for persistent AF and underwent a repeat RFA to patients who underwent LAA exclusion with LARIAT device followed by RFA for AF in this multicenter registry. Efficacy of electrical and mechanical isolation of LAA was assessed. RESULTS: We included 182 patients of which 91 patients underwent endocardial LAA isolation during RFA for AF, and 91 patients underwent LAA exclusion with LARIAT device followed by RFA for AF. Baseline characteristics were similar except for higher CHA2DS2-VASc score, coronary artery disease, and prior stroke rate in LARIAT arm. Persistence of electrical isolation (measured at beginning of second procedure) after LARIAT procedure was higher than one-time AF-RFA (96.7% vs 52.8%, p < 0.01). Acute pulmonary vein isolation rates were similar in both arms. AF recurrence rate after second isolation attempts at 1 year was similar in both arms. No difference in major complications was noted between both arms. CONCLUSIONS: LAA exclusion with LARIAT device appears to be more efficacious as compared to one-time endocardial ablation, but not compared to repeat isolation, in achieving complete electrical isolation of LAA for persistent AF.

Cardiac resynchronization therapy may improve symptoms of congestive heart failure in patients without electrical or mechanical dyssynchrony.

AIMS: Cardiac resynchronization therapy (CRT) has reportedly not been effective in the absence of electrical or mechanical dyssynchrony. We present six patients with severe left ventricular (LV) dilation, mitral regurgitation (MR), and non-ischaemic cardiomyopathy who underwent CRT. We assessed the effects of CRT on LV ejection fraction (EF), LV dimensions, mitral valve regurgitant fraction (RF), pulmonary arterial pressures (PAP), and serum levels of B-natriuretic peptide (BNP). METHODS AND RESULTS: All patients had severe LV dilation (>/=6.8 cm) and no electrical or mechanical dyssynchrony. All patients underwent CRT-D (with defibrillator) without complications. Average echocardiographic follow-up was 4.6 months. Mean LVEF increased significantly from 20.8 +/- 3.4 to 28.3 +/- 2.9% after CRT (P < 0.01). Mean LV end-diastolic dimension decreased significantly from 6.9 +/- 0.15 to 6.45 +/- 0.33 cm after CRT (P = 0.03); mean BNP serum level decreased from 1738 +/- 526 to 1040 +/- 768 pg/mL (P = 0.07). Baseline RF decreased from 45 +/- 12.2 to 20 +/- 10.9% after CRT-D (P = 0.009). Mean PAP decreased from 48.5 +/- 5.8 to 42.6 +/- 5.2 (P = 0.03). In five patients, New York Heart Association class symptoms improved by at least one level. No patients required assist devices or transplantation. One patient was hospitalized during follow-up. CONCLUSION: We describe six patients with severe LV dilation without evidence of electrical or mechanical dyssynchrony who improved with CRT, possibly due to improvement in MR.

Variability in post-pacing intervals predicts global atrial activation pattern during tachycardia.

INTRODUCTION: Knowledge of the global atrial activation pattern is critical to ablation of an atrial arrhythmia. We hypothesized that the variability in post-pacing intervals (PPIs) with pacing at different cycle lengths (CLs) from the same pacing site, regardless of distance to the circuit, can be used to identify atrial activation patterns during tachycardia. METHODS AND RESULTS: Consecutive patients referred for ablation of organized atrial arrhythmias were included (n = 28, 31 total tachycardias). The variability in PPIs (PPIV) was calculated by comparing the difference in PPIs after overdrive pacing with 5-second trains 10, 20, and 30 ms shorter than the tachycardia cycle length (TCL). The global activation pattern was defined as circuitous (macroreentrant atrial circuit) or centrifugal (focal origin with centrifugal radiation) by electroanatomic mapping. Except for one case, all pacing was performed from the proximal coronary sinus bipole. Circuitous tachycardias (n = 17, all macro-reentrant) exhibited minimal variability with pacing at 10 ms and 30 ms shorter than TCL (6.0 +/- 2.5 ms), whereas centrifugal tachycardias (n = 14, 8 microreentrant) displayed a high degree of variability (56.5 +/- 20.6 ms). Rank sum analysis of PPIV suggests that the two groups are indeed distinct (P < 0.001). Using PPIV cutoffs of or=30 ms, circuitous and centrifugal activation patterns could be distinguished with a high degree of sensitivity (94% circuitous, 92.8% centrifugal) and 100% specificity. CONCLUSIONS: Our data support the use of PPIV to rapidly and accurately predict the global activation pattern during atrial arrhythmia.