Abstract Background/Introduction Q-FFICIENCY evaluated 12-month (M) safety and efficacy of temperature-controlled paroxysmal atrial fibrillation ablation with a novel contact force-sensing, radiofrequency catheter with 3 microelectrodes and 6 thermocouples. Patients underwent pulmonary vein isolation with very high-power short-duration (vHPSD; 90 W/ up to 4 s) mode in combination with conventional-power temperature-controlled (CPTC; 25–50 W) mode. Purpose To assess procedural efficiency, safety, and 12M outcomes of participants ablated under near-zero fluoroscopy guidance compared to procedures performed with standard fluoroscopy. Methods In this US multi-centre (22 sites), non-randomised investigational study, patients underwent pulmonary vein isolation with vHPSD as primary ablation mode; CPTC was used for PV touch-up or non-PV ablation. Primary safety endpoint was incidence of primary adverse events ≤7 days post-procedure. Primary effectiveness was freedom from documented atrial tachyarrhythmia recurrence and additional pre-defined failure modes (acute failure, repeat ablation, new/higher dose anti-arrhythmic drug). Participants were followed-up through 12M post-ablation (3M blanking & 9M evaluation) to assess safety, effectiveness, and healthcare utilisation. Results Of 191 participants enrolled (63.5±10.7 years, CHA2DS2-VASc 2.4±1.5, 60.7% men), 166 were ablated with the investigational catheter, and 165 had fluoroscopy data available for inclusion in this analysis. Forty-four participants received ≤1 minute of fluoroscopy. Compared to the >1-minute of fluoroscopy cohort, the ≤1-minute group showed improved efficiencies in all procedural parameters (Table). Primary adverse event rates were similar among groups (≤1-minute, 4.5%; >1-minute, 3.3%). Kaplan-Meier estimated 12M clinical success rates (i.e., freedom from documented symptomatic recurrence) were similar regardless of fluoroscopy exposure (≤1-minute, 85.4%; >1-minute, 86.0%). Freedom from cardiovascular hospitalisation 12M post-ablation was comparable among groups (90.8% vs 88.0%). Conclusion Near-zero fluoroscopy paroxysmal atrial fibrillation ablation with the novel temperature-controlled catheter in vHPSD mode, alone or combined with CPTC, led to enhanced procedural efficiencies with good effectiveness and clinical success without comprising safety. Funding Acknowledgement Type of funding sources: Private company. Main funding source(s): Biosense Webster, Inc.

BACKGROUND Pure left bundle branch (LBB) capture should result in typical RBBB (rsR’) morphology. However, numerous paced QRS morphologies are observed during LBB area pacing (LBBAP). There are limited papers describing the various electrocardiographic (ECG) morphologies seen with LBBAP. Objective: To evaluate the various ECG characteristics encountered in LBBAP. METHODS AND RESULTS Patients referred for pacemaker implantation between 08/2019-01/2021 were considered for LBBAP. LBBAP was performed by implantation of a Medtronic 3830 lead 2 cms distal to His and confirmed by previously published criteria. Paced QRS morphology and QRS axis was analyzed. Baseline, ECG, and implantation characteristics are summarized in table 1. Of 264 LBBAP ECGs, the most common morphology seen during unipolar tip pacing was an incomplete RBBB pattern (qR) in V1 in 165 (69.9%) patients. rSR’ pattern was seen in 9 (3.2%) and a narrow QS pattern in 60 (21.5%) patients. CONCLUSION Various ECG morphologies may be encountered during successful LBB area capture and are associated with similar QRSd, pacing characteristics and short-term lead performance. These morphologies are due to capture of various structures (RV or LV septum, capture of LBB, LPF +/- RBB) and are likely due to virtual-electrode effect. Pure left bundle branch (LBB) capture should result in typical RBBB (rsR’) morphology. However, numerous paced QRS morphologies are observed during LBB area pacing (LBBAP). There are limited papers describing the various electrocardiographic (ECG) morphologies seen with LBBAP. Objective: To evaluate the various ECG characteristics encountered in LBBAP. Patients referred for pacemaker implantation between 08/2019-01/2021 were considered for LBBAP. LBBAP was performed by implantation of a Medtronic 3830 lead 2 cms distal to His and confirmed by previously published criteria. Paced QRS morphology and QRS axis was analyzed. Baseline, ECG, and implantation characteristics are summarized in table 1. Of 264 LBBAP ECGs, the most common morphology seen during unipolar tip pacing was an incomplete RBBB pattern (qR) in V1 in 165 (69.9%) patients. rSR’ pattern was seen in 9 (3.2%) and a narrow QS pattern in 60 (21.5%) patients. Various ECG morphologies may be encountered during successful LBB area capture and are associated with similar QRSd, pacing characteristics and short-term lead performance. These morphologies are due to capture of various structures (RV or LV septum, capture of LBB, LPF +/- RBB) and are likely due to virtual-electrode effect.

Result : A total of 94 patients with the native QRS duration of 167.2±17.2 ms were included. In 92 patients, iLCSP was achieved and demonstrated RBBB pattern with the paced QRS duration of 116.4±12.6ms (Figure 1B, middle panel). Fusion of iLCSP and native conduction via the RBB eliminated RBBB and resulted in an average QRS duration of 103.2±10.1 ms (Figure 1C). In a subgroup that underwent a two-lead implantation technique (n=21), a Purkinje pre-potential was recorded during His corrective pacing from the intraseptal lead (Figure 1B, right panel). Output dependent selective and non-selective iLCSP were demonstrated in 52% patients, with the same stimulus to peak left ventricular activation time of 82ms (Figure 1B, left and middle panel). Lead parameters remained stable at 1-year (threshold 0.61±0.17V/0.5ms, R wave 13±5.8mV, Figure 1D, E). During follow-up, only one patient had an increase in LBB capture threshold to 2.5V/0.5ms and there were no other complications such as dislodgment, infections, embolism or stroke associated with the implantation.

Abstract Background His bundle pacing (HBP) has been shown to correct left bundle branch block (LBBB), however it often requires high pacing output and the success rate is variable. Objective To assess the feasibility and safety of left bundle branch area pacing (LBBAP) in patients with LBBB. Methods From Apr 2014 to Aug 2018, patients with LBBB from multicenters indicated for CRT or pacing therapy were included. LBBAP was performed by advancing the MDT 3830 lead deep into the septum about 1 cm distal to the His bundle region (Figure 1F). Pacing characteristics, success rate, threshold and R-wave amplitude were assessed. Results A total of 94 patients aged 68.3±10.7 y with the native QRS duration of 167.2±17.2 ms were included. In 92 patients, LBBAP was successfully achieved and demonstrated RBBB pattern during unipolar tip pacing (UTP), with the paced QRS duration of 116.4±12.6ms (Figure 1C). Fusion of LBBAP and native conduction via the RBB eliminated RBBB and resulted in an average QRS duration of 103.2±10.1 ms (Figure 1D). LBB potential could be recorded from the LBB lead during correction of LBBB by HBP in 21 patients who used two leads method (His lead and LBB lead, Figure 1B). Output dependent selective and non-selective LBBAP were demonstrated in 48 patients (Figure 1C, D). The LBB capture threshold by UTP was 0.53±0.18V/0.5ms at acute and 0.62±0.17V/0.5ms at 6 months and 0.65±0.2V/0.5ms at 1 year. The R-wave amplitude were 11.4±5.2mV, 12.4±5.8mV and 12.0±5.8mV at acute, 6 month and 1 year. During follow-up, only one patient had an increase in LBB capture threshold to 2.5V/0.5ms at 3 months and there were no other complications such as dislodgment, infections, embolism or stroke associated with the implantation. Conclusion Permanent LBBAP is feasible and safe in patients with LBBB.

Atrial fibrillation (AF) is the most common arrhythmia in the United States, with ≈7 million Americans estimated to have AF by 2020.1,2 A major cause of morbidity and mortality in AF is stroke. Pharmacological therapy for the prevention of stroke has undergone a renaissance with the advent of newer oral anticoagulants that are safe and effective alternatives to warfarin. However, the decision to initiate anticoagulation remains a subjective assessment of risks versus benefits. Although guided by well-validated risk scores for stroke and bleeding,3–5 real-world decisions on anticoagulation continue to differ significantly from guideline recommendations, with many patients at high risk not receiving anticoagulation because of a perceived high risk of bleeding and many low-risk patients being anticoagulated as a result of a perceived low risk of bleeding, the so-called risk-treatment paradox.6 This phenomenon, thought to account for the continued underuse of oral anticoagulation therapy,7 has yet to be validated in a large outpatient-based practice. Therefore, the present study by Steinberg et al8 in this issue of Circulation is a timely effort to better understand and address some of the reasons underlying this risk mismatch in thromboembolic assessment and anticoagulation therapy in a community outpatient-based group of patients with stable AF.Article see p 2005The authors examined 10 094 AF patients enrolled in the Outcomes Registry for Better Informed Treatment of Atrial Fibrillation (ORBIT-AF) between June 2010 and August 2011.9 This US prospective registry of incident and prevalent AF is formed by a multispecialty collaboration of healthcare providers, including primary care physicians, cardiologists, and electrophysiologists. It is the largest clinical registry of its kind in the United States, enrolling ≈10 000 patients from 200 US outpatient practices. The patients are followed up for at least 2 years to characterize real-world …

Normal LV contraction is dependent on a specific organized circumferential and longitudinal fiber contraction.1 RV apical pacing disrupts normal electrical activation, resulting in LV dyssynchrony and inefficient cardiac pump function.2-5 There is clinical evidence that a high percentage of RV pacing is deleterious to cardiac function.6,7 Despite extensive clinical and animal data showing the deleterious hemodynamic effects of chronic RV pacing, there are limited and mostly retrospective data studying the longterm effects of RV pacing in pacemaker-dependent patients. Furthermore, animal models of nontachycardia chronic RV pacing have failed to reproduce LV systolic dysfunction and/or heart failure (HF) after 6 months of pacing.8,9 Clinical data support the use of cardiac resynchronization therapy (CRT) in pacemaker-dependent subjects with cardiomyopathy in an attempt to minimize LV dyssynchrony and prevent further deterioration or even reverse LV dysfunction and HF symptoms.10-15 However, clinical response to CRT upgrade in pacemaker-dependent subjects with potential RV-pacinginduced cardiomyopathy has not been widely studied. In the present issue of the Journal, Adelstein and collaborators16 perform a retrospective analysis of their experience at the University of Pittsburgh to describe the incidence of hyperresponse to CRT upgrade in adult pacemaker-dependent patients with nonischemic cardiomyopathy and severe HF symptoms and propose clinical characteristics that may predict CRT hyperresponse in this population.16

Downloaded from ClinicalKey.com at Florida Atlantic Univers For personal use only. No other uses without permission. Copy fter cryoablation inside the vein, all patients had documented PV DB and were in normal sinus rhythm at the end of the procedure. he average PV diameter before and after the procedure was nchanged (1.77 0.18 vs 1.74 0.19, P .641). The average uoroscopic and procedure times were 57 16 min and 5.3 1.2 ours, respectively. At 1-year follow-up, 75% of patients remained n sinus rhythm off antiarrhythmic medication; 7 of 9 patients ndergoing a repeat procedure were in sinus rhythm at 1 year off ntiarrhythmics. None of the patients had clinical evidence of PV tenosis after cryoablation.

Introduction: The objective of this study was to test whether the temporal patterns of ventricular tachyarrhythmia recurrences in patients with implantable cardioverter‐defibrillator (ICD) follow a random or a clustered distribution. Methods: Data analysis was conducted using the Medtronic (Minneapolis, MN) Gem DR database of 521 ICD patients. Patients with ≥3 sustained ventricular tachyarrhythmia detections that resulted in shock or antitachycardia pacing therapies were studied. The times between consecutively treated ICD detections for each patient were compared to an exponential model of random recurrences and a Weibull model for clustered recurrences. Results: Seventy‐one patients had ≥ 3VT episodes during follow‐up of 131 ± 86 days. A total of 2347 VT episodes were recorded (33 ± 65 episodes/patient, median 10 episodes/patient). Patient age was 66 ± 13 years, 78% male, 83% coronary artery disease, ejection fraction 31 ± 11%, and 63% were taking antiarrhythmic drugs. By the Kolmogorov‐Smirnov goodness‐of‐fit test, 38 of 71 patients (53.5%) showed that the pattern of detections differed from an exponential model (P < 0.01 for each patient and the proportion of patients was similar to chance at P = 0.65). In contrast, only 11 out of 71 patients (15.5%) showed that the pattern differed from the Weibull model (P < 0.01 for each patient). The proportion of patients fitting the Weibull model was significantly greater than chance and was greater that the proportion fitting the exponential model (both P < 0.001). The time interval between consecutive detections was less than 1 hour for 78% of all 2347 detections. The proportion of all 521 patients with ≥2, ≥3, ≥ 4, ≥6, ≥8, and ≥10 ICD detections in a 24‐hour period was 10.5%, 9.5%, 8.1%, 7.0%, 6.3%, and 5.2%, respectively. Conclusion: In most patients with ≥3 ICD detections, the recurrence pattern of treated ventricular tachyarrhythmia detections are clustered and can be described by a Weibull distribution. The proportion of patients with multiple detections in a 24‐hour period declines in a linear fashion as the number of events in 24 hours increases from 2 to 10 events.

Introduction: Isolation of all pulmonary veins (PV) is advocated for treatment of paroxysmal atrial fibrillation (PAF). However, the superior PVs are responsible for most AF triggers, whereas the inferior PVs carry the higher risk for ablation‐induced ostial stenosis. The aim of this study was to compare a superior PV isolation approach with isolation of all PVs for treatment of PAF. Methods and Results: Fifty‐two patients with PAF were randomized to either left superior pulmonary vein (LSPV) isolation followed by additional isolation of the right superior pulmonary vein (RSPV) in case of AF recurrence (group A, n = 27) or isolation of all four PVs followed by a repeat procedure in case of recurrence (group B, n = 25). At 1‐year follow‐up, 11 patients (41%) in group A and 8 patients (32%) in group B had AF relapse (P = 0.55). No significant differences in AF relapse were detected between groups at 3 and 12 months (log rank = 0.36, P = 0.54) and by Cox proportional hazards model analysis (P = 0.62). Nonsignificant PV stenosis was detected in two patients from group B. Total radiofrequency energy delivery and fluoroscopy and procedure times were lower in group A: 8.9 ± 1.4 minutes vs 25.6 ± 3.7 minutes (P < 0.001), 22.2 ± 6.8 minutes vs 62 ± 10.3 minutes (P < 0.001), and 131.8 ± 26.5 minutes vs 222.2 ± 32.3 minutes (P < 0.001), respectively. Conclusion. A staged superior PVs isolation approach confers equal success rates but with reduced radiofrequency energy delivery and fluoroscopy and procedure times compared to isolation of all PVs at the initial ablation attempt. (J Cardiovasc Electrophysiol, Vol. 15, pp. 1‐5, June 2004)

Introduction: This study examined the relationship between dobutamine facilitation of ventricular tachyarrhythmia (VT) inducibility with programmed electrical stimulation (PES) and dobutamine stress‐induced myocardial ischemia.

BACKGROUND:One of the perceived benefits of dual-chamber implantable cardioverter-defibrillators (ICDs) is the reduction in inappropriate therapy due to new detection algorithms. It was the purpose of the present investigation to propose methods to minimize bias during such comparisons and to report the arrhythmia detection clinical results of the PR Logic dual-chamber detection algorithm in the GEM DR ICD in the context of these methods.METHODS AND RESULTS:Between November 1997 and October 1998, 933 patients received the GEM DR ICD in this prospective multicenter study. A total of 4856 sustained arrhythmia episodes (n=311) with stored electrogram and marker channel were classified by the investigators; 3488 episodes (n=232) were ventricular tachycardia (VT)/ventricular fibrillation (VF), and 1368 episodes (n=149) were supraventricular tachycardia (SVT). The overall detection results were corrected for multiple episodes within a patient with the generalized estimating equations (GEE) method with an exchangeable correlation structure between episodes. The relative sensitivity for detection of sustained VT and/or VF was 100.0% (3488 of 3488, n=232; 95% CI 98.3% to 100%), the VT/VF positive predictivity was 88.4% uncorrected (3488 of 3945, n=278) and 78.1% corrected (95% CI 73.3% to 82.3%) with the GEE method, and the SVT positive predictivity was 100.0% (911 of 911, n=101; 95% CI 96% to 100%).CONCLUSIONS:A structured approach to analysis limits the bias inherent in the evaluation of tachycardia discrimination algorithms through the use of relative VT/VF sensitivity, VT/VF positive predictivity, and SVT positive predictivity along with corrections for multiple tachycardia episodes in a single patient.

BACKGROUND:More than 200,000 permanent pacemakers will be implanted in the United States in 2000 at a cost of more than $2 billion. Sick sinus syndrome (SSS) will likely account for approximately half of all cases necessitating implantation. Pacemaker technology permits the selection of ventricular (single-chamber) or dual-chamber devices. However, clinical and outcomes data are inadequate to support a clear recommendation that one or the other type of device be used.METHODS:The Mode Selection Trial (MOST) is a single-blind study supported by the National Heart, Lung, and Blood Institute designed to enroll 2000 patients with SSS. All patients will receive a DDDR pacemaker programmed to VVIR or DDDR before implantation. The average time of follow-up will be 3 years. MOST has a >90% power to detect a 25% reduction in the primary end point-nonfatal stroke or total (all cause) mortality-in the DDDR-treated group. Secondary end points will include health-related quality of life and cost effectiveness, atrial fibrillation, and development of pacemaker syndrome. Prespecified subgroups for analysis will include women and the elderly. Enrollment was completed in October 1999, with a total of 2010 patients.RESULTS:The median age of the first 1000 enrolled patients is 74 years, with 25% of patients 80 years or older. Women comprise 49%, and 17% are nonwhite, predominantly black (13%). Before pacemaker implantation, 22% of patients reported a history of congestive heart failure, 11% coronary angioplasty, and 25% coronary bypass surgery. Supraventricular tachycardia including atrial fibrillation was present in 53% of patients. A prior stroke was reported by 12%. Antiarrhythmic therapy was in use in 18% of patients.CONCLUSIONS:MOST will fill the clinical need for carefully designed prospective studies to define the benefits of dual-chamber versus single-chamber ventricular pacing in patients with SSS. The MOST population is typical of the overall pacemaker population in the United States. Thus the final results of MOST should be clinically generalizable.

Increased attention is now being focused on developing new technologies to cure atrial fibrillation using catheter ablation techniques. The performance of a MAZE-type procedure using standard catheter ablation technologies is arduous and is associated with an unacceptable risk of complications. The Guidant Heart Rhythm Technologies Linear Ablation System was developed to create long transmural linear lesions. Unique features of this system include the availability of different preshaped multi-electrode steerable ablation catheters, the use of phased radiofrequency (RF) energy, and the control of RF output by varying the duty cycle. A prospective multicenter clinical trial to evaluate the safety and efficacy of a right atrial ablation procedure using this technology to treat atrial fibrillation is currently underway. To date, 15 patients have been enrolled and the procedure was acutely effective in 14 of 15 patients with no complications. Atrial fibrillation has recurred during short-term follow-up in 12 of 15 patients, a not surprising result, because this initial phase of testing involved only right-sided ablation. The early results of the phase I clinical trial confirm the findings of others that successful ablation of chronic atrial fibrillation is likely to require a left atrial approach. This clinical trial, as well as others that are currently underway, will be invaluable in the continuing development of catheter ablation of atrial fibrillation and, ultimately, in determining if the routine use of this therapeutic tool can become a reality.

Background-In a multicenter, double-blind, placebo-controlled study, the long-term effects of amiodarone on morbidity and mortality in patients with congestive heart failure (CHF) and atrial fibrillation (AF) were evaluated during a 4-year period.Methods and Results-Of 667 patients with CHF, 103 (15%) had AF at baseline, Of these, 51 were randomized to amiodarone and 52 to placebo. The group with sinus rhythm and the group in AF were comparable except for a higher proportion of AF in patients with nonischemic versus ischemic cardiomyopathy (41% versus 27%, P<0.005). The mean ventricular response (VR) during AF over 24 hours was reduced by amiodarone at 2 weeks (20%, P=0.001), at 6 months (18%, P=0.001), and at 12 months (16%, P=0.006). Maximal VR was reduced 22% (P=0.001) at 2 weeks, 19% (P=0.001) at 6 months, and 14% (P=0.001) at 12 months. Sixteen of 51 patients on amiodarone and 4 of 52 on placebo converted to sinus rhythm during the study ((chi(2)=9.23, P=0.002). During follow-up, 11 of 268 patients in sinus rhythm on amiodarone at baseline and 22 of the 263 in sinus rhythm on placebo developed AF; the difference was significant (chi(2)=12.88, P=0.005). Analysis of total mortality during follow-up showed a significantly lower mortality rate (P=0.04) in patients in AF at baseline who subsequently converted to sinus rhythm on amiodarone than in those who did not convert to sinus rhythm on the drug.Conclusions-In patients with CHF, amiodarone has a significant potential to spontaneously convert patients in AF to sinus rhythm, with patients who convert having a lower mortality rate than those who do not. The drug prevented the development of new-onset AF and significantly reduced the VR in those with persistent AF.

Heart rate (HR) variability immediately prior to the onset of a spontaneous ventricular tachycardia or ventricular fibrillation (VT/VF) may be higher. Power spectral estimation using periodogram technique was performed on HR obtained from 135 sets of 1000 RR intervals that preceded spontaneous onset of VT/VF and 125 control sets. Ten frequency bands, each of 0.1 Hz bandwidth were analyzed. Time course analysis of spectral power was also performed at 7 non-overlapping segments of 100 samples (50 seconds) each prior to time of onset of VT/VF (ONSET) and on control data sets. The RR interval rhythms associated with ONSET had higher power in all spectral bands compared to the control group (p<0.01). It was also found that spectral power increased suddenly in the 50 seconds before ONSET. A HR spectral analysis may be useful in predicting the ONSET.