Arrhythmic Risk in Biventricular Pacing Compared With Left Bundle Branch Area Pacing: Results From the I-CLAS Study

BACKGROUND

Left bundle branch area pacing (LBBAP) may be associated with greater improvement in left ventricular ejection fraction and reduction in death or heart failure hospitalization compared with biventricular pacing (BVP) in patients requiring cardiac resynchronization therapy. We sought to compare the occurrence of sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) and new-onset atrial fibrillation (AF) in patients undergoing BVP and LBBAP.

METHODS

The I-CLAS study (International Collaborative LBBAP Study) included patients with left ventricular ejection fraction ≤35% who underwent BVP or LBBAP for cardiac resynchronization therapy between January 2018 and June 2022 at 15 centers. We performed propensity score-matched analysis of LBBAP and BVP in a 1:1 ratio. We assessed the incidence of VT/VF and new-onset AF among patients with no history of AF. Time to sustained VT/VF and time to new-onset AF was analyzed using the Cox proportional hazards survival model.

RESULTS

Among 1778 patients undergoing cardiac resynchronization therapy (BVP, 981; LBBAP, 797), there were 1414 propensity score-matched patients (propensity score-matched BVP, 707; propensity score-matched LBBAP, 707). The occurrence of VT/VF was significantly lower with LBBAP compared with BVP (4.2% versus 9.3%; hazard ratio, 0.46 [95% CI, 0.29-0.74]; P<0.001). The incidence of VT storm (>3 episodes in 24 hours) was also significantly lower with LBBAP compared with BVP (0.8% versus 2.5%; P=0.013). Among 299 patients with cardiac resynchronization therapy pacemakers (BVP, 111; LBBAP, 188), VT/VF occurred in 8 patients in the BVP group versus none in the LBBAP group (7.2% versus 0%; P<0.001). In 1194 patients with no history of VT/VF or antiarrhythmic therapy (BVP, 591; LBBAP, 603), the occurrence of VT/VF was significantly lower with LBBAP than with BVP (3.2% versus 7.3%; hazard ratio, 0.46 [95% CI, 0.26-0.81]; P=0.007). Among patients with no history of AF (n=890), the occurrence of new-onset AF >30 s was significantly lower with LBBAP than with BVP (2.8% versus 6.6%; hazard ratio, 0.34 [95% CI, 0.16-0.73]; P=0.008). The incidence of AF lasting >24 hours was also significantly lower with LBBAP than with BVP (0.7% versus 2.9%; P=0.015).

CONCLUSIONS

LBBAP was associated with a lower incidence of sustained VT/VF and new-onset AF compared with BVP. This difference remained significant after adjustment for differences in baseline characteristics between patients with BVP and LBBAP. Physiological resynchronization by LBBAP may be associated with lower risk of arrhythmias compared with BVP.

High-power short-duration versus low-power long-duration ablation for pulmonary vein isolation: A substudy of the AWARE randomized controlled trial

INTRODUCTION

Pulmonary vein isolations (PVI) are being performed using a high-power, short-duration (HPSD) strategy. The purpose of this study was to compare the clinical efficacy and safety outcomes of an HPSD versus low-power, long-duration (LPLD) approach to PVI in patients with paroxysmal atrial fibrillation (AF).

METHODS

Patients were grouped according to a HPSD (≥40 W) or LPLD (≤35 W) strategy. The primary endpoint was the 1-year recurrence of any atrial arrhythmia lasting ≥30 s, detected using three 14-day ambulatory continuous ECG monitoring. Procedural and safety endpoints were also evaluated. The primary analysis were regression models incorporating propensity scores yielding adjusted relative risk (RRa ) and mean difference (MDa ) estimates.

RESULTS

Of the 398 patients included in the AWARE Trial, 173 (43%) underwent HPSD and 225 (57%) LPLD ablation. The distribution of power was 50 W in 75%, 45 W in 20%, and 40 W in 5% in the HPSD group, and 35 W with 25 W on the posterior wall in the LPLD group. The primary outcome was not statistically significant at 30.1% versus 22.2% in HPSD and LPLD groups with RRa 0.77 (95% confidence interval [CI]) 0.55-1.10; p = .165). The secondary outcome of repeat catheter ablation was not statistically significant at 6.9% and 9.8% (RRa 1.59 [95% CI 0.77-3.30]; p = .208) respectively, nor was the incidence of any ECG documented AF during the blanking period: 1.7% versus 8.0% (RRa 3.95 [95% CI 1.00-15.61; p = .049) in the HPSD versus LPLD group respectively. The total procedure time was significantly shorter in the HPSD group (MDa 97.5 min [95% CI 84.8-110.4)]; p < .0001) with no difference in adjudicated serious adverse events.

CONCLUSIONS

An HPSD strategy was associated with significantly shorter procedural times with similar efficacy in terms of clinical arrhythmia recurrence. Importantly, there was no signal for increased harm with a HPSD strategy.

Sex-Specific Outcomes of LBBAP Versus Biventricular Pacing: Results From I-CLAS

BACKGROUND

Cardiac resynchronization therapy (CRT) using biventricular pacing (BVP) has been associated with greater clinical improvement in women than men. Recently, left bundle branch area pacing (LBBAP) has been shown to be an alternative form of CRT.

OBJECTIVES

The purpose of this study was to investigate sex-specific outcomes for death and heart failure events in a large, international, multicenter, cohort of patients undergoing CRT with BVP or LBBAP.

METHODS

In this international study of 1,778 patients (575 female and 1203 male), sex-specific survival analysis was performed to compare the effect of LBBAP-CRT relative to BVP-CRT on the combined endpoint of death or heart failure hospitalization (HFH), and secondary endpoints of HFH only, and death alone.

RESULTS

Female patients were more likely to have nonischemic cardiomyopathy and left bundle branch block (LBBB) and less likely to have hypertension, diabetes, or coronary artery disease than were male patients. Overall, female patients had a better result with LBBAP compared with BVP than did male patients, with a significant 36% reduction in death or HFH (HR: 0.64; 95% CI: 0.43 to 0.97; P = 0.03) and a significant 60% reduction in HFH alone (HR: 0.4; 95% CI: 0.24 to 0.69, P < 0.01). Women had a greater reduction in death or HFH among those with nonischemic cardiomyopathy (HR: 0.45 95% CI: 0.26 to 0.79; P < 0.01) and LBBB (HR: 0.49; 95% CI: 0.27 to 0.87; P < 0.01). Sex-specific echocardiographic outcomes were better in women than in men.

CONCLUSIONS

Women obtained significantly greater reductions in the combined endpoint of death or HFH (primarily driven by reduction in HFH) with LBBAP compared with BVP among patients requiring CRT than did men.

Do barrier dressings reduce cardiac implantable device infection: Protocol for a randomized controlled trial (BARRIER-PROTECT)

Background

Cardiac implantable electronic device (CIED) procedures can be associated with serious complications, including infection with significant mortality and morbidity, necessitating removal of the device and prolonged hospitalization. One potential pathophysiological mechanism is pocket contamination at the time of device implantation. Therefore, steps taken to prevent contamination at this stage can potentially reduce CIED infections.The barrier dressing, an adhesive material applied to the skin, has the potential to reduce the colonization of the surgical site with host flora that can predispose to infection. There are a limited number of randomized prospective studies on barrier dressing use during various surgeries, but it has never been systematically studied in CIED implantation.

Objectives

Do Barrier Dressings Reduce Cardiac Implantable Device Infection? (BARRIER-PROTECT trial; NCT04591366) is a single-centre, prospective, double-armed, single-blinded, randomized controlled trial designed to evaluate the use of an intra-operative adhesive barrier dressing to reduce the risk of end-of-procedure pocket swab positivity. We hypothesize that adhesive draping during implant procedures will reduce the risk of contamination from the skin flora. Also, we aim to investigate if the end-of-procedure pocket swab culture positivity can be used as a potential surrogate marker of CIED infection.

Methods and Design

Patients undergoing a second or later procedure on the same device pocket (pulse generator change, lead/pocket revision or upgrade) will be enrolled. Eligible and consenting patients will be equally randomized to the use of barrier dressing or not using an automated web-based system. Patients, but not the operator, will be blinded to the arm. The person performing the pocket swabs will also be blinded. The primary endpoint is the end-of-procedure pocket swab culture positivity. The main secondary endpoint is the CIED infection rate.

Discussion

This is the first randomized controlled trial to assess the effectiveness of using a barrier adhesive draping on reducing the end-of-procedure pocket swab culture positivity. In this study, we are exploring a low-cost intervention that may significantly reduce CIED infection. Also, having a valid surrogate marker for CIED infection at the time of implant will facilitate design of future clinical trials.

Comparison of Left Bundle Branch Area Pacing and Biventricular Pacing in Candidates for Resynchronization Therapy

BACKGROUND

Cardiac resynchronization therapy (CRT) with biventricular pacing (BVP) is a well established therapy in patients with reduced left ventricular ejection fraction (LVEF), heart failure, and wide QRS or expected frequent ventricular pacing. Left bundle branch area pacing (LBBAP) has recently been shown to be a safe alternative to BVP.

OBJECTIVES

The aim of this study was to compare the clinical outcomes between BVP and LBBAP among patients undergoing CRT.

METHODS

This observational study included patients with LVEF ≤35% who underwent BVP or LBBAP for the first time for Class I or II indications for CRT from January 2018 to June 2022 at 15 international centers. The primary outcome was the composite endpoint of time to death or heart failure hospitalization (HFH). Secondary outcomes included endpoints of death, HFH, and echocardiographic changes.

RESULTS

A total of 1,778 patients met inclusion criteria: 981 BVP, 797 LBBAP. The mean age was 69 ± 12 years, 32% were female, 48% had coronary artery disease, and mean LVEF was 27% ± 6%. Paced QRS duration in LBBAP was significantly narrower than baseline (128 ± 19 ms vs 161 ± 28 ms; P < 0.001) and significantly narrower compared to BVP (144 ± 23 ms; P < 0.001). Following CRT, LVEF improved from 27% ± 6% to 41% ± 13% (P < 0.001) with LBBAP compared with an increase from 27% ± 7% to 37% ± 12% (P < 0.001) with BVP, with significantly greater change from baseline with LBBAP (13% ± 12% vs 10% ± 12%; P < 0.001). On multivariable regression analysis, the primary outcome was significantly reduced with LBBAP compared with BVP (20.8% vs 28%; HR: 1.495; 95% CI: 1.213-1.842; P < 0.001).

CONCLUSIONS

LBBAP improved clinical outcomes compared with BVP in patients with CRT indications and may be a reasonable alternative to BVP.

A Randomized Trial of Lenient Versus Strict Arm Instruction Post Cardiac Device Surgery (LENIENT)

BACKGROUND

Arm restriction after cardiac implantable electronic device (CIED) placement is common practice despite minimal supporting evidence. Patients receive a range of restriction recommendations of variable durations with the goal of reducing complications such as wound dehiscence, infection, lead dislodgement, or hematoma formation. These movement limitations can lead to emotional stress and anxiety, complications such as frozen shoulder, and upper extremity venous thrombosis due to immobilization. There are no published clinical trials assessing the benefits and risks of arm restrictions post-CIED implant.

OBJECTIVES

The randomized trial of lenient vs strict arm and activity instruction post-CIED surgery (LENIENT trial; NCT04915261) is a single center nonblinded randomized prospective study designed to evaluate lenient compared to restrictive post-CIED care instructions. We hypothesize that there will be no significant difference in complications between the arms.

METHODS/DESIGN

All patients receiving a de novo CIED or those with upgrades and revisions requiring a new lead implant will be enrolled. Subjects are enrolled in a nonblinded randomized prospective trial with 6 randomly assigned 8-month periods, during which either a lenient or restrictive postoperative activity instructions will be given to all patients. Postoperative instructions are given at the time of discharge and further reinforced by recurrent interactive voice recognition (IVR) phone calls, text messages and emails. The requirement for individual consent has been waived. The primary end point is a composite of (1) lead dislodgement, (2) frozen shoulder, (3) upper extremity venous thrombosis, (4) clinically significant hematoma, and (5) infection occurring within 52 weeks of index surgery. The study is a noninferiority trial with a sample size of 1,250 per group.

DISCUSSION

This is the first large randomized clinical trial designed to establish an evidence-based postoperative standard of care for patients undergoing CIED implantation. This will improve the quality of care provided to patients and help guide implanting physicians providing postoperative care instructions.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04915261.

Standard vs Augmented Ablation of Paroxysmal Atrial Fibrillation for Reduction of Atrial Fibrillation Recurrence: The AWARE Randomized Clinical Trial

Importance

Recurrent atrial fibrillation (AF) commonly occurs after catheter ablation and is associated with patient morbidity and health care costs.

Objective

To evaluate the superiority of an augmented double wide-area circumferential ablation (WACA) compared with a standard single WACA in preventing recurrent atrial arrhythmias (AA) (atrial tachycardia, atrial flutter, or atrial fibrillation [AF]) in patients with paroxysmal AF.

Design, Setting, and Participants

This was a pragmatic, multicenter, prospective, randomized, open, blinded end point superiority clinical trial conducted at 10 university-affiliated centers in Canada. The trial enrolled patients 18 years and older with symptomatic paroxysmal AF from March 2015 to May 2017. Analysis took place between January and April 2022. Analyses were intention to treat.

Interventions

Patients were randomized (1:1) to receive radiofrequency catheter ablation for pulmonary vein isolation with either a standard single WACA or an augmented double WACA.

Main Outcomes and Measures

The primary outcome was AA recurrence between 91 and 365 days postablation. Patients underwent 42 days of ambulatory electrocardiography monitoring after ablation. Secondary outcomes included need for repeated catheter ablation and procedural and safety variables.

Results

Of 398 patients, 195 were randomized to the single WACA (control) arm (mean [SD] age, 60.6 [9.3] years; 65 [33.3%] female) and 203 to the double WACA (experimental) arm (mean [SD] age, 61.5 [9.3] years; 66 [32.5%] female). Overall, 52 patients (26.7%) in the single WACA arm and 50 patients (24.6%) in the double WACA arm had recurrent AA at 1 year (relative risk, 0.92; 95% CI, 0.66-1.29; P = .64). Twenty patients (10.3%) in the single WACA arm and 15 patients (7.4%) in the double WACA arm underwent repeated catheter ablation (relative risk, 0.72; 95% CI, 0.38-1.36). Adjudicated serious adverse events occurred in 13 patients (6.7%) in the single WACA arm and 14 patients (6.9%) in the double WACA arm.

Conclusions and Relevance

In this randomized clinical trial of patients with paroxysmal AF, additional ablation by performing a double ablation lesion set did not result in improved freedom from recurrent AA compared with a standard single ablation set.

Trial Registration

ClinicalTrials.gov Identifier: NCT02150902.

Characterization of arrhythmia substrate to ablate persistent atrial fibrillation (COAST-AF): Randomized controlled trial design and rationale

BACKGROUND

Atrial low voltage area (LVA) catheter ablation has emerged as a promising strategy for ablation of persistent atrial fibrillation (AF). It is unclear if catheter ablation of atrial LVA increases treatment success rates in patients with persistent AF.

OBJECTIVE

The primary aim of this trial is to assess the potential benefit of adjunctive catheter ablation of atrial LVA in addition to pulmonary vein isolation (PVI) in patients with persistent AF, when compared to PVI alone. The secondary aims are to evaluate safety outcomes, the quality of life and the healthcare resource utilization.

METHODS/DESIGN

A multicenter, prospective, parallel-group, 2-arm, single-blinded randomized controlled trial is under way (NCT03347227). Patients who are candidates for catheter ablation for persistent AF will be randomly assigned (1:1) to either PVI alone or PVI + atrial LVA ablation. The primary outcome is 18-month documented event rate of atrial arrhythmia (AF, atrial tachycardia or atrial flutter) post catheter ablation. Secondary outcomes include procedure-related complications, freedom from atrial arrhythmia at 12 months, AF burden, need for emergency department visits/hospitalization, need for repeat ablation for atrial arrhythmia, quality of life at 12 and 18 months, ablation time, and procedure duration.

DISCUSSION

Characterization of Arrhythmia Mechanism to Ablate Atrial Fibrillation (COAST-AF) is a multicenter randomized trial evaluating ablation strategies for catheter ablation. We hypothesize that catheter ablation of atrial LVA in addition to PVI will result in higher procedural success rates when compared to PVI alone in patients with persistent AF.

Effect of High-Intensity Interval Training in Patients With Atrial Fibrillation: A Randomized Clinical Trial

IMPORTANCE

Patients with atrial fibrillation (AF) experience poor functional capacity and quality of life (QOL). High-intensity interval training (HIIT) has been shown to elicit greater improvements in functional capacity and QOL compared with moderate to vigorous intensity continuous training (MICT) in other cardiovascular populations, yet HIIT remains understudied in AF.

OBJECTIVE

To compare the effects of 12 weeks of HIIT and MICT-based cardiovascular rehabilitation (CR) on functional capacity and general QOL in patients with persistent and permanent AF. Disease-specific QOL, resting heart rate (HR), time in AF, and physical activity (PA) levels were also assessed.

DESIGN, SETTING, AND PARTICIPANTS

This randomized clinical trial, conducted between November 17, 2015, and February 4, 2020, at a tertiary-care cardiovascular health center in Ottawa, Canada, recruited 94 patients with persistent and permanent AF.

INTERVENTIONS

High-intensity interval training (23 minutes: two 8-minute interval training blocks of 30-second work periods at 80%-100% of peak power output interspersed with 30-second recovery) or CR (60 minutes: continuous aerobic conditioning within 67%-95% of peak HR and 12-16 of 20 ratings of perceived exertion) twice weekly for 12 weeks.

MAIN OUTCOMES AND MEASURES

The primary outcomes were changes in functional capacity (6-minute walk test [6MWT] distance) and general QOL (Short Form 36) from baseline to 12 weeks' follow-up. Secondary outcomes included changes in disease-specific QOL (Atrial Fibrillation Severity Scale), resting HR, time in AF, and PA levels. An intention-to-treat analysis was used to compare changes between groups.

RESULTS

Of the 94 patients who consented, 86 participated (mean [SD] age, 69 [7] years; 57 [66.3%] men). No significant differences in improvements in 6MWT distance (mean [SD], 21.3 [34.1] vs 13.2 [55.2] m; P = .42) and general QOL (Physical Component Summary, 0.5 [6.1] vs 1.1 [4.9] points; P = .87) between HIIT and CR were observed. No significant differences in improvements in disease-specific QOL (AF symptoms: -1.7 [4.3] vs -1.5 [4] points, P = .59), resting HR (-3.6 [10.6] vs -2.9 [12.4] beats per minute, P = .63), and moderate to vigorous PA levels (37.3 [93.4] vs 14.4 [125.7] min/wk; P = .35) between HIIT and CR were detected. Participants attended a mean (SD) of 18.3 (6.1) (75.1%) HIIT sessions and 20.0 (4.5) (83.4%) CR sessions (P = .36).

CONCLUSIONS AND RELEVANCE

In this randomized clinical trial, twice-weekly 23-minute HIIT was as efficacious as twice-weekly 60-minute CR in improving functional capacity, general and disease-specific QOL, resting HR, and PA levels in patients with persistent and permanent AF.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02602457.

Arrhythmic events and mortality in patients with cardiogenic shock on inotropic support: results of the DOREMI randomized trial

BACKGROUND

Inotropic support is widely used in the management of cardiogenic shock (CS). Existing data on the incidence and significance of arrhythmic events in patients with CS on inotropic support is at high risk of bias.

METHODS

The DObutamine compaREd to MIlrinone (DOREMI) trial randomized patients to receive dobutamine or milrinone in a double-blind fashion. Patients with and without arrhythmic events (defined as arrhythmias requiring intervention or sustained ventricular arrhythmias) were compared to (1) identify factors associated with their occurrence and (2) examine their association with in-hospital mortality and secondary outcomes.

RESULTS

Ninety-two patients (47.9%) had arrhythmic events, occurring equally with dobutamine and milrinone (P=0.563). The need for vasopressor support at inotrope initiation and a history of atrial fibrillation were positively associated with arrhythmic events whereas predominant right ventricular dysfunction, previous myocardial infarction, and increasing left ventricular ejection fraction were negatively associated with them. Supraventricular arrhythmic events were not associated with mortality (RR 0.97, 95% CI 0.68-1.40, P=0.879) but were positively associated with resuscitated cardiac arrests and hospital length of stay. Ventricular arrhythmic events were positively associated with mortality (RR 1.66, 95% CI 1.13-2.43; P=0.026) and resuscitated cardiac arrests. Arrhythmic events were most often treated with amiodarone (97%) and electrical cardioversion (27%), which were not associated with mortality.

CONCLUSIONS

Clinically relevant arrhythmic events occur in approximately half of patients with CS treated with dobutamine or milrinone and are associated with adverse clinical outcomes. Five factors may help identify patients most at risk of arrhythmic events.

Augmented wide area circumferential catheter ablation for reduction of atrial fibrillation recurrence (AWARE) trial: Design and rationale

BACKGROUND

Recurrence of atrial fibrillation (AF) after a pulmonary vein isolation procedure is often due to electrical reconnection of the pulmonary veins. Repeat ablation procedures may improve freedom from AF but are associated with increased risks and health care costs. A novel ablation strategy in which patients receive "augmented" ablation lesions has the potential to reduce the risk of AF recurrence.

OBJECTIVE

The Augmented Wide Area Circumferential Catheter Ablation for Reduction of Atrial Fibrillation Recurrence (AWARE) Trial was designed to evaluate whether an augmented wide-area circumferential antral (WACA) ablation strategy will result in fewer atrial arrhythmia recurrences in patients with symptomatic paroxysmal AF, compared with a conventional WACA strategy.

METHODS/DESIGN

The AWARE trial was a multicenter, prospective, randomized, open, blinded endpoint trial that has completed recruitment (ClinicalTrials.gov NCT02150902). Patients were randomly assigned (1:1) to either the control arm (single WACAlesion set) or the interventional arm (augmented- double WACA lesion set performed after the initial WACA). The primary outcome was atrial tachyarrhythmia (AA; atrial tachycardia [AT], atrial flutter [AFl] or AF) recurrence between days 91 and 365 post catheter ablation. Patient follow-up included 14-day continuous ambulatory ECG monitoring at 3, 6, and 12 months after catheter ablation. Three questionnaires were administered during the trial- the EuroQuol-5D (EQ-5D) quality of life scale, the Canadian Cardiovascular Society Severity of Atrial Fibrillation scale, and a patient satisfaction scale.

DISCUSSION

The AWARE trial was designed to evaluate whether a novel approach to catheter ablation reduced the risk of AA recurrence in patients with symptomatic paroxysmal AF.

Safety and acute performance of paroxysmal and early persistent atrial fibrillation ablation using temperature-controlled, very high power, short duration catheter with a new radiofrequency generator

Funding Acknowledgements

Type of funding sources: Private company. Main funding source(s): Biosense Webster Inc.

Background/Introduction

The temperature-controlled contact force radiofrequency (RF) ablation catheter (QDM) has 6 thermocouples to maintain target catheter tip temperature and 3 tip microelectrodes for high local signal resolution. It has an enhanced irrigation profile to reduce char formation. Three prospective multicenter trials demonstrated safety and effectiveness of the QDM catheter using very high-power, short duration (vHPSD; 90W/4s), conventional power (CP; ≤50W) or combined modes. These studies were performed with an older RF generator. A new generator was developed to support the full suite of legacy, temperature controlled and multichannel ablation catheters, but has not yet been formally tested in a clinical setting.

Purpose

Evaluate safety and acute performance of the QDM catheter with the new 90W-enabled generator.

Methods

This prospective, multicenter study (4 Canadian sites) used vHPSD as primary mode for Pulmonary Vein (PV) isolation with overlapping 3mm lesion tags for anterior, inferior and roof of left atrium. Adjacent, non-overlapping lesions were used posteriorly to avoid esophageal heating. CP mode was used at operator discretion for thicker atrial tissue, touch ups, and non-PV triggers (Figure). Primary endpoint was confirmed entrance block in all PVs after adenosine and/or isoproterenol challenge. Acute procedural and safety data were assessed. Systematic char evaluation was performed.

Results

Effectiveness analysis included 38/40 subjects with mean 110-day follow up (mean age, 61.7 ± 9.5 years; 63.2% male). Hypertension (47.4%) and congestive heart failure (15.8%) were the most common comorbidities. Fourteen subjects were treated with version V0 of the generator, and 24 subjects were treated using version V1c which included further software adjustments to the power titration, and current response to optimize performance. Combination vHPSD/CP workflow was used for PV isolation in 28 (75.7%) subjects and vHPSD was used solely in 10. A non-study catheter was used in 1 subject during connectivity troubleshooting. Primary endpoint of entrance block confirmation was achieved in 37/38 subjects and in all 37 subjects treated with study catheter only. No incidences of char or device-related adverse events were reported. There were no noted differences in the endpoints evaluated between the V0 and V1c groups. Median (Q1/Q3) RF application times for ablating PVs was 13.0 min (9.0/16.0) for the entire cohort. Median (Q1/Q3) time to achieve PV isolation in vHPSD-only group was 9 (7/12) min, and 14 (11/18) min, respectively.

Conclusion(s)

Consistent with data from prior 3 clinical studies, QDM catheter with the new 90W-enabled generator demonstrated the acute safety and effectiveness of temperature-controlled AF ablation with short PV ablation time and no char observed.

Rhythm Monitoring Strategy and Arrhythmia Recurrence in Atrial Fibrillation Ablation Trials: A Systematic Review

Background

: The rhythm-monitoring strategy after catheter ablation (CA) for atrial fibrillation (AF) impacts the detection of atrial arrhythmia recurrence and is not well characterized. We performed a systematic review and meta-regression analysis to determine whether the duration and mode of rhythm monitoring after CA affects detection of atrial arrhythmia recurrence.

Methods

Databases were systematically searched for randomized controlled trials of adult patients undergoing first CA for AF from 2007 to 2021. Duration and strategy of rhythm monitoring were extracted. Meta-regression was used to identify any association between duration of monitoring and detection of atrial arrhythmia recurrence. The primary measure of outcome was single-procedure recurrence of atrial arrhythmia.

Results

The search strategy yielded 57 trial arms from 56 randomized controlled trials comprising 5322 patients: 36 arms of patients with paroxysmal AF (PAF), and 21 arms of patients with persistent AF (PeAF) or both PAF/PeAF. Intermittent monitoring was associated with detection of significantly less atrial arrhythmia recurrence than continuous monitoring in PAF arms (31.2% vs 46.9%, P = 0.001), but not in PeAF/PAF-PeAF combined arms (43.3% vs 63.6%, P = 0.12). No significant relationship was seen between the duration of intermittent rhythm monitoring and atrial arrhythmia recurrence detection in either the PAF (P = 0.93) or PeAF/PAF-PeAF combined arms (P = 0.20).

Conclusions

Continuous rhythm monitoring detected higher atrial arrhythmia recurrence rates, compared to intermittent rhythm monitoring, in patients with PAF. The duration of intermittent monitoring did not show a statistically significant relationship to the yield of arrhythmia detection, in near identical cohorts of trial subjects undergoing similar interventions, with clinical and research implications.

Post-operative pain following cardiac implantable electronic device implantation: insights from the BRUISE CONTROL trials

AIMS

Post-operative pain following cardiac implantable electronic device (CIED) insertion is associated with patient dissatisfaction, emotional distress, and emergency department visits. We sought to identify factors associated with post-operative pain and develop a prediction score for post-operative pain.

METHODS AND RESULTS

All patients from the BRUISE CONTROL-1 and 2 trials were included in this analysis. A validated Visual Analogue Scale (VAS) was used to assess the severity of pain related to CIED implant procedures. Patients were asked to grade the most severe post-operative pain, average post-operative pain, and pain on the day of the first post-operative clinic. Multivariable regression analyses were performed to identify predictors of significant post-operative pain and to develop a pain-prediction score. A total of 1308 patients were included. Multivariable regression analysis found that the presence of post-operative clinically significant haematoma {CSH; P value < 0.001; odds ratio (OR) 3.82 [95% confidence interval (CI): 2.37-6.16]}, de novo CIED implantation [P value < 0.001; OR 1.90 (95% CI: 1.47-2.46)], female sex [P value < 0.001; OR 1.61 (95% CI: 1.22-2.12)], younger age [<65 years; P value < 0.001; OR 1.54 (95% CI: 1.14-2.10)], and lower body mass index [<20 kg/m2; P value < 0.05; OR 2.05 (95% CI: 0.98-4.28)] demonstrated strong and independent associations with increased post-operative pain. An 11-point post-operative pain prediction score was developed using the data.

CONCLUSION

Our study has identified multiple predictors of post-operative pain after CIED insertion. We have developed a prediction score for post-operative pain that can be used to identify individuals at risk of experiencing significant post-operative pain.

Prevalence of Left Atrial Appendage Thrombus in Patients Anticoagulated With Direct Oral Anticoagulants: Systematic Review and Meta-analysis

BACKGROUND

Multiple studies have examined the prevalence of left atrial appendage thrombus (LAAT) in patients anticoagulated with direct oral anticoagulants (DOACs) and have reported conflicting results.

METHODS

Studies reporting the prevalence of LAAT on transesophageal echocardiography (TEE) after 3 or more weeks of DOAC therapy were identified. The proportions of anticoagulated patients diagnosed with LAAT were pooled using random-effects models. Prespecified subgroup analyses by the indication of TEE (pre-atrial fibrillation [AF] ablation vs cardioversion) and TEE strategy (routine use vs selective) were conducted via stratification.

RESULTS

Forty studies were identified: 22 full manuscripts and 18 abstracts. Only 11 studies performed TEE routinely. Most studies included patients with paroxysmal AF and low thromboembolic risk. The pooled prevalence of LAAT was 2.5% (95% confidence interval [1.6%-3.4%]). The prevalence of LAAT is lower in the pre-AF ablation group compared with pre-cardioversion (1.1% vs 4.0%, P = 0.033). Routine TEE strategy yielded a lower LAAT prevalence in both groups (0.1% vs 2.3%, P = 0.002 and 3.2% vs 5.8%, P = 0.432, respectively).

CONCLUSION

The reported prevalence of LAAT on TEE in patients treated with DOACs is highly variable. Factors associated with a high LAAT prevalence were pre-cardioversion indication and selective TEE strategy. Routine use of TEE before AF ablation may not be warranted.

High-power, short-duration atrial fibrillation ablation compared with a conventional approach: Outcomes and reconnection patterns

BACKGROUND

The effectiveness, safety, and pulmonary vein (PV) reconnection patterns of point-by-point high-power, short-duration (HPSD) ablation relative to conventional force-time integral (FTI)-guided strategies for atrial fibrillation (AF) ablation are unknown.

OBJECTIVES

To compare 1-year freedom from atrial arrhythmia (AA), complication rates, procedural times, and PV reconnection patterns with HPSD AF AF ablation versus an FTI-guided low-power, long-duration (LPLD) strategy.

METHODS

We compared consecutive patients undergoing a first ablation procedure for paroxysmal or persistent AF. The HPSD protocol utilized a power of 50 W and durations of 6-8 s posteriorly and 8-10 s anteriorly. The LPLD protocol was FTI-guided with a power of ≤25 W posteriorly (FTI ≥ 300g·s) and ≤35 W anteriorly (FTI ≥ 400g·s).

RESULTS

In total, 214 patients were prospectively included (107 HPSD, 107 LPLD). Freedom from AA at 1 year was achieved in 79% in the HPSD group versus 73% in the LPLD group (p = .339; adjusted hazard ratio with HPSD, 0.67; 95% confidence interval, 0.36-1.23; p < .004 for non-inferiority). Procedure duration was shorter in the HPSD group (229 ± 60 vs. 309 ± 77 min; p < .005). Patients undergoing repeat ablation had a higher propensity for reconnection at the right PV carina in the HPSD group compared with the LPLD group (14/30 = 46.7% vs. 7/34 = 20.6%; p = .035). There were no differences in complication rates.

CONCLUSION

HPSD AF ablation resulted in similar freedom from AAs at 1 year, shorter procedure times, and a similar safety profile when compared with an LPLD ablation strategy. Patients undergoing HPSD ablation required more applications at the right carina to achieve isolation, and had a significantly higher rate of right carinal reconnections at redo procedures.

The 2020 Canadian Cardiovascular Society/Canadian Heart Rhythm Society Comprehensive Guidelines for the Management of Atrial Fibrillation

The Canadian Cardiovascular Society (CCS) atrial fibrillation (AF) guidelines program was developed to aid clinicians in the management of these complex patients, as well as to provide direction to policy makers and health care systems regarding related issues. The most recent comprehensive CCS AF guidelines update was published in 2010. Since then, periodic updates were published dealing with rapidly changing areas. However, since 2010 a large number of developments had accumulated in a wide range of areas, motivating the committee to complete a thorough guideline review. The 2020 iteration of the CCS AF guidelines represents a comprehensive renewal that integrates, updates, and replaces the past decade of guidelines, recommendations, and practical tips. It is intended to be used by practicing clinicians across all disciplines who care for patients with AF. The Grading of Recommendations, Assessment, Development and Evaluations (GRADE) system was used to evaluate recommendation strength and the quality of evidence. Areas of focus include: AF classification and definitions, epidemiology, pathophysiology, clinical evaluation, screening and opportunistic AF detection, detection and management of modifiable risk factors, integrated approach to AF management, stroke prevention, arrhythmia management, sex differences, and AF in special populations. Extensive use is made of tables and figures to synthesize important material and present key concepts. This document should be an important aid for knowledge translation and a tool to help improve clinical management of this important and challenging arrhythmia.

Evaluation of a novel cardioversion intervention for atrial fibrillation: the Ottawa AF cardioversion protocol

AIMS

Electrical cardioversion is commonly performed to restore sinus rhythm in patients with atrial fibrillation (AF), but it is unsuccessful in 10-12% of attempts. We sought to evaluate the effectiveness and safety of a novel cardioversion protocol for this arrhythmia.

METHODS AND RESULTS

Consecutive elective cardioversion attempts for AF between October 2012 and July 2017 at a tertiary cardiovascular centre before (Phase I) and after (Phase II) implementing the Ottawa AF cardioversion protocol (OAFCP) as an institutional initiative in July 2015 were evaluated. The primary outcome was cardioversion success, defined as ≥2 consecutive sinus beats or atrial-paced beats in patients with implanted cardiac devices. Secondary outcomes were first shock success, sustained success (sinus or atrial-paced rhythm on 12-lead electrocardiogram prior to discharge from hospital), and procedural complications. Cardioversion was successful in 459/500 (91.8%) in Phase I compared with 386/389 (99.2%) in Phase II (P < 0.001). This improvement persisted after adjusting for age, body mass index, amiodarone use, and transthoracic impedance using modified Poisson regression [adjusted relative risk 1.08, 95% confidence interval (CI) 1.05-1.11; P < 0.001] and when analysed as an interrupted time series (change in level +9.5%, 95% CI 6.8-12.1%; P < 0.001). The OAFCP was also associated with greater first shock success (88.4% vs. 79.2%; P < 0.001) and sustained success (91.6% vs 84.7%; P=0.002). No serious complications occurred.

CONCLUSION

Implementing the OAFCP was associated with a 7.4% absolute increase in cardioversion success and increases in first shock and sustained success without serious procedural complications. Its use could safely improve cardioversion success in patients with AF.

CLINICAL TRIAL NUMBER

www.clinicaltrials.gov ID: NCT02192957.

Catheter Ablation of Low-Voltage Areas for Persistent Atrial Fibrillation: Procedural Outcomes Using High-Density Voltage Mapping

BACKGROUND

Several approaches have been proposed to address the challenge of catheter ablation of persistent atrial fibrillation (AF). However, the optimal ablation strategy is unknown. We sought to evaluate the efficacy of pulmonary vein isolation (PVI) plus low-voltage area (LVA) ablation using contemporary high-density mapping to identify LVA in patients with persistent AF.

METHODS

Consecutive patients accepted for AF catheter ablation were studied. High-density bipolar voltage mapping data were acquired in sinus rhythm using multipolar catheters to detect LVA (defined as bipolar voltage < 0.5 mV). Semiautomated impedance-based software was used to ensure catheter contact during data collection. Patients underwent PVI + LVA ablation (if LVA present).

RESULTS

A total of 145 patients were studied; 95 patients undergoing PVI + LVA ablation were compared with 50 controls treated with PVI only. Average age was 61 ± 10 years, and 80% were male. Baseline characteristics were comparable. Freedom from atrial tachycardia/AF at 18 months was 72% after PVI + LVA ablation vs 58% in controls (P = 0.022). Median procedure duration (273 [240, 342] vs 305 [262, 360] minutes; P = 0.019) and radiofrequency delivery (50 [43, 63] vs 55 [35, 68] minutes; P = 0.39) were longer in the PVI + LVA ablation group. Multivariable analysis showed that the ablation strategy (PVI + LVA) was the only independent predictor of freedom from atrial tachycardia/AF (hazard ratio, 0.53; 95% confidence interval, 0.29-0.96; P = 0.036). There were no adverse safety outcomes associated with LVA ablation.

CONCLUSIONS

An individualized strategy of high-density mapping to assess the atrial substrate followed by PVI combined with LVA ablation is associated with improved outcomes. Adequately powered randomized clinical trials are needed to determine the role of PVI + LVA ablation for persistent AF.

A new electrocardiographic definition of left bundle branch block (LBBB) in patients after transcatheter aortic valve replacement (TAVR)

BACKGROUND

Current LBBB definitions cannot always distinguish LBBB from left ventricular conduction delay. Only patients with LBBB are expected to normalize with His bundle pacing. Patients who develop new LBBB immediately post transcatheter aortic valve replacement (TAVR) provide an excellent model to define electrocardiogram (ECG) features of LBBB. We sought to describe their ECG features and develop a new ECG definition of LBBB.

METHODS

We screened ECGs from 264 consecutive patients who underwent TAVR at the University of Ottawa Heart Institute. Patients with a baseline QRS of ≤100 ms who developed QRS ≥120 ms immediately after TAVR were included. Two electrocardiologists reviewed all ECG independently. Baseline demographics and echocardiographic data were retrospectively collected.

RESULTS

36 patients were included in the analysis. The median age was 85.5 years (IQR, 81.8-89 years) and 52.8% were males. The minimum QRS duration was 126 ms. The median QRS axis was -18° (IQR, -40-4.5°), which is 18.5° leftward compared to the median QRS axis before TAVR. Fourteen patients (38.9%) had left axis deviation. All patients had a notched/slurred R wave in at least one lateral lead and an R wave duration of ≤20 ms in V1 when present.

CONCLUSION

We developed a new ECG definition of LBBB that includes 2 novel findings: notching/slurring of the R wave in at least one lateral lead and an R wave ≤20 ms in V1. Further larger studies are warranted to confirm these findings.

2018 Focused Update of the Canadian Cardiovascular Society Guidelines for the Management of Atrial Fibrillation

The Canadian Cardiovascular Society (CCS) Atrial Fibrillation Guidelines Committee provides periodic reviews of new data to produce focused updates that address clinically important advances in atrial fibrillation (AF) management. This 2018 Focused Update addresses: (1) anticoagulation in the context of cardioversion of AF; (2) the management of antithrombotic therapy for patients with AF in the context of coronary artery disease; (3) investigation and management of subclinical AF; (4) the use of antidotes for the reversal of non-vitamin K antagonist oral anticoagulants; (5) acute pharmacological cardioversion of AF; (6) catheter ablation for AF, including patients with concomitant AF and heart failure; and (7) an integrated approach to the patient with AF and modifiable cardiovascular risk factors. The recommendations were developed using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) standards. Individual studies and literature were reviewed for quality and bias; the literature review process and evidence tables are included as Supplementary Material and are available on the CCS Web site. Details of the updated recommendations are presented, along with their background and rationale. This document is linked to an updated summary of all CCS AF guidelines recommendations, from 2010 to the present 2018 Focused Update, which is provided in the Supplementary Material.

Value of VKORC1 (-1639G>A) rs9923231 genotyping in predicting warfarin dose: A replication study in South Indian population

OBJECTIVE

Warfarin is the most commonly prescribed oral anticoagulant, although having a narrow therapeutic index and wide interindividual variability. The aim of this study was to replicate the utility of VKORC1 (-1639G>A) rs9923231 genotyping in predicting the mean daily dose and to evaluate its ability to categorize warfarin-treated patients to high-, intermediate-, or low-dose categories in the South Indian population.

MATERIALS AND METHODS

A cohort of 222 warfarin-treated patients was genotyped using restriction fragment length polymorphism method. The influence of the rs9923231 polymorphism on the variations in the mean daily dose was compared using one-way analysis of variance and linear regression analysis. Discriminatory ability of the rs9923231 polymorphism to group the patients into ordered dose categories was assessed by estimating the proportional odds ratios using the ordered logit regression analysis.

RESULTS

The frequency of AA genotype and A allele in the study sample was found to be 1.8% and 9.23%, respectively, which was similar to reports from other South Indian populations. The mean daily dose required to achieve the optimum international normalized ratio was significantly lower in AA homozygous genotype carriers (3.99 ± 1.67 mg/day) and GA heterozygous (4.26 ± 1.57 mg/day) compared to the GG genotype carriers (5.51 ± 2.13 mg/day), p = 0.003. The A allele carriers (GA+AA genotypes) had a 3.23 higher odds of being grouped as a low-dose requiring category compared to non-carriers (95% CI 1.49-6.98, p = 0.003).

CONCLUSIONS

These preliminary results strongly support the use of VKORC1 (-1639G>A) rs9923231 polymorphism for genetically guided initial warfarin dosing in South Indian patients with heart valve replacements.

Characterization of Low-Voltage Areas in Patients With Atrial Fibrillation: Insights From High-Density Intracardiac Mapping

BACKGROUND

There is limited data on the scar burden in patients with atrial fibrillation (AF). In this study, we sought to evaluate the presence and extent of an abnormal left atrial (LA) substrate in patients with paroxysmal or persistent AF.

METHODS

Consecutive patients who underwent initial AF catheter ablation were prospectively enrolled. Endocardial voltage mapping was acquired in sinus rhythm using multipolar mapping catheters. Automated software was used to ensure homogeneous data collection. Assessment of low-voltage area (LVA) was performed by a reviewer blinded to clinical details.

RESULTS

One hundred and four patients were prospectively enrolled; 69 had paroxysmal and 35 persistent AF. The mean LA volume was 159 ± 48 mL, and the average number of LA points collected was 1308 ± 1065. Atrial LVAs were present in 23 of 69 (33%) subjects with paroxysmal and 20 of 35 (57%) with persistent AF (P = 0.02). Amongst 43 of 104 patients with scar, the average extent of LVA was 19.4 ± 21.6 cm² and the mean percentage area was 7.6 ± 8.8%. Univariate analysis showed that age, LA volume, and persistent AF were associated with the presence of LVA. Multivariable analysis showed that age (odds ratio [OR] 1.05; 95% confidence interval [CI] 1.00-1.11; P = 0.046) and LA volume (OR 1.02; 95% CI 1.01-1.04; P < 0.001) remained predictors of LVA. AF classification (persistent vs paroxysmal) was not a predictor of an abnormal atrial substrate (OR 1.34; 95% CI 0.4-3.9; P = 0.56).

CONCLUSIONS

There is wide variability in the presence and extent of LVA in patients with paroxysmal or persistent AF. Age and LA volume were predictors of LVA. There was no correlation between AF classification and the presence of LVA.

Multiple inappropriate implantable cardiac defibrillator therapies in rapid succession

Inappropriate implantable cardiac defibrillator (ICD) shocks are associated with significant morbidity and have the potential to trigger ventricular arrhythmias, cardiac decompensation, and death. We present a case of multiple inappropriate ICD therapies in rapid succession due electromagnetic interference from a Dr‐Ho's transcutaneous electric nerve stimulator machine, and subsequently from a faulty electrical outlet.

Lack of association of mirSNP rs11174811 in AVPR1A gene with arterial blood pressure and hypertension in South Indian population

Epigenetic regulation of arterial blood pressure mediated through mirSNPs in renin-angiotensin aldosterone system (RAAS) genes is a less explored hypothesis. Recently, the mirSNP rs11174811 in the 3'UTR of the AVPR1A gene was associated with higher arterial blood pressure in a large study population from the Study of Myocardial Infarctions Leiden (SMILE). The aim of the present study was to replicate the association of mirSNP rs11174811 with blood pressure outcomes and hypertension in a south Indian population. Four hundred and fifteen hypertensive cases and 416 normotensive controls were genotyped using a 5' nuclease allelic discrimination assay. Logistic regression was used to test the association of mirSNP rs11174811 with the hypertension phenotype. Censored normal regression was used to test the association of the polymorphism with continuous blood pressure outcomes such as systolic and diastolic blood pressure. The mirSNP rs11174811 did not show any significant association with hypertension. The adjusted odds ratio was 1.02, with 95% CI of 0.72 to 1.45 (p = 0.909). The mean systolic and diastolic blood pressure values were not significantly different across the three genotypic groups, between hypertensives and normotensives, or when stratified by gender. Despite having a similar minor allele frequency (MAF) of 14.5% compared with the SMILE cohort, our results did not support an association of the mirSNP rs11174811 with the hypertension phenotype or with continuous blood pressure outcomes in the south Indian population.

Efficacy and safety of driver-guided catheter ablation for atrial fibrillation: A systematic review and meta-analysis

INTRODUCTION

Targeting localized drivers (electrical rotors or focal impulses) during catheter ablation for atrial fibrillation (AF) has been proposed as a strategy to improve procedural success. However, the strength and quality of the evidence to support this approach is unclear.

METHODS AND RESULTS

Clinical studies reporting efficacy or safety outcomes of driver-guided ablation for AF were identified in Medline, Embase, the Cochrane Central Register of Controlled Trials, the Cochrane Database of Systematic Reviews, Pubmed, and conference abstracts from major scientific meetings. Random-effects meta-analysis of efficacy outcomes from controlled studies was performed. Thirty-one reports from 30 studies were included: two randomized controlled trials, five nonrandomized controlled studies, and 23 uncontrolled studies. In controlled studies, driver-guided ablation has been associated with higher rates of acute AF termination (RR 2.08, 95% CI 1.43-3.05; P < 0.001) and increased freedom from AF/atrial tachycardia (AT) at ≥1 year (RR 1.34, 95% CI 1.05-1.70; P = 0.02). Similar rates of procedural complications have been reported between ablation strategies. Overall, current data on driver-guided ablation are predominantly from nonrandomized studies with considerable heterogeneity in mapping and ablation strategies used and in clinical outcomes reported.

CONCLUSION

Pooled data on the efficacy of AF driver-guided catheter ablation suggest increased freedom from AF/AT relative to conventional strategies. However, most studies are nonrandomized and of moderate quality. Though promising data exist, there remains no conclusive evidence for the efficacy of AF driver ablation. Robust data from randomized trials are needed.

Three-year outcomes and reconnection patterns after initial contact force guided pulmonary vein isolation for paroxysmal atrial fibrillation

BACKGROUND AND OBJECTIVE

Contact force (CF) sensing is a novel technology used for catheter ablation of atrial fibrillation (AF). We compared the single procedure success of CF-guided pulmonary vein isolation (PVI) with that of non-CF guided PVI during a 3-year (1,095 days) follow up period and analyzed the pattern of pulmonary vein (PV) reconnection.

METHODS

A cohort of 167 subjects (68 CF vs. 99 non-CF) with paroxysmal AF were included in the study. Atrial arrhythmia (AA) recurrence was defined as documented AF, atrial flutter, or atrial tachycardia lasting >30 seconds and occurring after 90 days.

RESULTS

Subjects in the CF group showed a statistically nonsignificant improvement in AA free survival compared to those in the non-CF group (66.2% vs. 51.5%; P value: 0.06). A greater propensity for reconnection was noted around the right-sided PVs compared to left-sided PVs related in both catheter ablation groups. For example, in the CF group 36% of right-sided segments reconnected compared to 16% of left-sided segments (P value <0.01).

CONCLUSIONS

A greater propensity for reconnection was noted around the right sided PV segments in both the CF and non-CF groups. The explanation for this finding was related to greater catheter instability around the right sided veins. Further research is needed to explore the utility of a "real-time" composite indicator that includes RF energy, CF and catheter stability in predicting transmural lesion formation during catheter ablation.

Spatial Relationships of Complex Fractionated Atrial Electrograms and Continuous Electrical Activity to Focal Electrical Sources: Implications for Substrate Ablation in Human Atrial Fibrillation

OBJECTIVES

This study sought to evaluate the spatial relationships of focal electrical sources (FSs) to complex fractionated atrial electrograms (CFAE) and continuous electrical activity (CEA).

BACKGROUND

Fractionated atrial electrograms have been associated with atrial fibrillation (AF) drivers in computational studies and represent ablation targets in the management of persistent AF.

METHODS

We included a subset of 66 patients (age: 63 [56, 67] years, 69% persistent AF) with electroanatomic data from the SELECT AF (Selective complex fractionated atrial electrograms targeting for atrial fibrillation) randomized control trial that compared the efficacy of CFAE with CEA ablation in AF patients undergoing pulmonary vein antral ablation. Focal sources were identified based on bipolar electrogram periodicity and QS unipolar electrogram morphology.

RESULTS

A total of 77 FSs (median: 1 [1st quartile, 3rd quartile: 1, 2] per patient) were identified most commonly in the pulmonary vein antrum and left atrial appendage. The proportions of FSs inside CFAE and CEA regions were similar (13% vs. 1.3%, respectively; p = 0.13). Focal sources were more likely to be on the border zone of CFAEs than in CEAs (49% vs. 7.8%, respectively; p = 0.012). Following ablation, 53% of patients had ≥1 unablated extrapulmonary vein FS. The median number of unablated FS was higher in patients with AF recurrence post ablation than in patients without (median: 1 [0, 1] vs. 0 [0, 1], respectively; p = 0.026).

CONCLUSIONS

One-half of the FSs detected during AF localized to the border of CFAE areas, whereas most of the FSs were found outside CEA areas. CFAE or CEA ablation leaves a number of FS unablated, which is associated with AF recurrence. These findings suggest that many CFAEs may arise from passive wave propagation, remote from FS, which may limit their therapeutic efficacy in AF substrate modification.

A case of pacemaker "malfunction". Should I intervene?

A 53year old lady was noted to have persistent bradycardia in the recovery unit shortly after a dual chamber permanent pacemaker (PPM) was implanted. The patient was asymptomatic. The pacemaker was implanted for symptomatic intermittent complete heart block. She had surgical closure of an atrial septal defect three decades earlier and a previous tricuspid valve replacement with concomitant biatrial cryomaze procedure for paroxysmal atrial fibrillation.

Evaluating genomic DNA extraction methods from human whole blood using endpoint and real-time PCR assays

The extraction of genomic DNA is the crucial first step in large-scale epidemiological studies. Though there are many popular DNA isolation methods from human whole blood, only a few reports have compared their efficiencies using both end-point and real-time PCR assays. Genomic DNA was extracted from coronary artery disease patients using solution-based conventional protocols such as the phenol-chloroform/proteinase-K method and a non-phenolic non-enzymatic Rapid-Method, which were evaluated and compared vis-a-vis a commercially available silica column-based Blood DNA isolation kit. The appropriate method for efficiently extracting relatively pure DNA was assessed based on the total DNA yield, concentration, purity ratios (A₂₆₀/A₂₈₀ and A₂₆₀/A₂₃₀), spectral profile and agarose gel electrophoresis analysis. The quality of the isolated DNA was further analysed for PCR inhibition using a murine specific ATP1A3 qPCR assay and mtDNA/Y-chromosome ratio determination assay. The suitability of the extracted DNA for downstream applications such as end-point SNP genotyping, was tested using PCR-RFLP analysis of the AGTR1-1166A>C variant, a mirSNP having pharmacogenetic relevance in cardiovascular diseases. Compared to the traditional phenol-chloroform/proteinase-K method, our results indicated the Rapid-Method to be a more suitable protocol for genomic DNA extraction from human whole blood in terms of DNA quantity, quality, safety, processing time and cost. The Rapid-Method, which is based on a simple salting-out procedure, is not only safe and cost-effective, but also has the added advantage of being scaled up to process variable sample volumes, thus enabling it to be applied in large-scale epidemiological studies.