ELECTROPHYSIOLOGY
Our CIRQ research group works alongside the KGH electrophysiology physicians and device clinic to participate in groundbreaking studies spanning a broad range of clinical and investigational work. Current projects include evaluating new ablation mapping techniques to improve patient outcomes, optimizing device programming to enhance performance, collaborating with leading medical device companies on large scale device registries, and enrolling patients in randomized controlled trials comparing medical therapy with ablation in long-term outcome studies. Through this work, we strive to improve patient outcomes and advance the field of electrophysiology.
Research Projects
AMPLIFY EP Registry: Evaluating Real-World Use of the TactiFlex Ablation System
PI:
The AMPLIFY EP Registry is a prospective, multi-center, observational study designed to capture real-world clinical experience with the TactiFlex Ablation Catheter system in the treatment of atrial fibrillation (AF). Patient assessments are conducted before the procedure, at the time of ablation, and one year post-procedure. Study objectives include: Evaluating clinical outcomes, including procedural efficiency, safety, and long-term effectiveness. Assessing the impact of high-power, short-duration ablation on workflow, practice patterns, and operator experience.
Hearts in Rhythm Organization (HiRO) National Registry and Biobank
PI: Dr. Chris Simpson
The Hearts in Rhythm Organization (HiRO) is a national network of Canadian researchers/clinicians, working towards a better understanding of the rare genetic causes of sudden cardiac death (SCD). HiRO began in 2016 with adult and pediatric electrophysiology centres across Canada who have been working together since 2004, to gather data and bio samples in four national data registries and bio banks: • CASPER (Cardiac Arrest Survivors with Preserved Ejection Fraction Registry,) • National Long QT syndrome (LQTS) Registry • National Arrhythmogenic Right Ventricular cardiomyopathy (ARVC) Registry • National Brugada Syndrome Registry This current protocol provides a system wide mechanism to allow the National investigator group to work together more efficiently to ensure the inclusion of all Canadians affected by the inherited causes of SCD to help ensure standardized quality care for this population in all provinces with embedded opportunity for all individuals to participate in research.
LEFT Bundle Pacing vs Standard RV Pacing for Heart Failure
PI: Dr. Cengiz Burak
High-burden right ventricular (RV) pacing has been associated with increased cardiovascular mortality, a higher incidence of heart failure (HF), deterioration of left ventricular (LV) function, and accelerated onset of atrial fibrillation (AF). A high percentage of ventricular pacing and wider paced QRS duration—particularly in patients with low-to-normal baseline LV ejection fractions—are independent risk factors for pacing-induced cardiomyopathy. Left bundle branch pacing (LBBP) has recently emerged as a promising alternative pacing strategy. By closely replicating the heart’s native electrical conduction, LBBP may help preserve LV synchrony and reduce the risk of pacing-induced LV dysfunction. This study is a multi-centre randomized double-blinded controlled trial of two treatment groups. Our objective is to assess whether LBBP reduces adverse cardiovascular outcomes compared to traditional RV pacing in patients with AV block and preserved/mildly reduced LVEF.
PEFA: Paced Electrogram Feature Analysis for Ablation Targeting in Ischemic Ventricular Tachycardia
PI: Dr. Damian Redfearn
Catheter ablation for ventricular arrhythmias is a well-established therapy shown to reduce ventricular tachycardia (VT) storms and implantable cardioverter-defibrillator (ICD) shocks. However, recurrence rates remain high, highlighting the need for more effective ablation strategies. The VANISH trial, the largest randomized controlled study to date, demonstrated that catheter ablation is superior to escalating antiarrhythmic drug therapy. While it led to a modest reduction in VT storms and ICD shocks, 42% of patients still experienced recurrent shocks, and 64% received appropriate antitachycardia pacing (ATP) despite contemporary ablation techniques. This underlines the complexity of the arrhythmic substrate and the need for better tools to guide ablation. Our study investigates whether catheter ablation guided by Programmed Electrical Field Analysis (PEFA) can improve clinical outcomes in patients with a history of myocardial infarction and sustained VT or ventricular fibrillation (VF). Primary Objective: To evaluate whether PEFA-guided catheter ablation reduces adverse clinical outcomes in this high-risk patient population. Secondary Objective: To compare clinical outcomes of PEFA-guided ablation with published data on patients with prior myocardial infarction and sustained VT/VF, focusing on rates of VT recurrence, ICD shocks, and ATP delivery.
Targeted Therapy with Glycogen Synthase Kinase-3 Inhibition for Arrhythmogenic Cardiomyopathy
PI: Dr. Chris Simpson
Arrhythmogenic cardiomyopathy (ACM) is a heritable structural heart disease marked by progressive myocardial fibrosis, predisposing patients to malignant ventricular arrhythmias and sudden cardiac death (SCD). While ACM most commonly affects the right ventricle—known as arrhythmogenic right ventricular cardiomyopathy (ARVC)—its development is influenced by both genetic and environmental factors, including exercise. The most well-established genetic contributors to ACM are mutations in desmosomal proteins, key components of the intercalated disc that mediate intercellular adhesion in cardiac tissue. Emerging evidence implicates Glycogen Synthase Kinase-3 (GSK3)—an enzyme involved in various intracellular signaling pathways, including the Wnt/β-catenin pathway—in ACM pathogenesis. Suppression of this pathway has been linked to disease progression, suggesting that GSK3 inhibition may offer a novel therapeutic approach. Study Overview: This is a multicenter, randomized (1:1), double-blind, placebo-controlled clinical trial evaluating tideglusib, a GSK3 inhibitor, in patients with ACM. Primary Objective: • To determine whether tideglusib reduces the average number of premature ventricular contractions (PVCs) per 24 hours (measured via 7-day Holter monitoring) compared to placebo after 6 months of treatment. Secondary Objectives: • To assess whether tideglusib improves ventricular strain parameters as measured by echocardiography over 6 months. • To evaluate whether tideglusib reduces the frequency of ICD therapies (including shocks and anti-tachycardia pacing). • To determine if tideglusib lowers the incidence of sustained ventricular tachycardia (VT) compared to placebo over the treatment period.
VANISH-2: Ventricular Tachycardia Antiarrhythmics or AblatioN In Structural Heart Disease 2
PI: Dr. Damian Redfearn
Background Implantable cardioverter-defibrillators (ICDs) are highly effective in preventing sudden cardiac death by terminating ventricular tachycardia (VT), often without the need for shocks. However, ICDs do not prevent the recurrence of VT, and the optimal first-line treatment—catheter ablation or antiarrhythmic drug (AAD) therapy—remains unclear. While prior trials have shown that both catheter ablation and AADs like amiodarone and sotalol can reduce VT recurrence, no study has directly compared these approaches as initial therapy. The VANISH trial demonstrated that ablation is superior to escalated drug therapy in patients with VT refractory to initial treatment, but more evidence is needed to guide first-line decisions—especially with growing support for earlier intervention. Study Overview This randomized clinical trial evaluates whether catheter ablation or antiarrhythmic drug therapy is more effective as the initial treatment for sustained monomorphic VT in patients with a history of myocardial infarction. Primary Objective To determine which approach—ablation or AAD therapy—provides better control of key clinical outcomes. Secondary Objectives The trial will also compare the two strategies based on: All-cause mortality, ICD therapies including antitachycardia pacing and shocks (overall and beyond 14 days), VT storm incidence, Sustained VT not treated by ICD, VT requiring conversion by external or pharmacologic methods, Inappropriate ICD shocks, Overall ICD shock burden, Quality of life, Cost-effectiveness
OCEAN: Optimal Anticoagulation for Higher Risk Patients Post-Catheter Ablation for Atrial Fibrillation Trial
PI: Dr. Damian Redfearn
The OCEAN trial will compare medical approaches for stroke prevention in people who have atrial fibrillation (AF) but have undergone a successful ablation to eliminate or substantially reduce the arrhythmia. AF is normally associated with an increased risk of stroke; this risk can be reduced using treatment with oral anticoagulants. However, it is unknown if elimination or substantial reduction of AF with an ablation procedure also reduces the risk of stroke associated with AF. If it does reduce the stroke risk, then patients who have a successful ablation may not need to continue on life-long oral anticoagulant therapy. However, this benefit has to be weighed against the risk of ongoing stroke despite significant AF reduction. This trial will compare a strategy of oral anticoagulant therapy with rivaroxaban to an aspirin a day after successful AF ablation. The primary outcome will be a composite of stroke, systemic embolism and silent cerebral infarction as defined by cerebral magnetic resonance imaging. A pre-specified subset of patients will also undergo insertion of an implantable loop recorder capable of automated AF detection. Over 1500 patients will be enrolled overall. Currently, this study is in analysis phase.
RAFT-PermAF: Resynchronization/​Defibrillation for Ambulatory Heart Failure Trial in Patients With Permanent Atrial Fibrillation
PI: Dr. Damian Redfearn
Atrial fibrillation (AF) and heart failure (HF) are two common heart conditions that are encountered with an increase in death and suffering. When both these two conditions occur in a patient, the patient's prognosis is poor with a reduced quality of life and impaired heart function. These patients have enlarged hearts, specifically the left ventricle (major pumping chamber), which impairs the heart's pumping capacity, leading to symptoms such as fatigue, shortness of breath from any type of exertion, and swelling, usually of the feet and ankles. In these HF patients who are in AF all of the time, who would otherwise be a suitable candidate for an implantable defibrillator to prevent sudden cardiac death, we would like to determine whether adding pacing of both ventricles will reduce heart size (left ventricular end systolic volume index LVESVi) as measured by ultrasound, which can improve its function and help the heart pump more efficiently. Other studies have shown that adding pacing to both ventricles is of benefit in HF patients with mild to moderate symptoms and have a regular heart rhythm. The Investigators now want to explore if this therapy will benefit those patients with a permanent irregular heart rhythm (AF). This study is concluded and is in manuscript preparation stage.
RAFT- AF Trial Extend: Randomized Ablation-based AF Rhythm-control Versus Rate-control in Patients With HF and High-burden AF Extend
PI: Dr. Damian Redfearn
The RAFT-AF Extend Trial is a continued follow up of patients enrolled in the original RAFT-AF Study (ClinicalTrials.gov, NCT01420393), which evaluated whether ablation-based rhythm-control compared to rate-control improves clinical outcomes in patients with heart failure and atrial fibrillation. It was a randomised, open-label clinical trial, with blinded endpoint adjudication, conducted in 21 institutions in four countries. Patients with atrial fibrillation, New York Heart Association class II-III heart failure, and elevated NT-proBNP were included. Patients were randomized (1:1) to ablation-based rhythm-control or rate-control, stratified by left ventricular ejection fraction (≤45% and >45%). Ablation-based rhythm-control consisted of pulmonary vein isolation in paroxysmal atrial fibrillation, and additional ablation for persistent atrial fibrillation. Rate-control included AV-nodal blocking agents and AV node ablation with permanent pacing. The primary outcome was a composite of mortality and heart failure events, with a minimum follow up of two years. Secondary outcomes included left ventricular ejection fraction, quality of life, six-minute walk test and NT-proBNP. The primary analysis was intention-to-treat. From December 1, 2011, to January 20, 2018, 411 patients were randomised to ablation-based rhythm-control (n=214) or rate-control (n=197). The primary outcome occurred in 50 (23·4%) patients in the ablation-based rhythm-control group and 64 (32·5%) patients in the rate-control group (hazard ratio 0·71 95% CI (0·49, 1·03), p=0·066). Quality of life, six-minute walk distance, left ventricular ejection fraction, and NT-proBNP demonstrated greater improvements in the ablation-based rhythm-control group. In patients with high burden atrial fibrillation and heart failure, there was no statistically significant reduction of all-cause mortality or heart failure events with ablation-based rhythm-control versus rate-control. With the hazard ratio equivalent to the minimal clinically important difference and the result near statistical significance, there is a probable clinically important benefit of ablation-based rhythm-control over rate-control. This RAFT-AF Extend study is to extend follow up in RAFT-AF patients for an additional 24 months in order to have sufficient power to definitely determine if ablation-based rhythm control of atrial fibrillation is superior to rate control for the reduction of the primary outcome of all-cause mortality or heart failure event in patient with atrial fibrillation and heart failure.