The Role of Electrophysiology Testing in Survivors of Unexplained Cardiac Arrest

Study Overview
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Brief Summary
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Sudden cardiac death (SCD) remains a major cause of mortality within developed nations despite aggressive efforts to reduce its societal burden. Despite extensive clinical and genetic investigations, a subgroup of cardiac arrests remain unexplained, highlighting the potential contribution of additional cardiac conditions that may not be identified with contemporary diagnostic algorithms. The EPS ARREST study aims to evaluate the role of invasive electrophysiology study within this patient population.

Detailed Description
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The majority of cases of SCD in older individuals occur secondary to coronary and structural heart disease, while genetic channelopathies and cardiomyopathies are prominent contributors in young adults. Among individuals that suffer aborted cardiac arrests in the absence of overt coronary and structural heart disease, diagnostic algorithms that screen for cardiac channelopathies and more subtle forms of structural heart disease have been established. Despite the extensive investigations currently utilized, a significant proportion of aborted cardiac arrests remain unexplained. Although invasive electrophysiology studies are a cornerstone for diagnosis and management of arrhythmia disorders, they are not invariably included in the workup of cases of unexplained aborted cardiac arrest. This is largely driven by initial studies suggesting that the diagnostic yield in this context is low, however these investigations often used invasive electrophysiology studies indiscriminately in all cases of aborted cardiac arrest. Since these earlier studies, our insight and approach to SCD has evolved and it has become clear that the majority of patients do not require an invasive electrophysiology study for diagnosis. However an invasive electrophysiology study may still have an important role among these individuals when the initial workup is negative. Notably, arrhythmias that require invasive electrophysiology for diagnosis, including bundle branch reentrant ventricular tachycardia and supraventricular tachycardias associated with hemodynamic collapse, have been identified as arrhythmic culprits in this patient population. The goal of the EPS ARREST study is to evaluate the diagnostic yield of a standardized invasive electrophysiology study among survivors of SCD when initial investigations fail to identify an underlying etiology.

Official Title
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The Role of Electrophysiology Testing in Survivors of Unexplained Cardiac Arrest

Conditions
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Sudden Cardiac Death

Intervention / Treatment
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* Procedure: Invasive Electrophysiology Study


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Unexplained cardiac arrest requiring cardioversion or defibrillation Willing and able to sign informed consent Exclusion Criteria: Coronary artery disease (stenosis > 50%) and clinical findings consistent with an ischemic arrest Reduced left ventricular function (left ventricular ejection fraction < 50%) on echocardiogram or cardiac MRI. Persistent resting QTc > 460 msec for males and 480 msec for females Resting QTc < 350 msec Type I Brugada ECG with >/= 2 mm ST elevation in V1 and/or V2 (Spontaneous or Drug-Induced) Polymorphic or bidirectional ventricular tachycardia observed with exertion on exercise treadmill testing Clinical, electrocardiographic, and/or imaging findings consistent with a diagnosis of arrhythmogenic right ventricular cardiomyopathy Myocarditis Reversible cause of cardiac arrest such as marked hypokalemia (<2.8 mmol/l) or drug overdose sufficient in severity without other cause to explain the cardiac arrest. Arrhythmic mitral valve prolapse syndrome Documented ventricular fibrillation initiated by a short-coupled premature ventricular contraction
Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Unexplained Aborted Cardiac Arrest<br>Survivors of sudden cardiac death with no identifiable etiology following initial diagnostic workup. | Procedure: Invasive Electrophysiology Study<br>* Invasive electrophysiology studies will be performed using four catheters placed in the right ventricular apex, the coronary sinus, the His bundle region, and the high right atrium. Standard induction protocols for supraventricular and ventricular arrhythmias will be utilized in the absence and presence of isoproterenol. Long-short ventricular extra-stimuli will also be delivered to screen for bundle branch reentrant ventricular tachycardia. The study is considered observational as the participating sites perform electrophysiology studies in this patient population as part of standard clinical care.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Arrhythmic culprit for aborted cardiac arrest | Identification of an arrhythmic culprit for aborted cardiac arrest using an invasive electrophysiology study. | Assessed immediately upon testing | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Prevalence of bundle branch reentrant ventricular tachycardia | Prevalence of bundle branch reentrant ventricular tachycardia among survivors of unexplained cardiac arrest. | Assessed immediately upon testing | 
| Prevalence of supraventricular tachycardia associated with hemodynamic collapse | Prevalence of inducible supraventricular tachycardia during invasive electrophysiology study among survivors of unexplained cardiac arrest. | Assessed immediately upon testing | 
| Prevalence of a latent/cryptic accessory pathway | Prevalence of a latent/cryptic accessory pathway among survivors of unexplained cardiac arrest. | Assessed immediately upon testing. | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Sudden Cardiac Death, Cardiac Arrhythmia, Electrophysiology Study, Genetics