Remote Cardiac Monitoring of Higher-Risk Emergency Department Syncope Patients After Discharge - A Pilot Study

Syncope is a sudden transient loss of consciousness followed by spontaneous complete recovery; it is a very common problem and can be a precursor to sudden death. This study will increase the early identification of patients with serious underlying arrhythmia by combining our Canadian Syncope Risk Score (CSRS) with innovative remote (out-of-hospital) monitoring technology. Approximately 2-3% of ED syncope patients will suffer arrhythmia or die from unknown causes within 30 days of ED disposition (in-patient or outside the hospital). It is the concern for occult arrhythmia and its associated mortality that leads to prolonged cardiac monitoring in the ED, observation units, or by hospitalization; and wide variations in investigations and hospitalization. New and innovative technology has made remote monitoring feasible for prolonged periods (15-30 days) and is reliable. This technology allows arrhythmias to be transmitted live to a central monitoring station automatically based on the device algorithm or by the touch of a button when patients are symptomatic. However, the lack of tools to identify those at risk has limited the use of this new technology to improve patient outcomes. The CSRS tool, developed to predict the 30-day risk of arrhythmia/death showed that higher-risk (score ≥3) patients have a 17.2% observed risk of arrhythmia/death within 15 days. The aim of this randomized controlled trial (RCT) is to compare the diagnostic yield of a 15-day event monitor to a 48-hour Holter monitor (usual care) among higher-risk syncope patients discharged home at 10 Canadian EDs.

Context: Currently, only Holter monitoring (records all cardiac beats) for 1-2 days is used and prolonged monitoring devices are not used for arrhythmia detection. The majority of syncope patients are not monitored when symptomatic. Arrhythmias are detected only if evident when patients seek care. The investigators recently completed a multicenter prospective syncope study and developed the CSRS. Our results show that most serious conditions are identified within the first few hours in ED among low and moderate-risk patients while for non-low-risk patients the risk of arrhythmia remains high up to 15 days indicating the need for prolonged monitoring.

Previous studies and Rationale: A small randomized study with the old technology that required patient activation for arrhythmia capture found higher diagnostic yield than Holter, but the utility was limited due to patients' inability to activate the device after symptoms. Two small studies of unselected syncope patients, one prospective (n=48) and another registry analysis (n=92) found a diagnostic yield of 30 - 38% with prolonged monitoring for 7-33 days. The diagnostic yield of Holter is 1-20% based on the risk of enrolled patients. The role of prolonged cardiac monitoring among ED syncope patients has not been well studied. Only Holter monitoring is being currently used, but inconsistently and is applied a few days later. With the technological advances, the investigators hypothesize that 15-day monitoring will lead to higher diagnostic yield than Holter and plan to apply the devices before disposition for high-risk patients discharged home.

Objectives: The primary objective of the REMOSYNC study is to compare diagnostic yield (identification of arrhythmia that requires treatment or exclusion of an arrhythmic cause) for the following two strategies in higher-risk ED syncope patients discharged home from ED: 15-day external cardiac event monitoring (intervention arm) versus 48-hour Holter monitoring (control arm).

Design and Setting: The study will be a multicenter two-arm, double-blinded randomized controlled trial (RCT) comparing two different approaches for detecting serious arrhythmias among high-risk ED syncope patients who are discharged home. Half of the study patients will be randomized to 15-day external cardiac monitoring (intervention group) and the other half will be assigned to 48-hour Holter monitoring (control group and current practice pattern).