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Abstract 272: Sensitivity of Conventional Monitoring Strategies to Diagnose Patients With Pause Arrhythmias Relative to Insertable Cardiac Monitors


 Background:
 Diagnosing cardiac pauses that could produce syncopal episodes is clinically important to guide appropriate therapy. However, the infrequent nature of these episodes can make their detection a challenge with conventional monitoring (CM) strategies with short-term ECG monitors. We simulated several CM strategies and analyzed the sensitivity to diagnose patients with pause arrhythmias compared to continuous monitoring with an insertable cardiac monitor (ICM).
 
 
 Methods:
 CM was simulated from syncope patients’ ICM data by assuming the 1st detected true pause episode (≥5s) was symptomatic and prompted further evaluation. Based on published literature, 32% of patients were assumed to be admitted for 3 days of inpatient monitoring followed by CM of varying durations (24 or 48 hrs, and 14, 30 or 60 days) beginning at random within the next week; the other 68% were assumed to be discharged home, with CM of varying durations beginning at random within the next week. Subsequent true pause episodes in patients remaining undiagnosed with CM triggered additional rounds of CM, with simulations repeated 1,000 times. Longer pause definitions of ≥6-8s were also evaluated. ECG diagnosis was considered successful if a pause episode occurred simultaneous to CM.
 
 
 Results:
 A total of 105 true pause episodes from 44 patients (mean±SD age 66±17, 48% male) were detected by ICM, during 505±333 days of continuous follow-up. Patients experienced an average of 2.4±2.7 pause episodes ≥5s during follow-up. Relative to ICM-diagnosed patients, the mean sensitivity of CM to capture an ECG diagnosis for these pause episodes during follow-up ranged from 13.8% (on average, 6.1 of 44 patients) with 24-hr holter to 30.2% with two 30-day monitors (13.3 of 44 patients) (Figure). Sensitivity further decreased for pause durations of ≥6-8s, due to the less frequent occurrence of these episodes and consequently lower likelihood of capture with CM. Average days of follow-up without a diagnosis was 109 days with ICM versus a range of 384-452 days with CM modalities.
 
 
 Conclusion:
 Of syncope patients diagnosed with pause arrhythmias via ICM, the vast majority would go undiagnosed via CM strategies and therefore may not be optimally managed for syncope prevention. The cost-effectiveness of these strategies requires further study.
 
 
 
