REveAL™ and CARElink™ (Real Care): Minimising the time taken to achieve a diagnosis in the implantable loop recorder population

Abstract

Introduction

Syncope accounts for ≈ 2.7/1000 population/year of presentations to UK healthcare, a figure believed to be underestimated by up to 30% due to misdiagnosis. For some patients the cause of their episode/s may remain unexplained.

The implantable loop recorder (ILR) is effective for diagnosis of syncope and palpitations, with UK and European guidelines advising its use if symptoms are infrequent. However current follow-up regimes can lead to a slow diagnostic pathway for patients. Remote monitoring technology allows patients to send their ILR data to their clinic

Research Questions

1) Does remote monitoring of ILRs reduce time to diagnosis and/or increase diagnostic yield?

2) What is the impact of remote monitoring on logged events requiring analysis?

Method

New ILR patients at a single implanting centre were recruited. Following informed consent, they were randomised into control or experimental groups. Patients in the control group were reviewed in the conventional manner with routine 6 monthly follow-ups plus additional ad hoc checks if symptoms occurred. Patients in the experimental group were asked to send transmissions fortnightly or following a symptom.

All recordings were reviewed and classified as true or false events according to pre-defined criteria. Significant true event ECGs were reviewed blindly by a cardiologist. All data were verified by two physiologists or a physiologist and a cardiologist prior to analysis. The primary outcome variable was median time to clinical diagnosis.

Results

37 patients were randomised, 19 to the control and 18 to the experimental group. The control group comprised 11 males and 8 females with a median age of 60 (36-86) years. The experimental group comprised 10 males and 8 females, median age 58 (36-84) years. Mann-Whitney U testing showed no significant differences in group demographics.

Following randomisation 5526 events were logged, 1264 in the control and 4262 in the experimental group. 28 (76%) of patients had a true event, which led to a diagnosis in 23 (67%) of patients. There were 13 patients with true events and 10 diagnoses in the experimental group, with 15 true events and 13 diagnoses in the control group. Asystole was the most common event that led to a diagnosis, accounting for 35% of diagnoses.

Kaplan-Meier analysis was used to assess the primary outcomes of time from event to follow-up, and time to clinical diagnosis. Compared to the control group, the median time from event to follow-up was reduced from 3 to 1 week (p=0.004). Median time to diagnosis was reduced from 13 to 6 weeks (p=0.049) when remote monitoring was used.

Conclusion

In patients with ILR, remote monitoring significantly reduced diagnostic delay although the overall diagnostic yield was not increased. However remote monitoring resulted in a three-fold increase in logged events that required analysis with only 1 in 328 proving to be true events: this will have significant resource implications.