Diagnostic evaluation of implantable loop recorder devices associated with remote monitoring: a retrospective multicentric study

Abstract

Abstract Funding Acknowledgements Type of funding sources: None. It has been proven that Implantable Loop Recorders (ILRs) and remote monitoring could improve diagnostic rate, shorten time-to-diagnosis and thus better patient’s clinical outcome. Medical indications to ILRs have been lately extended, and many technical improvements have been achieved in the last few years. Nowadays many different ILRs are available, therefore choosing the best device, according to the patient’s clinical features, could help to reach an optimal patient management. Aim of this retrospective multicentric study is to compare which is best between 2nd generation ILR Medtronic Reveal™ LINQ (MRL) or St. Jude Medical Confirm™ RX (SCX), both associated with remote monitoring, in terms of overall accuracy rate (OAR), true positive detection rate (TPDR) and arrhythmias-free survival (AFS). Patients included in the study required an ILR implant for syncope, non-recurring heartbeat, suspect AF, Brugada Syndrome, post-ablation AF monitoring and non-stustained ventricular tachycardia. Medtronic Reveal™ LINQ (n=436, mean age 66±15, mean BMI 30±5) and St. Jude Medical Confirm™ RX (n=98, mean age 64±14, BMI 27.5±4) implanted patients underwent a weekly remote and a six-monthly outpatient follow-up. Every transmission was judged by two different cardiologists. The final diagnosis was set only in case of agreement, conversely, the transmission was discussed either considered non-diagnostic. Patients were studied for atrial fibrillation (AF), pauses (Ps), bradycardias (Bs) and tachycardias (Ts). MRL transmitted 5585 times, SCX 7545 (monthly transmission/patient ratio 25.5±45.6 vs 0.9±1.1 respectively). MRL had statistically significant better OAR for AF (61% vs 14%, p<0,001), Ps (20% vs 7%, p<0.001) and Bs (72% vs 20%, p<0.001). SCX had statistically better OAR for Ts (84% vs 56%, p<0.001). MRL had statistically significant better TPDR for AF alone (82% vs 48%, p<0.001) and non-statistically significant better TPDR for Ps (32% vs 28%, p=0.117), Bs (48% vs 38%, p=0.133) and Ts (69% vs 69%, p=0.505). Patient with MRL had better AFS at a six-months follow-up (72% vs 20%, p<0.001). The overall accuracy rate for every arrhythmic episode was better in MRL implanted patients than in the SCX implanted ones (43% vs 16%, p=0.001). Transmission rate was higher in SCX, even though MRL had a better accuracy in detecting real arrhythmic events. The overall accuracy rate of arrhythmic events in both groups is sub-optimal, therefore further engineering research is required to improve diagnostic accuracy of ILRs.