Abstract 11684: Comparison of Two Implantable Loop Monitors Implanted in the Same Patient and at the Same Site

Abstract

Introduction: Implantable loop recorders (ILR) are utilized for diagnosis of AF and evaluation of syncope. The diagnosis of AF is based mainly on RR variability. Under sensing and Oversensing with these ILRs is being reported in a separate retrospective analysis. In this study we compared the real time & recorded Electrogram characteristics obtained with two ILRs in the same patient at the same site Hypothesis: The amplitude of the R wave & clarity of P wave would enable the correct diagnosis of a recorded event & minimize under sensing and oversensing. This would thereby increase the specificity and sensitivity of the diagnosis of AF & asystole. Methods: The two ILRs were the Medtronic REVEAL LINQ I and the BioMonitor III device. The Biomonitor is 77.5mm x8.6 mm x4.4 vs the LINQ I is 44.8x7.2x4 mm. When the Medtronic ILRs reached EOS they were replaced with a BioMonitor III at the same site using the existing pocket. We compared the amplitude of the R wave, presence of a clear P wave at the time of implant, undersensing and oversensing of recorded events. Results: 30 consecutive patients were included in the study. 17 Male and 13 Female Mean age was 70.3 + 8 yrs. Mean BMI was 28.4 + 5.05. Indication for implantation was AF management in 23 and syncope in 7. The mean R wave was 0.35 + 0.2 mv with the Reveal as compared to 0.98 + 0.4 with the BioMonitor III, ( p=0.001 ).P wave in sinus rhythm was present in 19/30 with the Reveal vs 28/30 of the BioMonitor III implants (P=0.004).Undersensing of events was seen in 5/ 30 patients with the Reveal vs 5/30 with the BioMonitor III (p>0.1), Oversensing was seen in 4/30 with the reveals vs 0/30 with the BioMonitor III P>0.1(p=0.12). The amplitude of the R wave and the presence of a clear P wave had a negative correlation with the BMI R =(-0.2) ). A clear P wave when present confirmed an AF episode as labelled by the device /mechanism of tachycardia and type of block in both loop monitor’s Conclusions: 1.R wave was significantly greater with the BioMonitor III (greater surface area) than a Reveal LINQ. 2. A clear P wave was more often present in sinus rhythm with a BioMonitor III 3. BMI had a negative correlation with both the amplitude of R wave and the presence of a clear P wave with both ILRs. 4. A clear P wave in the recordings significantly impacts the confirmation of an AF episode