Abstract 13134: Comparative Analysis of Implantable Loop Recorder Devices

Implantable loop recorders ILR are used for diagnosis and evaluation of Atrial fibrillation and Syncope. The devices mainly utilize RR variability to determine an episode of AF.Diagnosis of bradycardia is based on rate and absence of any R wave. Presence of a P wave is not a prerequisite.In this Retrospective study we used recorded electrogram characteristics obtained with two ILRs. Hypothesis-The R wave amplitude and clarity of P wave facilitates correct diagnosis of AF and any heart block .This would also infuence any undersensing and oversensing Methods-The two ILRs were Medtronic Reveal I & Biomonitor III.The Biomonitor is 77.5x8.6 x4.4 mm whereas LINQ I is 44.8x7.2x4 mm. Main difference in the two is that BioMonitor III has larger sensing area ( 77.5 vs 44.8). Results 106 patients were included in this analysis 53 patients had Medtronic Reveal I and the remaining 53 patients had a BioMonitor III. We compared the amplitude of the R wave, presence of P wave, Undersensing and Oversensing of recorded events. Group I = patients who had Medtronic reveal I, 19 Males, 34 Females, mean age 74+11 BMI=28.83±6.8 Indication was AF in 38 & syncope in 15. Mean R wave was 0.48 mV±0.38, Clear P waves were noted in 16/53. Oversensing noted in 8/53, Undersensing in 4/53. Group I I = patients with BioMonitor III 27 Males, 26 Females,Mean age 73+10 Mean BMI 29.20±5.35. Indication was AF in 37 & syncope in 16.Mean R wave was 0.65 mV±0.37. Clear P waves noted in 33/53. Oversensing noted in 8/53, Undersensing in 0/53. Group II( BM III) had significantly greater R wave amplitude (p=0.02), the presence of a P wave in sinus rhythm was in significanly greater number of patients (p=0.009) There was no significant difference in proportion of patients with oversensing in the two groups ( p=0.09 ) However undersensing was seen in significanly less No of patients in Group II as compared to Group I ( p= 0.04). The two groups are matched for age sex, BMI , indication for implantation. Conclusions 1 In ILRs the recordings obtained with a Biomonitor III ( larger recording area ) had significantly greater amplitude of R wave and a greater proportion of patients with a clear P wave as compared to a Medtronic Reveal 1 ILR 2. Undersensing is also less seen with the Biomonitor ILR which may be related to the R wave amplitude.