Correlation between the electrocardiogram amplitude detected by an implantable cardiac monitor and the implantation depth

Abstract

Abstract Introduction Implantable cardiac monitors (ICMs) primarily use R‐R intervals in subcutaneous electrocardiograms (ECGs) to detect arrhythmias. Therefore, reliable detection of R‐wave amplitude by an ICM is vital. Since ICMs detect subcutaneous ECGs, the impact of the implantation depth should be assessed. Methods and Results This study investigated the influence of ICM depth on R‐wave (ICM‐R) amplitude on an ECG generated by an ICM (JOT Dx; Abbott). Overall, 58 patients who underwent ICM implantation at Kamagaya General Hospital from May 2022 to April 2023 were retrospectively reviewed. The depth‐position was measured using ultrasound imaging after implantation. The depth of the ICM did not show any correlation with ICM‐R amplitude (r = −.0141, p = .294). However, the distance between the ICM and the heart surface showed a significant correlation with ICM‐R amplitude (r = −.581, p < .001). Body weight (r = −.0283, p = .033) and body mass index (r = −.0342, p = .009) were associated with ICM‐R amplitude. S wave in the V1‐lead was also associated with ICM‐R amplitude (r = .481, p < .001). After multivariate analysis, the distance between the ICM and heart surface and the S wave in V1 were independent determinants for the ICM‐R amplitude. Conclusion The ICM‐R amplitude may be higher with the ICM implanted deeper.

Keywords

• amplitude
• depth
• ICM
• ILR
• implantable cardiac monitor
• implantable loop recorder