Factors affecting signal quality in implantable cardiac monitors with long sensing vector.

Electrical artefacts are frequent in implantable cardiac monitors (ICMs). We analyzed the subcutaneous electrogram (sECG) provided by an ICM with a long sensing vector and factors potentially affecting its quality. Consecutive ICM recipients underwent a follow-up where demographics, body mass index (BMI), implant location, and surface ECG were collected. The sECG was then analyzed in terms of R-wave amplitude and P-wave visibility. A total of 84 patients (43% female, median age 68 [58-76] years) were enrolled at 3 sites. ICMs were positioned with intermediate inclination (n = 44, 52%), parallel (n = 35, 43%), or perpendicular (n = 5, 6%) to the sternum. The median R-wave amplitude was 1.10 (0.72-1.48) mV with P waves readily visible in 69.2% (95% confidence interval, CI: 57.8%-79.2%), partially visible in 23.1% [95% CI: 14.3%-34.0%], and never visible in 7.7% [95% CI: 2.9%-16.0%] of patients. Men had higher R-wave amplitudes compared to women (1.40 [0.96-1.80] mV vs 1.00 [0.60-1.20] mV, In ordinary clinical practice, ICMs with long sensing vector provided median R-wave amplitude above 1 mV and reliable P-wave visibility of nearly 70%, regardless of the position of the device. Women and obese patients showed lower but still very good signal quality.

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© 2021 The Authors. Journal of Arrhythmia published by John Wiley & Sons Australia, Ltd on behalf of Japanese Heart Rhythm Society.

Déclaration de conflit d'intérêts

Daniele Giacopelli is employee of BIOTRONIK Italia. All the other authors have no conflicts relevant to the contents of this study to disclose.