Long-Term Stability and Clinical Utility of Amplified Atrial Electrograms in a Single-Lead ICD System with Floating Atrial Electrodes.

BACKGROUND

Available atrial electrograms in implantable cardioverter defibrillators (ICDs) improve arrhythmia diagnosis, allow monitoring for atrial fibrillation, and may reduce the risk of inappropriate therapies. A recently introduced ICD system using a single-lead with floating atrial electrodes provides diagnostic capability of a dual-chamber system without placing an additional lead. Data on long-term clinical performance of this system are limited.

METHODS

We retrospectively analyzed data from 35 consecutive patients implanted with Biotronik VR-T DX devices and Linox DX leads. (Biotronik, SE & Co., Berlin, Germany) RESULTS: Of 35 patients (77% male, age 52 ± 11.28 years), 32 were followed for a mean of 432 ± 197 days (range 56-765). During implantation, average preamplified and amplified sinus P-wave amplitudes were 2.61 ± 1.39 mV (range 0.9-6.8 mV) and 8.7 ± 4.51 mV (range 1.4-18 mV), respectively. Despite statistically significant variations, the amplified P-wave amplitude measurements (calculated mean values over 3 months) remained within a clinically acceptable range during follow-up (5.4-8.7 mV). R-wave amplitude and ventricular pacing threshold measurements were stable over time. A total of 13 stored arrhythmia events (three ventricular tachycardia, eight supraventricular tachycardia, two atrial fibrillation) were reviewed. All of them showed readily interpretable atrial electrograms. Eight out of 10 (80%) supraventricular events were correctly classified by the device. Three patients received inappropriate ICD therapies.

CONCLUSION

The single-lead ICD system using a floating atrial dipole provides reliable recording of atrial signals during sinus rhythm and arrhythmias. Our data suggest that the system may offer diagnostic advantages of a dual-chamber device without potential risks of an additional atrial lead.