Background: Pacemaker marker annotations facilitate the interpretation of device behavior in addition to ECG recordings. However, they are only available in conjunction with a programmer. We studied the diagnostic value of a prototype Telemetry Holter Decoder (THD), providing continuous marker annotations on a conventional Holter.
Methods: The study included 20 patients with VDD or DDDR pacemakers. A 24-hour Holter was performed using the THD. Marker annotations are transmitted from the pacemaker to the THD, which transforms them into analog signals, which are recorded on one of the Holter channels.
Results: During a total recording time of 458 hours, high quality marker annotations were retrieved for every patient. Artefacts disturbed the recordings during 184 min (0.67%). The THD provided information not discernible on the ECG: intermittent atrial undersensing during sinus rhythm (1096 times). Atrial tachycardias, not visible on the ECG, were detected in 2 patients. The activation of tachycardia response algorithms was clearly annotated in 11,516 events. A total of 8875 PVC's occurred, 57.8% of which were classified incorrectly in the event counters as conducted or fusion beats. Atrial far-field sensing or VA conduction was demonstrated 4294 times. Electromagnetic interferences, not visible on the ECG, could be seen three times.
Conclusion: Recording of continuous high-quality marker annotation on a conventional Holter is feasible. The THD provides important information on device behavior, even in patients assumed to have regular device function, and shows to be clearly superior to ECG interpretation alone. Such data can be used for improved programming, troubleshooting and for the validation of new algorithms.