Investigation of the Utility of the Audible Alert in Recent Generation Medtronic Implantable Cardioverter Defibrillators.

BACKGROUND: Medtronic implantable cardioverter defibrillators (ICDs; Medtronic Inc., Mounds View, MN, USA) are equipped with Patient Alert™, a feature in which the ICD generator emits a series of audible tones to notify patients of possible system malfunction. A prior study of this issue revealed that only 50% of patients with older Medtronic devices were able to hear alerts. More recently, Medtronic has incorporated modifications to the alert. Therefore, we studied how frequently alert tones emitted by the current generation of Medtronic ICDs are audible by patients.

METHODS: A series of patients were evaluated in an outpatient ICD clinic. Alert tones were demonstrated using a device programmer in a quiet room and in the presence of low-level background noise. Patients reported whether they heard the tones, and they completed questionnaires regarding the tones.

RESULTS: The total sample size was 100 patients, 81 male, who ranged from 29 years to 94 years of age (mean age 72.1 ± 11.8). Among the study subjects, 46% were older than 75 years, 41% were between 55 years and 75 years, and 13% were younger than 55 years. In the absence of background noise, 94% of patients were able to hear both alerts, 1% heard only one alert, and 5% heard neither. In the presence of background noise, 88% of patients heard both the alerts, 7% heard only one alert, and 5% heard neither alerts.

CONCLUSIONS: Our results demonstrate that alert tones in recent generation Medtronic ICDs have improved audibility, compared to prior published data, among a large outpatient ICD population.