December 04, 2018
2 min read

Variations in time delays prominent among remote monitoring systems in ICDs

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Among implantable cardioverter defibrillators with remote monitoring systems, there are significant differences in time delay from event detection to acknowledgement by hospital staff, according to a study published in HeartRhythm.

“It is generally agreed that [remote monitoring] should not replace an emergency service, but in combination with in-clinical follow-up it enables faster detection of clinical events and reduces in-clinical visits,” Malene Söth-Hansen, MS, of the department of cardiology at Aarhus University Hospital in Denmark, and colleagues wrote. “Our findings add new and robust knowledge about differences between four currently available [remote monitoring] systems and are consistent with previous reports.”

Danish registry data

Researchers analyzed data from 3,472 events from 1,802 patients with ICDs with or without cardiac resynchronization therapy with a wireless remote monitoring system. Information was collected from the Danish ICD Registry and the National Danish Patient Registry. Other data were collected from remote monitoring web pages, which included information on remote monitoring transmissions, device-related data and events.

The four remote monitoring systems included in this study were CareLink Network (Medtronic; n = 468; mean age, 66 years; 77% men), Home Monitoring (Biotronik; n = 374; mean age, 70 years; 81% men), (St. Jude Medical; n = 764; mean age, 67 years; 78% men) and Latitude Patient Management (Boston Scientific; n = 196; mean age, 63 years; 82% men).

Patients were followed from September 2014 or at the time of ICD implantation, whichever occurred latest. Follow-up was conducted until August 2016, death or device explant, whichever occurred first.

The primary outcome was the number of events with a diagnostic delay of less than 24 hours, which was defined as the time between event detection by the ICD and hospital staff acknowledgement.

During a mean follow-up of 730 days, the proportion of events that were acknowledged within 24 hours from detection was 72% for Biotronik, 65% for St. Jude Medical, 23% for Boston Scientific and 18% for Medtronic (P < .001). The median time for diagnostic delay was 13 hours for Biotronik, 18 hours for St. Jude Medical, 163 hours for Medtronic and 222 hours for Boston Scientific (P < .001).

Event acknowledgement

Among events transmitted as alerts by remote monitoring, the percentage acknowledged within 24 hours was 72% for Biotronik, 68% for Boston Scientific, 65% for St. Jude Medical and 61% for Medtronic.


The primary cause of the differences between manufacturers was associated with the time variation for the acknowledgement of ventricular tachycardia (VT) episodes that were not treated with shock therapy, according to the researchers.

“The primary explanation for the discrepancy in diagnostic delay between [remote monitoring] systems observed was huge differences in time to acknowledgment of nonshocked episodes of VT,” Söth-Hansen and colleagues wrote. “Episodes without therapy or treated with [anti-tachycardia pacing] often occur clinically silent or are associated with vague symptoms, but still indicate clinical deterioration. Early detection of such episodes may reduce the risk of shock therapy, which is associated with worse prognosis. Therefore, it can be argued that early detection of nonshocked episodes of VT is as important as early detection of shock delivered for VT/[ventricular fibrillation].” – by Darlene Dobkowski

Disclosures: Söth-Hansen reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.