Same-day discovery of implantable cardioverter defibrillator dysfunction in the TRUST remote monitoring trial: influence of contrasting messaging systems

Abstract

Aims: Assess whether automatic remote home monitoring (HM) permits same-day evaluation of implantable cardioverter defibrillator (ICD) system dysfunction.

Methods and results: Compromised ICD system integrity (generator/lead) demands prompt evaluation. Home monitoring promises earlier discovery but may be limited by technological differences and follow-up mechanism. We tested whether HM enabled event review within 24 h, and contrasted differing messaging mechanisms. Nine hundred and eight patients in the TRUST prospective multicentre trial were followed by HM for 15 months. ICD system problems automatically triggered notifications: repeatedly ('redundant') for impedance deviations and elective replacement indication (ERI), but only a single transmission for '30 J ineffective'. Detection time from event onset to physician evaluation was measured. Forty-three system-related alerts occurred; 42% were asymptomatic, 42% were actionable, and 22 of 43 (51%) were viewed within 24 h. Redundant notifications were: 1 ERI, 9 shock impedance, 2 ventricular and 6 atrial pacing impedance. Most (11/18; 61%) were detected in <24 h. Others elicited daily notifications without interruption until resolution. For single transmissions, 11 of 25 (44%) events were detected on the same day. Most (56%, 14/25) were detected between 1 and 39 days (mean 10.0 ± 13.0 days). Ten of 14 events were detected by HM and 4 at the time of office visits. These observations suggest single transmissions were vulnerable to detection failure. Mean detection time of redundant events was 1.1 ± 1.8 vs. single transmission 5.6 ± 10.9 days (P = 0.05). Hence, redundant notification avoided late detection.

Conclusion: Same-day discovery of ICD dysfunction, even if asymptomatic, was achievable. For those events not evaluated within 24 h, repetitive messaging promoted earlier discovery. Reorganization of clinical follow-up methods may maintain early reaction ability.

Trial registration: ClinicalTrials.gov NCT00336284.

Figures

Figure 1

Events.

Figure 2

Days to detection of ICD problems in patients assigned to remote HM. Overall, 22 of 43 (51%) were detected within 24 h.

Figure 3

Example of redundant messaging following ventricular lead fracture in patient with ICD implanted for secondary prevention. Top event notification flagged (red exclamation mark on yellow background) for out of range ventricular lead impedance. The lead impedance trend (below) had been stable, (black dots) but then suddenly increased during sleep (2.52 am) promptly triggering an event notification (red dot on trend). The patient was unaware of this critical device integrity failure which occurred 7 days after a normal conventional check at an office visit (marked FU 8/28/2007). The patient was called immediately the same day (FU 9/5/2007), and lead replacement scheduled. System continued to transmit daily in the interim – a total of 8 redundant messages were sent until problem resolution, i.e. lead replacement and defibrillation threshold testing (marked VF event notification) with return of impedance to normal range (9/15/2007). With a conventional ICD, the issue may have remained unidentified until next device check 1 year later, putting patient at risk, but in this case automatic remote monitoring enabled same-day physician evaluation.

Figure 4

Summary data according to messaging method in patients assigned to remote HM. Days to the detection of ICD problems are contrasted between repeating (redundant) vs. single alerts. The majority (11/18) of redundant events were detected within 24 h (e.g. Figure 3). Single alerts were usually reviewed late.