Review of Remote Cardiac Implanted Electronic Device Interrogation Used in a Hospital Setting

Abstract. Background. Remote interrogation of cardiac implantable electronic devices (CIED) has been available for hospitals but not widely used. Objectives. The purpose of this study was to identify actionable events, measure time from transmission to analysis, and determine ease of use after remote CIED interrogation. Methods. We reviewed CareLink Express (Medtronic) transmissions from subjects with heart failure, syncope, and stroke. Time from transmission to analysis by a local Medtronic representative was collected. A Likert-type questionnaire was given to staff nurses to evaluate ease of use. Results. Over 12 months, 102 transmissions were collected from 47 heart failure, 45 syncope, and 10 stroke subjects. Mean age was 77 years, with 56% male. In total, 40% of heart failure subjects had new or poorly controlled atrial fibrillation (AFib) 30 days prior to admission. In subjects with syncope, 13% had stored events that corresponded with the syncopal event. New AFib was found in 22% of stroke subjects. Only 8% of subjects required additional in-person interrogation or programming. The average time from transmission to analysis was 29 minutes. Nurses (n=19) reported CareLink Express to be very easy to use 95% of the time. Conclusion. CIED remote interrogation with CareLink Express is efficient and very easy to use. Events can be quickly identified, with only 8% requiring in-person interrogation or programming. Remote interrogation should be considered for hospital patients being evaluated for heart failure, syncope, and stroke, with AFib the most frequent finding. 

Key words: CIED, remote monitoring, atrial fibrillation, heart failure, stroke, syncope

Background

Placement of cardiac implantable electronic devices (CIEDs), including pacemakers, implantable cardioverter-defibrillators (ICDs), and loop recorders, has steeply risen over the past several years.^1-3 Remote interrogation and monitoring is supported by established guidelines for use at home. The current workflow for hospital interrogations of CIEDs requires waiting for trained personnel or a manufacturer’s representative to interrogate the device with a programmer at the bedside in the emergency department or hospital unit.

We recently described a nurse-managed remote CIED interrogation program for hospital patients, including personnel training and an algorithm for the new workflow and reporting of results.⁴ Manufacturers have developed technology for remote interrogation of CIEDs for hospital use. This standalone equipment can interrogate a patient’s device via a wand placed over the CIED with simple instructions. The system can only read data; it cannot reprogram or change any functions. The CIED can be interrogated by any trained medical personnel. It does not require specific training in devices or electrophysiology. Data obtained from the CIED is transmitted securely through the remote interrogation device to the specific manufacturer’s representative for interpretation. Findings are reported to healthcare professionals via phone call, fax, and/or secure email. The final report is also available on the remote monitoring website provided that the patient is currently enrolled in the platform. 

Research demonstrates that hospital remote interrogations provide an efficient and cost-effective alternative to traditional CIED interrogation.^5-9 Time to interpretation of the interrogation has been reported as low as 15-45 minutes.^5-8 Patients needing immediate in-person interrogation or programming has been reported to be <10%.^5,8,9 Despite these positive outcomes, this technology has been slow to be adopted in hospitals. 

Literature is lacking on use of hospital remote interrogation of CIEDs in patients with heart failure, syncope, or stroke. The purpose of this study was to identify actionable events, measure time from transmission to analysis, and determine ease of use by telemetry staff nurses in subjects with heart failure, syncope, and stroke. 

Methods

The study was a prospective, single-center observational study approved by the Edward-Elmhurst Institutional Review Board (clinicaltrials.gov NCT03338946). The enrollment period was from April 2018 to April 2019. Subjects admitted with heart failure, syncope, or stroke who had their Medtronic CIED interrogated using CareLink Express (Medtronic) were enrolled.

The CareLink Express platform and service is a remote interrogation system that enables clinicians to obtain data regarding the status of CIEDs. This system was deployed at the hospital, and cardiac telemetry staff nurses were trained on use of CareLink Express. If a CIED interrogation was requested, the telemetry unit charge nurse performed the interrogation and notified the Medtronic representative. A callback number was provided to the local representative so they could directly call the ordering healthcare professional with results. The study protocol followed these standard of care procedures.

The following variables were captured: demographics, CIED indication, ejection fraction (EF), reason for admission, time of interrogation, and resulting analysis from CareLink Express. Device parameters, stored arrhythmic events or therapies, battery longevity, most recent intrinsic amplitude, lead impedance, and auto capture thresholds were reviewed by industry representatives. If a subject required additional in-person interrogation or programming after the remote interrogation, the reason for the interrogation or programming changes was collected. For subjects with heart failure, we identified any new or increased AFib. This was defined as AFib with an average ventricular rate of >100 bpm and/or AFib duration ≥6 hours/day within 30 days prior to interrogation. Percentage of cardiac resynchronization therapy (CRT) pacing in those with CRT devices was collected. 

For subjects evaluated for syncope, we looked at stored events that corresponded with the syncopal event along with sensing, lead impedance, and auto thresholds. For subjects with suspected stroke, we specifically looked at any AFib episodes and duration.

Ease of use by staff was assessed with an anonymous Likert-type questionnaire given to telemetry staff nurses who were trained on the use of CareLink Express. They had no prior training in devices or electrophysiology. Responses to survey questions included: 1 = “very easy”, 2 = “easy”, 3 = “difficult”, and 4 = “very difficult.” Survey data was gathered during the study period.

Results

There was a total of 102 subjects enrolled: 47 with heart failure, 45 with syncope, and 10 with stroke. Demographics, CIED type, and EF are described in Table 1. Actionable events are listed in Table 2. 

There were 47 heart failure subjects, 18 of which had CRT devices. Of the 18 CRT subjects, 4 (22%) had less than 90% CRT pacing. All four of these subjects had poorly controlled AFib. New or increased AFib was identified in 19 (40%) of subjects.

There were 45 subjects evaluated for syncope; 16 subjects had an ICD, 24 subjects had a pacemaker, and 5 subjects had an insertable cardiac monitor (Reveal LINQ ICM; Medtronic). Four ICD subjects had ventricular tachycardia (VT) / ventricular fibrillation (VF) with appropriate ICD therapies that correlated with the syncopal event. One pacemaker subject had AFib with rapid ventricular response that correlated with the syncopal event. One ICM subject had significant bradycardia that correlated with the syncopal event. Of the 40 subjects with pacemakers/ICDs, 39 had stable capture thresholds and 1 had auto thresholds programmed off. This was a single-chamber ICD implanted for hypertrophic cardiomyopathy with 0% pacing since implant. All subjects had stable lead impedance and R wave sensing. Three subjects who were pacemaker dependent could not have R waves evaluated.

There were 10 subjects evaluated for TIA/stroke. One subject had no atrial lead, so AFib could not be collected. Two subjects (22%) had new or recurrent AFib, warranting initiation of anticoagulation. 

There were only 8 subjects who required in-person interrogation or programming after remote review. The reasons for additional interrogation or programming were: (1) to look more closely at atrial lead diagnostics; (2) to determine pacemaker dependence; (3) to get prior history after one patient who had just been interrogated; and (4) to reprogram — one for VT/VF therapies, and one for pacing therapies.

We were able to collect time from transmission to analysis on 97 subjects. The average time from transmission to analysis was 29 minutes, which was measured as the transmission time listed on the interrogation report to the time that the analysis was reported to the requesting healthcare provider.

Ease of use of CareLink Express was assessed with a Likert-type scale ranging from 1 (very easy) to 4 (very difficult). Of the 19 charge nurses who responded, 95% (n=18) indicated that the system was very easy to use, and 5% (n=1) indicated that it was easy to use. No nurses reported that it was either difficult or very difficult to use.    

Discussion

Actionable Events

In this observational study, we were able to evaluate 102 subjects with heart failure, syncope, or stroke using the CareLink Express remote CIED interrogation system. The most impressive finding was that 40% of subjects admitted with heart failure had new or poorly controlled AFib within 30 days of admission (time of interrogation). Our findings are similar to those previously reported with the prevalence of AFib in patients with heart failure >30%.¹⁰ AFib is a known contributing factor to heart failure admissions.¹⁰ AFib and heart failure are increasing, so routine use of hospital remote interrogation may improve evaluation and management upon admission. An additional finding was that only 4 heart failure subjects had <90% CRT pacing, but all 4 subjects had poorly controlled AFib. This finding warrants further exploration. 

There were few subjects with stroke seen during the enrollment period; however, 22% had newly diagnosed AFib. We surmise that most subjects were followed remotely as an outpatient and any new episodes of AFib would have been identified with patients started on anticoagulation as an outpatient.

As expected, several subjects had a stored arrhythmic event associated with the syncopal event. Remote interrogation relies on auto thresholds, which are typically done overnight. No subjects had out-of-range auto thresholds. One subject with hypertrophic cardiomyopathy (HCM) had 0% pacing whose auto threshold was not programmed on. It would be unlikely this event was related to changes in thresholds. Quick identification of arrhythmias (or lack of arrhythmias) that may have contributed to a syncopal event helps direct evaluation and management.

Immediate CIED Reprogramming

An additional important finding was that only 8% required immediate in-person interrogation or reprogramming, which is consistent with previous studies.^5,8,9 If many devices required immediate in-person interrogation or reprogramming, there would be no benefit to remote interrogation. As 92% did not require additional programming, the benefit of remote interrogation is clear. 

Time

Although we did not use a comparison group, Ahmed et al previously reported time from interrogation to analysis as high as 127 minutes.⁶ Our reported average of 29 minutes reduces this time by 77%, from the reported 2 hours to an average of roughly 30 minutes.

Ease of Use

The CareLink Express platform was found to be very accessible, as nurses with no prior device training were willing and able to perform remote interrogations. The most important piece was ensuring that the correct provider received the final interpretation. Although nurses were eager and willing to perform the interrogation, the final interpretation details would typically be beyond their expertise. The final interpretation was reported back to the healthcare professional requesting the interrogation (eg, the ED physician, cardiologist, or nurse practitioner).

Conclusion

In summary, remote CIED interrogations are an efficient alternative to in-person interrogation for evaluation of subjects with heart failure, syncope, or stroke. The CareLink Express was considered to be very easy to use by staff nurses. Finally, the need for immediate, in-person CIED programming was infrequent (only 8%) in this study. 

Limitations

This was a single-center study with a small sample size, but it provides a basis for further research.

Acknowledgements 

Funding for this study was provided by Medtronic from the investigator-initiated research grant program. We thank Justin Mao, MD for manuscript review. 

Disclosures: Funding for this study was provided by Medtronic from the investigator-initiated research grant program. Ms. Gifford reports she is part of the allied professional advisory board for Medtronic and Boston Scientific. Ms. Larimer reports she is an employee of PhysIQ. Ms. Blalock has nothing to disclose.

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