What made you decide to do this research? Why was it important to re-evaluate previous findings?
We were somewhat skeptical about the preliminary report presented at Heart Rhythm last May. It received a lot of media coverage, but didn’t have a lot of scientific data. As a large children’s hospital, we see many young patients with pacemakers/ICDs who use iPods and other digital music players, and had not observed any problems. Therefore, we wanted to properly design a study to test this hypothesis.

Describe your study methods. In addition, how long was each individual patient studied?
We prospectively enrolled patients as they came in for their routine clinic visits, and ultimately tested four different models against different pacemaker/ICD brands. A total of 51 patients were enrolled, including both children and adults. Their average age was 22 years (age range 6-60).
The music players tested were the iPod Nano, iPod Video, Microsoft Zune, and Sandisk Sansa. Each was tested for a few minutes at a time, and not over days.

What did your results show?
We found no effect of music players on pacemakers or ICDs. There was frequent interference with the programmers (41%), but this never affected pacing.

How might programmer interference compromise device interrogation? How often do pacemaker and ICD patients generally need to schedule device interrogation, and in your experience, have these patients brought their DMPs with them to appointments?
It would sometimes disrupt communication between the programmer and pacemaker/ICD and just display “electrical noise.” Once the music player was removed a few inches, the interference with the programmer resolved.
Patients typically schedule device interrogations only about 1-3 times per year. They may bring an iPod to testing, but would never have it on top of the pacer during testing, so it is not an issue.

Also, twenty-six patients (53%) who experienced interference with telemetry programmer communication used the same manufacturer’s device. Is this higher incidence statistically significant?
I don’t think this is a significant difference by manufacturer. It is too small a number to be sure.

How do your findings compare with other DMP-related research? How do you explain any difference in findings? Could patient age range be a possible factor?
Thaker and colleagues² have a new article in the same issue of HeartRhythm, and there is an accompanying editorial by Dr. Krahn.³ In their research they studied much older adults, and now state that there is not any interference with pacing, but did report interference with sensing and the programmer (like ours). They also found that all interference goes away if removed a few inches. The editorial shed some doubt on the Thaker results, but we did not disprove them.

Do your findings rule out the possibility of DMP interference? Will you be doing any further research? Do you think further research in this area is needed?
I think our results should be reassuring, but there is a small possibility that we did not observe interference because it is an infrequent event and we had relatively small numbers. The next steps will be to assess longer term interactions.

Should larger DMPs (30 GB) be avoided by ICD and pacemaker patients?
No. They just shouldn’t be placed right on top of the pacemaker, and should not be used within inches of the device during programming or interrogation sessions.

Will remote monitoring be a possible future safety concern for ICD and pacemaker patients who use DMPs?
No, this will not be an issue. For patients using remote monitoring, we advise that they not put the DMP right on top of the pacemaker or use it within inches of the device during the remote interrogation sessions.