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Beware of interference with ICDs

I work in a cardiology practice and some of our patients have implantable cardioverter-defibrillators (ICDs). Do they need to be concerned about their smartphones interfering with their ICD?-B.C., ARIZ.

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Research has shown minimal risk of electromagnetic interference from older-generation smartphones that do not have a magnetic array (a circular array of magnets around a central charging coil). However, concerns have been raised regarding possible device-device interaction due to the presence of a strong magnetic array in the iPhone 12 recently marketed by Apple, Inc. In a study approved by the institutional review board, an iPhone 12 was brought close to a patient's ICD over the left chest area. ICD therapies were immediately suspended and this disruption persisted for the duration of the test. The researchers reproduced this result multiple times with different positions of the phone over the pocket. They concluded that this smartphone can potentially inhibit lifesaving therapy, particularly when the patient carries it in an upper chest pocket.1


Other electronic devices containing magnets may cause similar problems. The authors of this study point to a recent case report describing magnetic interference from a fitness tracker wrist band that deactivated an ICD.2


Alert patients with ICDs to these potential risks and advise them not to carry smartphones in a chest pocket.



1. Greenberg JC, Altawil MR, Singh G. Letter to the editor-lifesaving therapy inhibition by phones containing magnets. Heart Rhythm. [e-pub January 4, 2021] [Context Link]


2. Asher EB, Panda N, Tran CT, Wu M. Smart wearable device accessories may interfere with implantable cardiac devices. Heart Rhythm Case Rep. [e-pub December 12, 2020] [Context Link]



Can COVID-19 trigger new-onset diabetes?

One of my adult patients contracted COVID-19 last fall. During treatment, she was newly diagnosed with type 2 diabetes. She has no personal or family history of diabetes or prediabetes. Could this new-onset diabetes be related to her COVID-19 diagnosis?-M.S., MO.


It is possible. A growing body of evidence suggests that COVID-19 is associated with new-onset diabetes as well as severe metabolic complications from preexisting diabetes.1 For example, in a recent systematic review and meta-analysis involving more than 3,700 patients, researchers found a pooled proportion of 14.4% for newly diagnosed diabetes in hospitalized patients with COVID-19.2 In addition, they noted that newly diagnosed diabetes raises the risk of poor COVID-19 outcomes compared with no diabetes or preexisting diabetes. They concluded, "COVID-19 patients with newly diagnosed diabetes should be managed early and appropriately and closely monitored for the emergence of full-blown diabetes and other cardiometabolic disorders in the long term."


Many questions remain to be answered about the relationship between COVID-19 and diabetes; for example: How common is the phenomenon of new-onset diabetes? Is the new diagnosis classic type 1 or type 2 diabetes or a new type of diabetes? Do patients with COVID-19 remain at a higher risk for diabetes or diabetic ketoacidosis?1,2 To investigate, an international group of leading diabetes experts participating in the CoviDIAB Project have established a global registry of patients with COVID-19-related diabetes. The registry, which is fully anonymized, is open to clinicians who are members of a patient's care team and to authorized research personnel when data are transferred from other research databases.3 Healthcare professionals can contribute to the project by registering at



1. Rubino F, Amiel SA, Zimmet P, et al New-onset diabetes in COVID-19. N Engl J Med. 2020;383(8):789-790. [Context Link]


2. Sathish T, Kapoor N, Cao Y, Tapp RJ, Zimmet P. Proportion of newly diagnosed diabetes in COVID-19 patients: a systematic review and meta-analysis. Diabetes Obes Metab. 2021;23(3):870-874. [Context Link]


3. CoviDIAB Registry. Background. [Context Link]



Masking up times 2

Patients have been asking me if double-masking is a worthwhile defense against COVID-19. What should I tell them?-S.A., MASS.


You can inform patients that the CDC endorses double-masking with a cloth and medical procedure mask as one of many strategies that may help protect them from COVID-19. In one lab-based experiment, a medical procedure mask alone blocked 56% of particles from a simulated cough and a cloth mask blocked 51% of particles. But wearing the cloth mask over the medical mask blocked 85% of particles.1


Ensuring that masks fit tightly around the face is another important strategy. Knotting and tucking (knotting the ear loops of a medical mask where they attach to the mask's edges and then tucking in and flattening the extra material close to the face) improves the fit and reduces exposure to particles. In the experiment described above, a knotted and tucked medical mask used alone blocked 77% of particles.1 Use of mask fitters (small reusable devices that cinch a cloth or medical mask) is another recommended strategy that can help create a tighter fit against the face.1,2


When educating patients, make sure they know how to wear any mask correctly. It should conform to the face at the nose, under the chin, and on the cheeks so no air enters at the edges when they breathe. Also reinforce other important protective measures, such as physical distancing, avoiding crowds and poorly ventilated indoor spaces, and maintaining optimal hand hygiene.



1. Brooks JT, Beezhold DH, Noti JD, et al Maximizing fit for cloth and medical procedure masks to improve performance and reduce SARS-CoV-2 transmission and exposure, 2021. Morb Mortal Wkly Rep (MMWR). 2021;70(7):254-257. [Context Link]


2. Infectious Diseases Society of America. IDSA media briefing with CDC experts. 2021. [Context Link]