Call for caution with portable electronic devices

Stronger magnets used in newer portable electronic devices such as the Apple AirPods Pro charging case, the Apple Pencil 2nd Generation and the Microsoft Surface Pen may interfere with the function of implanted cardioverter defibrillators (ICDs).

A Swiss study has shown 3D mapping of the magnetic field of such devices could effectively disable ex vivo defibrillators within about 2cm.

“These devices can cause a problem when carried in your shirt or jacket pocket in front of the chest, as well as when you are lying on the couch and resting the electronic device on your chest, or if you fall asleep with the electronic device,” the lead author said in an AHA statement.

“The main thing to remember is that any electronic device may be a danger, especially ones with a magnet inside.”

The research team has yet to confirm the interactions with implanted devices in volunteer patients. However the AHA has long recommended that magnets be kept away from pacemakers and ICDs.

Read more in Circulation: Arrhythmia and Electrophysiology.

Cardiac warning for donepezil

The TGA has issued an updated safety advisory for the dementia drug donepezil after receiving adverse event reports of cardiac conduction disorders.

In a statement released on 28 February it said Product Information (PI) documents for donepezil are being updated to advise caution in patients with known QTc prolongation or a family history of this condition. The updates also advise caution when donepezil is used in combination with other medicines known to prolong the QTc interval, including:

• class IA antiarrhythmics such as disopyramide
• class III antiarrhythmics such as amiodarone, sotalol
• certain antidepressants such as citalopram, escitalopram, amitriptyline
• other antipsychotics such as phenothiazine derivatives, pimozide, ziprasidone
• certain antibiotics such as clarithromycin, erythromycin, moxifloxacin.

“The cardiac conduction disorders caused by donepezil can be potentially life threatening, so monitoring of cardiac function may be required in at-risk individuals or where this adverse event is suspected,” the TGA statement said.

There have been 18 cases of atrioventricular block, atrioventricular block complete, atrioventricular block second degree, bundle branch block, bifascicular block or Torsades de Pointes associated with donepezil reported to the TGA up to 5 January 2022, it added.

Low switching rates for oral anticoagulants in AF patients

A primary care study has found low rates of switching between oral anticoagulants in patients with atrial fibrillation.

Data from 15,020 general practice patients who were recorded as having been commenced on warfarin or a DOAC for AF between 2013 and 2017 showed that 5.7% of patients switched their oral anticoagulant within 12 months.

Patients were most likely to switch from warfarin (9.4%) and dabigatran (8.9%) and less likely to switch from apixaban (2.6%) and rivaroxaban (4.0%).

Kidney disease appeared to be a significant factor in switching oral anticoagulants, as patients with an estimated glomerular filtration rate (eGFR) <30 mL/min were more likely to switch from DOACs to warfarin and less likely to switch from warfarin, compared to those with an eGFR >60 mL/min.

The findings are published in Expert Review of Clinical Pharmacology.