The arrival of a new generation of smartphones is reigniting an important debate: Do these devices, which contain powerful magnets, pose an increased risk for people with pacemakers or implantable cardiac defibrillators, or ICDs?

For years, patients have been told to keep their cell phones more than six inches from their ICD or pacemaker. The concern is that the electromagnetic fields emitted by the phone could be misinterpreted by the device and alter its functions, even shut it down. Patients are told to use the ear opposite the pacemaker site and not to put their phone in a pocket next to the implanted device.

These recommendations, however, are based on studies performed years ago. Since then, technology has changed and there has been less evidence of adverse reactions. A 2017 study concluded these recommendations may now be obsolete but, notably, said this situation should be continually monitored because of the rapid evolution of technology.

The newest smartphones have stronger magnets, raising new concerns. A cardiologist and professor at St. Louis University School of Medicine recently explored the issue in MedPage Today, noting that most people use their phone without giving any thought to how close it is to their chest. This may not be a big concern with the earlier smartphones, but people with pacemakers or ICDs, or who might be a candidate for one in the future, should avoid buying one of the newer phones until more research is done.

Taking it a step further, they recommend that patients have their cell phone tested for any interference with their cardiac device soon after it is implanted. Smart advice for people who frequently use their smartphone.