A new study shows that many implantable cardioverter defibrillators (ICDs), which are designed to detect and correct dangerous heart rhythms, are programmed to too low a setting, delivering painful shocks for heart rhythms that aren’t dangerous. Making a simple change in the way physicians set or program the device can lead to a dramatic 80 to 90 percent reduction in inappropriate therapies delivered for rhythms not life threatening.

Cardiology researchers at the University of Rochester Medical Center, Rochester, NY, found that simply raising the heart rate at which the device is set to fire significantly increased survival, lowering the risk of death by 55 percent compared to patients whose devices used traditional programming. This is above and beyond the usual decrease in mortality associated with defibrillator therapy, leading to an overall 70 percent reduction in death.

Currently, around 200,000 ICDs are implanted in the US every year. Most are set to initiate therapy when the heart rate exceeds around 170 beats per minute, but rates of 180 or 190 may be related to increased activity or exercise. Setting the device to fire at a higher rate of 200 beats per minute reduced the risk of experiencing a first inappropriate therapy by 79 percent compared to standard programming. Fewer shocks also corresponded with less energy delivered to the heart, which study authors believe contributed to the reduced risk of death.