Patient Activity

Patient activity in CIEDs is measured through an integrated circuit accelerometer embedded in the pulse generator, which in applicable patients can also be used for rate‐responsive pacing. The accelerometer detects both the frequency and amplitude of patient motion and translates this into a proportional electrical signal updated each minute. The specific algorithm for translating these signals into an adjudicated minute of “activity” is proprietary and may vary by manufacturer. For example, in Boston Scientific devices, force of motion of at least 25 milligravities—corresponding to an approximate walking speed of 2 mph—denotes an “active” minute.6 Device platforms for storing activity information vary, but they generally track minutes per day of activity according to calendar days. Some specific models that are common in clinical practice (such as the Medtronic Adapta and Sensia pacemaker systems) do not store activity in an analyzable format, so these and similar devices were excluded from our analysis.

All activity information was directly downloaded from the applicable programmer in device clinic at the time of clinical device interrogations. For all manufacturers, the raw data files are encrypted and require translation into an analyzable format using proprietary software specific to each company. These data were then used to calculate activity in hours per day for each patient in the 30 days prior to their in‐office interviews. For analyses reported here we restricted attention to participants with at least 7 days' evaluable data.