Temporal changes in device-derived daily activity related to ventricular arrhythmias from the CERTITUDE registry

There have been limited data examining the temporal relationship between device-derived daily activity and ventricular arrhythmias (VAs).

We aimed to assess whether activity predicted VAs or VAs predicted changes in activity.

The CERTITUDE registry includes over 55,000 implanted devices active on Home Monitoring. Daily data on activity are captured by a 1-axis accelerometer. Temporal changes in activity during treated VAs were analyzed using the first event and 7-day activity windows (baseline, pre-event, and postevent). Baseline period was defined as 31 to 38 days prior to VA. VAs were categorized by heart rate (≤200 beats/min, >200 beats/min) and treatment (shock or antitachycardia pacing). Differences were assessed using the binomial proportion test and case-crossover analysis.

A total of 5631 devices (3688 implantable cardioverter-defibrillators, 1943 cardiac resynchronization therapy defibrillators) were analyzed with a cumulative follow-up duration of 18,354 years (5.6 million days). Patients with VA events >200 beats/min with shock (n = 593) had a significant decline in activity post-VA with a median -8.7% reduction (interquartile range -24.6% to 7.3%, P < 0.001). However, there was no reduction in activity before VA events >200 beats/min (P = .690) or before or after VA events >200 beats/min with antitachycardia pacing. However, VA events ≤200 beats/min with shock had reductions in activity following the event (-5.8%, interquartile range -29.5% to 12.3%, P = .003). Case-crossover analyses confirmed lower activity rates following for VA events >200 beats/min with shock.

In the CERTITUDE registry, we have shown a temporal decline in device-derived activity following VA events >200 beats/min and for VA events <200 beats/min treated with a shock, but we did not find changes in activity preceding a shock event.