Reduction of inappropriate implantable cardioverter-defibrillator therapies using enhanced supraventricular tachycardia discriminators: the ReduceIT study

Purpose: Inappropriate implantable cardioverter-defibrillator (ICD) shocks are associated with greater healthcare resource utilization, poorer quality-of-life, and higher mortality. We aimed to investigate the performance of enhanced supraventricular tachycardia (SVT) discrimination algorithms (morphology discrimination, rate stability, and sudden or chamber onset) for reducing inappropriate ICD therapies in patients with ICD/cardiac resynchronization therapy devices.

Methods: This prospective, non-randomized, multicenter study (ReduceIT) study took place at 56 sites across Germany and Estonia. Adults at risk of sudden cardiac death undergoing St. Jude Medical™ ICD or CRT-D implantation were included. The primary endpoint was freedom from inappropriate ICD shock at 12 months and was analyzed in the intention to treat (ITT) and per-protocol population.

Results: Overall, 733 patients (65.9 ± 11.4 years) were included, of which 40.9% and 59.1% received a single- and dual-chamber detection device, respectively. During follow-up (median 11.9 [0-21.6] months), 96.3% of patients experienced no inappropriate therapy (ITT). The sensitivity, specificity, and accuracy for VT/VF were 91.9%, 95.5%, and 94.7%, respectively. In the per-protocol population (n = 620), the proportion of patients free from inappropriate shock at 12 months was 98.4% (n = 610; 95% CI 97.1-99.2%) and exceeded the expected value of 93% (p < 0.0001) which was derived from the rates in the SPICE, ATPonFastVT, and DECREASE studies. A total of 44 patients (6.0%) died during follow-up, 19 deaths were cardiac-related which is consistent with a meta-analysis of EMPIRIC, MADIT-RIT, ADVANCE III, and PROVIDE. Serious device and procedure-related adverse effects occurred in 9.8% of patients.

Conclusions: In ICD/CRT-D devices with advanced SVT discriminators, device programming according to clinical setting and detection chamber significantly reduces the rate of inappropriate ICD shocks without compromising patient safety. The algorithms and settings described herein have particular clinical importance and their employment may be of benefit to ICD recipients.