P2856Risk factors for the first and second inappropriate implantable cardioverter-defibrillator therapy: a subanalysis of the NIPPON storm study

Abstract

Abstract Background Implantable cardioverter-defibrillator (ICD) including cardiac resynchronization therapy with defibrillator (CRT-D) has become an established therapeutic option to reduce the risk of sudden cardiac death. However, there are risks for the first and second inappropriate ICD shock events, which have not been well clarified. Objective To clarify the risk factors for the first and second inappropriate ICD therapy events. Methods We conducted a post-hoc, secondary analysis of the data from a multicenter, prospective, observational study (the Nippon Storm Study), designed to clarify the risk factors for electrical storm. The analysis included the data of 1549 of the 1570 patients with ICD or CRT-D enrolled into the study. An inappropriate event was defined as any inappropriate ICD or CRT-D therapy delivered, including antitachycardia pacing (ATP) or ICD shock for sinus tachycardia, atrial fibrillation (AF)/ atrial flutter (AFL), regular supraventricular tachycardia, or for non-arrhythmic events Results Over a median follow-up of 28 months, 293 inappropriate ICD therapy events occurred in 153 of the 1549 patients (10.0%) in the study sample, with 106 inappropriate ICD shock events identified in 72 (4.6%) patients. Inappropriate therapy events were unlikely during sleep. On multivariate Cox regression analysis, the risk factors for the first inappropriate ICD therapy included, younger age (hazard ratio (HR), 0.986; 95% confidence interval (CI), 0.973–0.998; p=0.028), AF/AFL (AF/AFL; HR, 2.324; 95% CI, 1.372–3.939; p=0.002), ICD implantation (HR, 2.377; 95% CI, 1.332–4.244; p=0.004), and multiple versus single stimulation zone (HR, 1.852; 95% CI, 1.163–2.951, p=0.010). After the first inappropriate ICD therapy event, any interventions were performed, including a change in the ICD programming (n=122), initiation or change in medication (n=33) and catheter ablation (n=7), or a combination of interventions. The rate of the second inappropriate ICD therapy event after treatment of the first was 37.6% at one year. The patients who underwent an intervention after the first inappropriate ICD event showed a lower risk of the second event, compared to those without any intervention (1.0% versus 6.0% at one week, 4.2% versus 22.3% at one month, 27.3% versus 57.4% at one year, log-rank p<0.001). On multivariate Cox regression analysis, the risk factors for the second inappropriate ICD therapy was no-intervention after the first inappropriate ICD therapy (HR, 3.521; 95% CI, 1.773–6.993; p=0.001). Conclusions The risk for the first inappropriate ICD therapy increased for younger patients, use of ICD versus CRT-D and a prior history of AF/AFL. Intervention after the first inappropriate ICD therapy could reduce the risk of the second inappropriate event.