Algorithm-based reduction of inappropriate defibrillator shock: Results of the Inappropriate Shock Reduction wIth PARAD+ Rhythm DiScrimination–Implantable Cardioverter Defibrillator Study

Abstract

BACKGROUND Inappropriate shocks (IS) continue to have a major negative impact on patients implanted with defibrillators.OBJECTIVE The purpose of this study was to assess IS reduction with the PARAD1 discrimination algorithm in a general population implanted for primary or secondary prevention. METHODS ISIS-ICD (Inappropriate Shock Reduction wIth PARAD1Rhythm DiScrimination-Implantable Cardioverter Defibrillator) was a 2-year international, interventional study in patients implanted with a dual implantable cardioverter-defibrillator (ICD) or triple-chamber defibrillator (cardiac resynchronization therapy-defibrillator [CRT-D]) featuring PARAD1. IS (shocks not delivered for ventricular tachycardia or fibrillation) were independently adjudicated. The primary endpoint was percentage of IS-free patients at 24 months. Primary and worst-case analyses of annual incidence rates of patients with 1 IS, overall and per defibrillator type, were conducted. RESULTSIn total, 1013 patients (80.7% male; age 67.1 6 11.4 years; 68%/30%/2% primary/secondary/other indication) were enrolled and followed for a median of 552 days (interquartile range 354; 725). Of 993 analyzed patients programmed with PARAD1, 14 had 1 IS, corresponding to a percentage free from IS of 98.1% (95% confidence interval [CI] 96.8%-98.9%). Annual incidence rates (per 100 personyears) of patients with IS were 1.0 (95% CI 0.59-1.69) and 2.1 (95% CI 1.46-3.02) in the primary and worst-case analyses, respectively. In ICD patients, rates were 1.2 (95% CI 0.68-2.23) and 2.3 (95% CI 1.47-3.53), and in CRT-D patients 0.59 (95% CI 0.19-1.83) and 1.8 (95% CI 0.93-3.44) per 100 person-years.CONCLUSION The annual rate of defibrillator patients with IS using the enhanced PARAD1 discrimination algorithm alone ranged from 1.0 to 2.1 per 100 person-years in a general population implanted for primary or secondary prevention.

Low rates of inappropriate shocks in contemporary real-world implantable cardioverter defibrillator patients: the CARAT observational study

“…Appropriate ICD therapy was delivered in 13.4% of the study cohort, whereas appropriate shocks were mandated in 5.0% of patients at 2 years. Consistently with previous studies, 5 a lower rate of appropriate shocks is found in the CRT-D arm. The rate of appropriate ICD shocks in CARAT was lower than in recently published trials such as the EU-CERT trial (7.1% within 2.7 years) 9 and the PRAETORIAN trial (19.5% in the subcutaneous ICD subgroup and 13.5% in the transvenous ICD subgroup, median follow-up 49.1 months) 6 , 7 and comparable to the DANISH trial (11.5% within 5.5 years), 13 potentially associated with a reduced proportion of ischaemic heart failure aetiology in the present study (51%).…”

“…As the PARAD+® algorithm had been used as default tachyarrhythmia detection algorithm in the presence of a functional atrial lead, CARAT confirms results of previous studies such as OPTION 3 , 4 or ISIS-ICD 5 in terms of arrhythmia discrimination in dual-chamber devices. The present study also reports low inappropriate shocks in single-chamber devices, where arrhythmia discrimination is based on a combination of stability, acceleration, and ‘long cycle gap’ to identify atrial fibrillation.…”

Pseudo-Electrical Storm in Patients with Implanted Cardioverter Defibrillator

“…Inappropriate shocks are one of the main issues to be avoided as they cause patient discomfort, are potentially proarrhythmic, and reduce battery life. The two main causes of inappropriate shock are failure in discriminating supraventricular arrhythmias (SVA) [2][3][4][5][6][7][8][9][10][11][12][13]. Frequently SVA is associated with a fast-ventricular response leading ventricular rate to fall into VT/VF detection zone causing inappropriate therapy release.…”

Pseudo-Electrical Storm in Patients with Implanted Cardioverter Defibrillator

“…Signal misinterpretation is the other big deal leading to inappropriate shocks. It may depend on some programmed variables; easily editable, external, and farfield interferences; or lead failure that usually requires an interventional approach [2][3][4][5][6][7][8][9][10][11][12][13].…”