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Dual-chamber settings in ICDs reduced risk for inappropriate shock
Compared with single-chamber settings, dual-chamber settings for implantable cardioverter defibrillators were associated with reduced risk for inappropriate shock without increases in morbidity and mortality, according to the results of the OPTION study.
According to the study background, use of dual-chamber ICDs may allow better discrimination of supraventricular arrhythmias and therefore reduce inappropriate shocks, but also may be linked to detrimental ventricular pacing.
Christof Kolb, MD, PhD, and colleagues enrolled 462 patients with de novo primary or secondary prevention indications for ICD placement and left ventricular ejection fraction ≤40% despite an optimal pharmacotherapy regimen in the single blind OPTION trial.
Patients received atrial leads and dual-chamber defibrillators (Ovatio DR model 6550, Sorin Group) that were randomly assigned to programming with single- or dual-chamber settings.
In the dual-chamber arm, a discrimination algorithm (PARAD+) that differentiates supraventricular arrhythmias from ventricular arrhythmias and a mode that minimizes ventricular pacing (SafeR) were activated. In the single-chamber arm, acceleration, stability and long cycle search discrimination criteria were activated and pacing was set to VVI mode at 40 bpm.
The primary outcomes were time to first occurrence of inappropriate ICD shock and occurrence of all-cause death or CV hospitalization, defined as hospitalization for congestive HF, symptomatic atrial fibrillation, cardioversion of AF, stroke and undetected/untreated ventricular tachycardia. Follow-up was 27 months.
During the study period, time to first inappropriate shock was longer in the dual-chamber group than the single-chamber group (HR=2.5; 95% CI, 1.2-5.3). Inappropriate shocks were received by 4.3% of those in the dual-chamber group vs. 10.3% in the single-chamber group (P=.015).
Rates of all-cause death or CV hospitalization were 20% for the dual-chamber group vs. 22.4% for the single-chamber group, satisfying the predefined margin for equivalence (P for equivalence <.001), according to the researchers.
There were no significant differences between the groups in system-related complications.
“The results of our trial add an important piece of evidence for the reduction of inappropriate shocks with dual-chamber ICDs,” Kolb, from Deutsches Herzzentrum München, Klinik für Herz- und Kreislauferkrankungen, Faculty of Medicine, Technische Universität München, Munich, and colleagues wrote. “Dual-chamber therapy combined with the SafeR algorithm provides a net benefit by reducing inappropriate shocks without increasing [CV] morbidity and mortality.”
Disclosure: The study was supported by Sorin CRM. The researchers report financial ties with Biotronik, Boston Scientific, Medtronic, Sorin and St. Jude Medical.