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Reduced Risk for Inappropriate Implantable Cardioverter-Defibrillator Shocks With Dual-Chamber Therapy Compared With Single-Chamber Therapy: Results of the Randomized OPTION Study (Optimal Anti-Tachycardia Therapy in Implantable Cardioverter-Defibrillator Patients Without Pacing Indications)
Study Questions:
Does dual-chamber implantable cardioverter-defibrillator (ICD) implantation in patients without pacing indication result in fewer inappropriate shocks than single-chamber ICD?
Methods:
The OPTION (Optimal Anti-Tachycardia Therapy in Implantable Cardioverter-Defibrillator Patients Without Pacing Indications) prospective multicenter trial enrolled 462 patients with primary or secondary prevention indications for ICD placement and with left ventricular ejection fraction ≤40%. All patients received dual-chamber defibrillators (Sorin Group, Milan, Italy), and were randomized to be programmed either with dual-chamber or single-chamber settings. Ventricular tachycardia detection was required at rates between 170 and 200 pm, and ventricular fibrillation detection was activated above 200 bpm.
Results:
During a follow-up period of 27 months, the time to the first inappropriate shock was significantly longer in the dual-chamber setting arm (p = 0.012, log-rank test), and 4.3% of patients in the dual-chamber setting group compared with 10.3% in the single-chamber setting group experienced inappropriate shocks (p = 0.015). Rates of all-cause death or cardiovascular hospitalization were 20% for the dual-chamber setting group and 22.4% for the single-chamber setting group, and satisfied the predefined margin for equivalence (p < 0.001).
Conclusions:
The authors concluded that therapy with dual-chamber settings for ICD discrimination combined with algorithms for minimizing ventricular pacing was associated with reduced risk for inappropriate shock compared with single-chamber settings, without increases in mortality and morbidity.
Perspective:
Usage rates for dual- versus single-chamber ICDs vary greatly across hospitals and implanting physicians. Many studies show no difference in inappropriate shocks, while others suggest that dual-chamber ICDs are “smarter” to differentiate supraventricular from ventricular arrhythmias. Differences in results may be due to different patient populations, proprietary algorithms, and varying time to detection. The latter has a huge impact on inappropriate therapy rates, as shown in the MADIT-RIT trial. Presumably time to detection in the present study was set the same in both groups, although that is not explicitly stated. On the balance, there does not seem to be evidence to suggest dual-chamber implantation with the hope of reducing inappropriate therapy in most patients without pacing indications.
Keywords: Tachycardia, Ventricular, Follow-Up Studies, Ventricular Fibrillation, Stroke Volume, Hospitalization, Defibrillators, Implantable, Arrhythmias, Cardiac
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