Dual-chamber setting in ICDs leads to fewer inappropriate shocks

When comparing risk of inappropriate implantable cardioverter-defibrillator (ICD) shocks in two types of therapy, researchers in the OPTION study found a significant advantage in dual-chamber therapy. Fewer inappropriate shocks were delivered to patients on dual-chamber than on single-chamber settings, especially those programmed with algorithms for minimizing ventricular pacing.

OPTION, the Optimal Anti-Tachycardia Therapy in Implantable Cardioverter-Defibrillator Patients Without Pacing Indications study, compared long-term outcomes for 462 patients with left ventricular ejection fraction of less than or equal to 40 percent with implanted ICDs. Lead author Christof Kolb, MD, PhD, of the Technische Universität München in Munich, and colleagues  followed these patients for 27 months.

All patients received OVATIO DR model 6550 (Sorin Group) dual-chamber devices implanted between June 2006 and April 2009. Of that group, 230 were in the dual-chamber setting arm and 223 in the single-chamber setting arm. To those assigned the dual-chamber setting arm, an algorithm was activated.

There was no increase in adverse events in the use of dual- vs. single-chamber implantations. Patients with single-chamber settings were 2.5 times as likely to receive inappropriate shocks. Fewer dual-chamber setting patients received at least one shock than those in the single-chamber group (16.1 percent vs. 22.9 percent).

Inappropriate shocks occurred at a rate of 7.3 percent total over the 27-month period with no time-point clustering; 2.6 percent of patients in the dual-chamber group and 7.6 percent of patients in the single-chamber group received at least one inappropriate shock over 12 months. At the end of 27 months, 4.3 percent of dual-chamber patients and 10.3 percent of single-chamber patients received at least one inappropriate shock. Supraventricular tachycardia and lead failure were responsible for most events (73.6 percent and 25.5 percent, respectively).

Appropriate shock rates were similar in both groups.

All-cause death or cardiovascular hospitalizations happened at a rate of 20 percent of dual-chamber setting patients and 22.4 percent of single-chamber setting patients over 27 months. Kolb et al wrote that ventricular pacing did not differ significantly between the two groups, nor did system-related complication rates.

They did note, however, there was a high crossover rate from dual-chamber to single-chamber therapy that may have diluted some findings between the two groups.

Kolb et al wrote that dual-chamber therapy with a pacing algorithm appears optimal for treatment as the number of inappropriate shocks was reduced with no increase in complications, mortality or morbidity.

This study appeared online Oct. 1 in the Journal of the American College of Cardiology: Heart Failure.