• Arrhythmias
• Interventional Techniques & Devices
• Cardiology Clinical Trials

Dual-chamber pacing improved long-term outcomes compared with single-chamber pacing in patients with sick sinus syndrome (SSS) in the long-term Danish Multicenter Randomized Study on AAIR Versus DDDR Pacing in Sick Sinus Syndrome (DANPACE; NCT00236158) study and should be the preferred pacing mode in these patients, according to investigators from the DANPACE study.

Bradycardia can be treated with several types of pacing, including rate-adaptive single-lead atrial pacing (AAIR), rate-adaptive ventricular (VVIR) pacing, and rate-adaptive dual-chamber pacing (DDDR). However, after VVIR pacing was shown to increase the risk of atrial fibrillation (AF) compared with physiological pacing in patients with SSS [Andersen HR, Nielsen JC, Thomsen PE et al. Lancet. 1997], AAIR and DDDR became the standard options for controlling bradycardia in SSS, said Jens Cosedis Nielsen, MD, PhD, Aarhus University Hospital, Skejby, Denmark. The Danish trial is the first large, multicenter, randomized trial that is designed to compare long-term outcomes that are associated with AAIR and DDDR pacing in patients with SSS.

In DANPACE, 1415 patients with SSS were randomly assigned to receive AAIR devices (n=707) or DDDR devices (n=708). The primary endpoint was all-cause mortality. Secondary endpoints included AF, stroke, heart failure hospitalization, and pacemaker reoperation.

After a mean follow-up of 5.4 years, the all-cause mortality rates were similar in the AAIR and DDDR groups (p=0.53). Patients in the AAIR and DDDR groups also had similar rates of stroke (p=0.56), diuretic use (p=0.89), and heart failure hospitalization (p=0.90).

Patients in the DDDR group had a lower rate of paroxysmal AF than those in the AAIR group (p=0.024) and were less likely to require pacemaker reoperation (p<0.001). As illustrated by Kaplan-Meier survival curves, these benefits, favoring dual-chamber pacing, were apparent within 12 months of randomization.

In a multivariate analysis, AAIR was associated with a 24% higher rate of paroxysmal AF (HR, 1.24; 95% CI, 1.01 to 1.52; p=0.042) and a 2-fold increase in the risk of pacemaker reoperation (HR, 2.00; 95% CI, 1.54 to 2.61; p<0.001) compared with DDDR.

A similar percentage of atrial beats were paced in the AAIR and DDDR groups (58% vs 59%; p=0.52). In the DDDR group, 65% of the ventricular beats were paced. DDDR pacing with an AV interval ≤220 milliseconds was the preferred pacing mode for patients with SSS.

DANPACE investigators concluded that AAIR pacing should no longer be used in patients with SSS, but other experts disagreed. DANPACE discussant Carina Blomström-Lundqvist, MD, Uppsala University, Uppsala, Sweden, said that AAIR pacing may have an important role in some patients with SSS, such as those with sinus dysfunction and no suspected abnormality of AV conduction. Additional studies with long-term efficacy and safety outcomes may help to determine the optimal pacing mode for different subgroups of patients with SSS.

• © 2010 MD Conference Express