Nocturnal overdrive pacing for the treatment of sleep apnea syndrome.
STUDY OBJECTIVES: We investigated the effect of 1 week of nocturnal overdrive pacing (NOP) on the apnea-hypopnea index (AHI) in patients with a chronically implanted pacemaker and diagnosed during a screening phase with sleep apnea. DESIGN: Randomized, single-blind, crossover study. SETTING: University medical centers in Zürich, Switzerland, and Berlin, Germany. PATIENTS: Nineteen patients with mild to severe sleep apnea/hypopnea (16 men, mean age = 68.8 +/- 11.4 years) participated. The individuals did not suffer from permanent atrial arrhythmia, did not use continuous positive airway pressure, and had been implanted with atrial or dual-chamber pacemakers. INTERVENTIONS: Nocturnal lower rates were 45 and 75 beats per minute (bpm) at night for the control and NOP arms, respectively, and daytime lower rates were 60 bpm. Subjects were in each arm for 1 week. MEASUREMENTS AND RESULTS: Heart-rate increase from control (61 +/- 9 bpm) to NOP (78 +/- 4 bpm) followed by significant reduction in circulation time (24.6 seconds control, 20.7 seconds NOP; p = .04) resulted in no significant change in AHI (26.8 +/- 17.1/h control, 23.0 +/- 16.7/h NOP; p = .49). Seven subjects characterized by a higher hypopnea index, less stage 1 and 2 sleep, and less slow-wave sleep improved at least 1 AHI severity level with NOP, mainly attributable to reduction of hypopneas. CONCLUSION: NOP over a period of 1 week followed by a reduction in circulation time did not improve AHI in patients with SA. Whether an improvement by 1 AHI severity level in a specific subset of patients reflects a true response remains to be elucidated by further studies.