Sleep Rate Mode of Pacemaker-Dependent Patients with Sick Sinus Syndrome Increases Dipper Blood Pressure and Dipper Heart Rate Patterns

Abstract

Cardiovascular event rates of patients with a dipper blood pressure (BP) and dipper heart rate (HR) pattern are lower than those of patients with nondipper BP and HR patterns. However, how the pacemaker mode affects the diurnal BP and HR patterns remains unclear. We enrolled nine patients (average age 74.4 ± 6.6 years, 4 males and 5 females) with sick sinus syndrome who required atrial pacing. We investigated sequential 6-month pacing regimens (DDD mode at 60 bpm and sleep rate mode). We set the lower rate of sleep rate mode as follows: 60 bpm during the daytime and 50 bpm during the nighttime. The order of pacing mode was randomized, with crossover design. Ambulatory BP monitoring was performed at baseline, 6 months, and 12 months, BP category was classified into four groups (extreme dipper, dipper, nondipper, and riser pattern), and HR was classified into dipper and nondipper patterns. Nighttime HR during the sleep rate mode was significantly lower than that at DDD (57.1 ± 6.2 versus 63.5 ± 3.8 bpm, P = 0.001). The dipper HR pattern was increased in the sleep rate mode compared with those at baseline or DDD mode (versus baseline: 89% versus 44%, P = 0.035; versus DDD: 89% versus 22%, P = 0.004). The dipper BP pattern significantly increased in the sleep rate mode compared with the baseline (56% versus 11%, P = 0.035), but the difference between the sleep rate mode and DDD mode was statistically marginal (56% versus 22%, P = 0.081). The pacemaker settings in the sleep rate mode increased the dipper HR and BP patterns in pacemakerdependent patients with sick sinus syndrome.