br Conflict of interest br Introduction Garrigue
Conflict of interest
Introduction Garrigue et al. reported that atrial overdrive pacing reduces the number of sleep Cy3-dUTP episodes in pacemaker patients without heart failure . However, this finding has not been replicated in subsequent investigations [2–5], although some meta-analysis studies [6,7], reported some effect of pacing therapy on sleep apnea. All of these studies investigated relatively short periods of pacing. Therefore, the effect of cardiac pacing on sleep-disordered breathing (SDB) is still controversial. We investigated the long-term effect of cardiac pacing on SDB in patients with conventional indications for permanent pacemakers (PPM).
Materials and methods Consecutive patients with conventional indications for pacemakers in our hospital were included. Subjects comprised 40 patients (29 men; mean age 69±9 years; mean left ventricle ejection fraction 69±8%, and body mass index 23.6±3.5kg/m2) who were diagnosed with indications for PPM (sick sinus syndrome in 23 patients, atrioventricular block in 15 patients, brady atrial fibrillation in 2 patients). All patients received polysomnographic evaluations using the Morpheus C® (Teijin, Japan) before implantation of PPM. This ambulatory cardiorespiratory polygraph records nasal airflow, chest and abdominal wall movements, oxygen saturation, heart rate, and Holter ECG. An apnea event was defined as an absence of airflow for ≥10s. Central-type sleep apnea (CSA) was defined as an apnea event with absence of chest and abdominal wall motion for more than one-third of its duration. Obstructive-type sleep apnea (OSA) was defined as an apnea event with presence of chest and abdominal wall motion for more than one-third of its duration. Mixed-type sleep apnea (MSA) was defined as an apnea event of other than the central or obstructive types. A hypopnea event was defined as a reduction in respiratory airflow of >50% for 10s associated with desaturation of >3%. After implantation of PPM, all patients received polysomnographic evaluations during use of the pacemaker settings (AAI/DDD/VVI at 70 beats per minute) using the Morpheus C® during the in-hospital-period (acute phase) and using the SAS 2100® (Teijin, Japan) during the out-patient period (chronic phase). The SAS 2100® records nasal airflow, oxygen saturation, and pulse rate. Continuous variables are expressed as means±standard deviation (SD) and categorical variables as counts or percentages. Comparisons between the 2 study groups were performed using Pearson׳s s2 test for categorical and Student t test for continuous variables, respectively. Comparisons between baseline and follow-up data were performed by paired t test. A P value <0.05 was considered significant. SPSS software, v.19.0.0, was used for all statistical analyses (SPSS Inc., IL, USA).
Discussion Young et al. reported that prevalence of SDB (defined using a cut-off of AHI≧5) was 9% in women and 24% in men in the general population . In this study, prevalence of SDB was very high in patients with conventional indications for PPM. The prevalence of SDB was 58% when the cut-off level was defined as AHI>15 and 20% when the cut-off level was defined as AHI>30, respectively. In a previous study, the majority of patients with implanted PPM suffered from unrecognized SBD . In that study, the prevalence of SDB was 59% when the cut-off level was defined as AHI>10 and 27% when the cut-off level was defined as AHI>30, respectively. Our investigation suggested long-term cardiac pacing significantly reduced the number of episodes of sleep apnea in patients with conventional PPM indications. In a previous study, a single night of overdrive pacing lowered AHI in recipients of conventional dual chamber pacemakers ; however, these findings were not replicated [2–5]. Several months of overdrive atrial pacing had no effect on obstructive or mixed sleep apnea [6,8]. Nearly all previous studies employed pacing periods of between 1 night and 3 months. In our data, the mean AHI at 1 week after implantation of PPM was not changed from baseline. This finding, which suggests that short term pacing is not effective for SDB, is compatible with most previous studies [2–5].