Relationship between sleep-disordered breathing level and acute onset time of congestive heart failure.

Sleep-disordered breathing (SDB) is frequently observed in patients with congestive heart failure. Recent studies have shown that SDB negatively affects the onset of congestive heart failure; however, no studies have addressed the relationship between the level of SDB and the onset time of acute dyspnea. We hypothesized that SDB affects the acute onset time of dyspnea (AOT) and investigated the relationship between SDB and AOT. We examined 80 patients (mean age, 61.6 years) with congestive heart failure in a clinically stable condition. AOT was divided into 5 time periods (0:00 - 6:00, 6:00 - 12:00, 12:00 - 18:00, 18:00 - 24:00, and unknown). The apnea-hypopnea index (AHI) was obtained based on the results of polysomnography (PSG) to evaluate the severity of SDB. Acute dyspnea occurred in 59 (73.7%) of the 80 patients. When we divided the patients into an AHI < 5 group and an AHI >or= 5 group, there was no significant difference in the AOT; however, a significant difference was observed in those divided into AHI < 20 and AHI >or= 20 groups (P < 0.001). The patients with AHI >or= 20 had more acute dys-pnea between 18:00 - 24:00 and between 0:00 - 6:00 than those with AHI < 20 (32% and 19%, and 4.1% and 4.1%, respectively). Severe SDB patients tended to have acute dyspnea between midnight and dawn. The results suggest SDB might be one of the risk factors of heart failure.