CHF is associated with a high rate of re-hospitalization and significant morbidity and mortality and is considered as a major medical and economic problem. To date, few studies have investigated the prevalence, severity, persistence and the role of SAS during cardiac decompensation. For different pathophysiological considerations, it is assumed that SAS is exacerbated during AHF. Therefore SAS is not conventionally screened during this phase. This assumption has been questioned recently by some studies which showed stability of the type of SAS and its severity between the decompensation episode and the stable HF.