Hoole SP, et al. - This paper explored the effects of patent foramen ovale (PFO) on obstructive sleep apnoea syndrome (OSAS). Collected data demonstrated that the prevalence of PFO in OSAS seemed to be no higher than in the general population. Although PFO closure was safe and effective, it did not improve respiratory polygraphy measures of OSAS severity. The improvement in Epworth Sleepiness Score (ESS) and Sleep Apnoea Quality of Life Index (SAQLI) likely reflect residual benefits from continuous positive pressure ventilation (CPAP).