Cardiovascular effects of obstructive sleep apnoea and effects of continuous positive airway pressure therapy: evidence from different study models.

Background: Cardiovascular consequences of obstructive sleep apnoea (OSA) and the effects of continuous positive airway pressure (CPAP) therapy on blood pressure, endothelial dysfunction and major adverse cardiovascular events (MACE) have been studied over decades using different study designs. However, clinical findings from different study models on cardiovascular outcomes are sometimes contradictory. Methods: A literature search was conducted in PubMed for randomised controlled trials, meta-analyses, population-based epidemiological studies and OSA cohort studies up to September 2023 investigating the cardiovascular effects of OSA and CPAP in adults with OSA on the following cardiovascular end-points: blood pressure, arterial hypertension, endothelial function and MACE (myocardial infarction, stroke, transient ischaemic attack or cardiovascular death). The level of evidence for these outcomes was discussed on the basis of different study models. Results and conclusions: There is high-level evidence of a causal relationship between OSA and arterial hypertension and endothelial dysfunction, as well as on higher MACE incidence among subgroups of patients with untreated OSA. The cardiovascular effects of OSA depend on the severity of OSA, symptoms, phenotype and comorbidities. The blood pressure-lowering effect of CPAP is mainly observed in uncontrolled and treatment-resistant hypertension. The MACE risk reduction in OSA depends on good long-term CPAP adherence. Younger, sleepy patients with more severe OSA, higher hypoxaemic burden and without overt cardiovascular end-organ disease may particularly benefit from CPAP treatment in terms of cardiovascular risk reduction. Randomised controlled trials of CPAP or other effective OSA treatments in primary cardiovascular prevention and in patients at highest risk are lacking.