Nocturnal Hypoventilation May Have a Protective Effect on Ischemic Heart Disease in Patients with Obesity Hypoventilation Syndrome

The importance of nocturnal hypoventilation (nHyp) in the development of cardiovascular comorbidity (CVM) in patients with obesity hypoventilation syndrome (OHS) is controversial. We recently hypothesized that nHyp may have a protective effect on CVM in OHS. The aim of this study was to evaluate the link between nHyp and CVM in patients with OHS. We performed a retrospective analysis of the clinical records of 60 patients with OHS. The initial population was divided into two groups: (1) 31 subjects with OHS and nHyp (nhOHS); (2) 29 individuals with OHS without nHyp (wnhOHS). All patients had also obstructive sleep apnea. Anthropometric data, medical history, electrocardiogram, pulmonary function testing, arterial blood gas test, and sleep recordings were collected. Patients with nhOHS, compared with those wnhOHS, showed higher values of PaCO 2 (48.75 ± 3.78 vs. 46.91 ± 2.09 mmHg; p = 0.023), lower percentage of ischemic heart disease (3.2% vs. 20.7%; p = 0.042), higher oxygen desaturation index (ODI; 55.10/h ± 28.76 vs. 38.51/h ± 23.21; p = 0.017), and higher total sleep time (TST90) with SpO 2 <90% (53.58% ± 26.90 vs. 25.64% ± 21.67; p = 0.000). Moreover, individuals in the nhOHS group showed a significantly different (p = 0.031) distribution of the three ODI tertiles 0-32/h, 33-72/h, >72/h compared with those in wnhOHS group (19.4% vs. 37%, 41.9% vs. 51.7%, 38.7% vs. 10.3%, respectively). Subsequent discriminant analysis correctly classified nhOHS and wnhOHS in 66.7% of the cases. Ours is the first study analyzing the correlation between nHyp and CVM in patients with OHS. We showed that nHyp in OHS may have a protective effect on cardiovascular morbidity, in particular on ischemic cardiac disease.