Introduction. Sleep-disordered breathing (SDB) affects approximately 2–12% of the general population and the prevalence among patients with heart failure due to left ventricular dysfunction (LV–HF) is even higher. SDB is an important determinant of worse clinical outcomes in such patients. In contrast, the prevalence of SDB in pulmonary arterial hypertension (PAH) and its implications remain unclear. The purpose of this study was to compare relations between estimated apnea-hypopnoea index (eAHI) and clinical parameters in patients with LV–HF and PAH, with particular attention to the consequences of SDB.
Material and methods. Eighty-one patients were screened for SDB using commercial Holter electrographic monitoring software that allowed evaluation of eAHI. The study population consisted of 39 LV–HF patients and 42 PAH patients.

Results. While similar N-terminal pro B-type natriuretic peptide (NT-proBNP) levels were noted in both groups, LV–HF patients were characterized by higher age (63 vs. 50 years, respectively, p < 0.001), higher proportion of males (87% vs. 40%, p < 0.0001), and higher eAHI (24 vs. 14, p < 0.001) and body mass index (BMI) (28 vs. 25 kg/m2, p < 0.001) values compared to the PAH group. The prevalence of SDB, defined as eAHI > 15, was 64% in the LV–HF group and 36% in the PAH group. Parameters of time domain heart rate variability (HRV) analysis were lower in PAH vs. LV–HF. Patients with LV–HF had more ventricular arrhythmias than patients with PAH. In the LV–HF group, eAHI correlated positively with NT-proBNP level, and negatively with left ventricular ejection fraction and the mean heart rate. The median eAHI was 18.7, and patients with eAHI above the median had more supraventricular arrhythmias. In the PAH group, a negative correlation between eAHI and age was found. In the subgroup with eAHI < 15, rMSSD values were higher and idiopathic PAH predominated. The median eAHI was 8.4, and patients with eAHI above the median were younger and had higher BMI values.

Conclusions. Sleep-disordered breathing was more frequent and eAHI was higher in patients with LV–HF compared to those with PAH, although it was present in more than one third of patients in the latter group. Higher eAHI values indicated more severe hemodynamic dysfunction in patients with LV–HF. In the PAH group, higher eAHI was associated with clinical presentation at a younger age. Patients with PAH seem to have worse HRV parameters compared to patients with left ventricular dysfunction.