Background: Obstructive Sleep Apnea (OSA) is often undiagnosed in heart failure (HF) patients. Early identification using affordable sleep studies could improve patient outcomes in resource-limited clinical settings like Peru. The objective was to determine the frequency of OSA in hospitalized HF patients using respiratory polygraphy (RP) (Sleep Study Type III). Materials and methods: A cross-sectional study was conducted. We included patients >18 years, hospitalized with exacerbated HF, and a STOP-BANG score ≥ 3. Enrolled patients underwent overnight RP using ApneaLink Air™. Data collected included clinical parameters, the Epworth Sleepiness Scale, and echocardiography results. Statistical analysis was carried out using R Studio. Results: Of 46 enrolled patients, 39 underwent successful RP; 84.61% were diagnosed with OSA. Patients exhibited a mean Apnea-Hypopnea Index (AHI) of 14...