doi:10.1093/sleep/zsaf382engEbrahimian, SerajeddinSillanmäki, SaaraRissanen, MarikaStaykov, EricKulkas, AnttiTöyräs, JuhaBailón, RaquelGrote, LudgerBonsignore, Maria RBaumert, MathiasSomers, Virend KTerrill, PhilipLeppänen, TimoKainulainen, SamuHypoxemia and arousals modulate cardiac responses to respiratory events in obstructive sleep apneaART-2026-147872Study Objectives: Respiratory events during sleep induce immediate cardiac alterations, including increased RR intervals during events and decreased RR intervals after events. However, the extent to which related desaturations and arousals modulate these responses remains underexplored. We hypothesized that desaturations and arousals are the main contributors to respiratory event-related cardiac response, with greatest cardiac alterations expected when both are present. Methods: We analyzed RR, QT, and heart rate-corrected QT (QTc) intervals before, during, and after 4310 respiratory events from 129 obstructive sleep apnea patients. Mixed-effect statistical models were utilized to assess the influence of the presence and severity of desaturations and arousals on the cardiac electrical response to respiratory events. Results: There were no significant differences between pre- and post-respiratory event RR and QTc intervals in the absence of desaturation or arousal. Arousal (RR estimate = −23.9 ms; QTc estimate = 5.7 ms) or simultaneous desaturation and arousal (RR estimate = −32.8 ms; QTc estimate = 8.4 ms) modulated significantly (p < .05) mean RR and QTc intervals after respiratory events. Desaturation alone affected only RR intervals (estimate = −9.3 ms, p<.05). Greater desaturation depth (RR estimate = −0.09 ms; QTc estimate = 0.56 ms) and longer arousal duration (RR estimate = −3.52 ms; QTc estimate = 0.84 ms) were significant (p < .05) predictors of RR and QTc magnitude alterations after respiratory events. Conclusions: Not all respiratory events have the same effects on cardiac electrophysiology; they are associated with acute alterations after events if they cause desaturations and/or arousal, with longer arousal and deeper desaturations increasing the magnitude of cardiac responses.2026http://zaguan.unizar.es/record/16840110.1093/sleep/zsaf382http://zaguan.unizar.es/record/168401oai:zaguan.unizar.es:168401info:eu-repo/grantAgreement/ES/DGA/T39-23Rinfo:eu-repo/grantAgreement/EC/H2020/965417/EU/Revolution of sleep diagnostics and personalized health care based on digital diagnostics and therapeutics with health data integration/SLEEP REVOLUTIONThis project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No H2020 965417-SLEEP REVOLUTIONinfo:eu-repo/grantAgreement/ES/MICINN/PID2021-126734OB-C21info:eu-repo/grantAgreement/EUR/MICINN/TED2021-131106B-I00Sleep 49, 3 (2026), zsaf382 [12 pp.]byhttps://creativecommons.org/licenses/by/4.0/deed.esinfo:eu-repo/semantics/openAccess