825 Central Sleep Apnea and Sinus Bradycardia

Abstract

Abstract Introduction Central sleep apnea (CSA) is characterized by a lack of respiratory drive during sleep resulting in repetitive periods of apneas. There are multiple manifestations of CSA as defined by the ICSD3. CSA with Cheyne-Stokes Breathing (CSB) is characterized by a series of crescendo-decrescendo pattern of ventilation followed by central apnea and is often associated with heart failure. Bradyarrythmias have been associated with obstructive sleep apnea (OSA), but an association with central sleep apnea is less clear. Report of case(s) A 76 y/o male with no significant past medical history but with multiple instances of sinus bradycardia on previous EKGs, was referred to sleep medicine for evaluation of snoring, witnessed apneas, and daytime sleepiness. He had no history of CVA, CHF, atrial fibrillation, renal disease, or opioid use. PSG was completed for suspected OSA, and revealed moderate CSA (AHI 10.9 using hypopnea type 1B criteria, CAI 6.1). Central apneas at the latter portion of the study were consistent with a CSA-CSB. Awake heart rate at time of study was 44 bpm. During sleep, his heart rate ranged from 39–89 with a mean of 57 bpm. Due to this unexpected central apnea finding, cardiac evaluation was recommended and echocardiogram revealed a LVEF of 51%, a dilated left atrium, normal left ventricle chamber size, no wall motion abnormalities, and an inability to assess left sided filling pressures. EKG was consistent with sinus bradycardia without AV blocks. Holter monitor revealed sinus rhythm with moderate burden of ectopy. He underwent CPAP titration which revealed an effective CPAP pressure to control obstructive events, but central apneas persisted without CSB pattern. Conclusion In this patient, CSA/CSA-CSB was found in the absence of known risk factors for CSA. Although potentially an early sign of HFpEF related to his longstanding sinus bradycardia, this case raises the question as to whether sinus bradycardia in isolation could decrease cardiac output enough to destabilize ventilation and promote this finding of CSA/CSA-CSB. Support (if any):