Obstructive Sleep Apnea and Sleep-Disordered Breathing in Heart Failure
A 42 year-old male with minimal previous medical history is hospitalized with newly diagnosed decompensated heart failure. He is short of breath at rest [New York Heart Association (NYHA) class IV heart failure]. His exam demonstrates evidence of congestion and volume overload, and he appears to be well-perfused with normal cardiac output. His primary symptoms include fatigue and dyspnea. In addition, he endorses chest discomfort at night. His BMI is 32 and his left ventricular ejection fraction (LVEF) on transthoracic echocardiogram (TTE) is 22%. Electrocardiogram (ECG) and cardiac telemetry demonstrate frequent premature ventricular contractions and several runs of non-sustained ventricular tachycardia. Left- and right-heart catheterization reveals no obstructive coronary artery disease, elevated left- and right-sided filling pressures consistent with congestion/volume overload, normal pulmonary pressures, and normal cardiac output and cardiac index. He has never been evaluated for sleep-disordered breathing and he denies excessive daytime sleepiness. He is treated with intravenous diuretics, and appropriate goal-directed medical therapy for non-ischemic cardiomyopathy is initiated. The patient receives heart failure education regarding nutrition and lifestyle modifications.
During his seven-day hospitalization, he is screened for sleep-disordered breathing on the second night of his stay. A bedside sleep study reveals an apnea hypopnea index of 21 (signifying 21 episodes of apnea, hypopnea, or respiratory-effort related arousals per hour of sleep) consistent with a diagnosis of obstructive sleep-disordered breathing. Treatment with continuous positive airway pressure (CPAP) is initiated on the third night of his stay.
At the time of hospital discharge, the patient is given prescriptions for his standard heart failure medications which were begun during the hospitalization as well as a prescription for home CPAP therapy. Outpatient validation polysomnography (PSG) confirms a diagnosis of obstructive sleep apnea. Over the next six months, the patient follows up regularly with his heart failure and sleep medicine clinics. He is not re-hospitalized for heart failure, and he reports excellent compliance with his medications and nocturnal CPAP use. His BMI does not change.
At six months, his symptoms are improved to New York Heart Association (NYHA) class II heart failure (mild limitation of activity). ECG and 24-hour Holter monitor reveal no evidence of ventricular dysrhythmias. TTE at six months shows and LVEF of 41%, an improvement from 22% at the time of initial presentation.
Figure 1, from overnight polysomnography, shows four 30-second epochs of sleep from an adult sleep study. Shown are two complete obstructive apneas with associated events as below.
- #1: obstructive apneas
- #2: paradoxical movement of the thorax and abdomen in the effort channels
- #3: oxyhemoglobin desaturation
- #4: arousal
- #5: leg movement
Abbreviations: LOC: left oculogram; ROC: right oculogram; CHIN: chin EMG; C3A2, C4A1: central EEG leads; O1A2, O2A1: occipital EEG leads; LLEG: left leg EMG; RLEG: right leg EMG; PSNR: snoring channel; CPAP: CPAP flow channel; FLOW: nasal pressure flow channel; THOR: thorax effort channel; ABDM: abdominal effort channel; EKG: electrocardiogram; SAO2: oxygen saturation channel.
Which of the following is FALSE in regards to the association between obstructive sleep apnea and heart failure?