Clinical Study attributes
Of the more than 2 million Americans with heart failure (HF), up to 70% have disturbed sleep that worsens the dyspnea, fatigue, and reduced daytime function associated with HF. Exercise improves sleep in healthy people but the effects of exercise have not been tested in patients with HF. A controlled, randomized trial is proposed to compare the effects of 16 weeks of usual activity (control) with 16 weeks of regular, supervised walking exercise (treatment), on cardiac function and sleep. Approximately 170 subjects with NYHA Class I, II, or III stable heart failure will be recruited. Subjects in the treatment group will walk for exercise up to 5 times a week for up to 30 minutes. The purpose of this randomized trial is to examine the effects of 16 weeks of regular walking exercise on cardiac function, sleep, and quality of life in persons with stable New York Heart Association (NYHA) Class I, II or III heart failure. The specific aims are: 1. To compare the physiologic measures of cardiac function (peak oxygen utilization, exercise capacity, nocturnal arterial oxygen desaturations, and heart rate variability) and self-reported quality of life (i.e., symptoms of dyspnea and fatigue, and the ability to perform activities of daily living) of patients randomized to walking vs. control condition. 2. To compare the somnographic (sleep fragmentation, slow wave sleep, sleep efficiency) and self-reported (sleep effectiveness, sleep disturbance, and nap supplementation) measures of sleep for HF patients randomized to walking vs. control condition. 3. Considering the extent of apnea-hypopnea episodes at study entry and group assignment (walking vs. control), explore whether HF patients with frequent apnea-hypopnea episodes (more than 20 per hour) in the walking group experience greater pretest-posttest improvements in physiologic cardiac and somnographic function, when compared with HF patients with few apnea-hypopnea episodes (less than 20 per hour) assigned to walking, or the control group of HF patients with frequent or few apnea-hypopnea episodes. HYPOTHESES: 1. Heart failure patients who walk regularly will have better cardiac function than the control group. Heart failure patients who walk regularly will have higher self-reported quality of life, less shortness of breath/fatigue, and greater ability to perform activities of daily living than the control group. 2. Heart failure patients who walk regularly will have better sleep than the control group. 3. Heart failure patients with frequent episodes of slowed or stopped breathing during sleep who walk regularly will have a greater improvement in pretest-posttest measures of cardiac function than heart failure patients with few episodes of slowed or stopped breathing during sleep who walk regularly, or the control groups with frequent or few breathing difficulties during sleep. Heart failure patients with frequent apnea-hypopnea episodes who walk regularly will have a greater improvement (i.e., larger difference) in pretest-posttest somnographic sleep measures of efficient, fragmented, and slow wave sleep, than heart failure patients with few apnea-hypopnea episodes who walk regularly, or the control groups with frequent or few apnea-hypopnea episodes.
