Clinical InvestigationImproved Exercise Performance and Skeletal Muscle Strength After Simulated Altitude Exposure: A Novel Approach for Patients With Chronic Heart Failure
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Study Subjects
Patients with a history of chronic HF, left ventricular ejection fraction (LVEF) ≤35%, and peak oxygen consumption (VO2) 13–20 mL kg−1 min−1 were screened. Those with anemia (Hb <9 g/dL in women, Hb <10 g/dL in men), ferritin <100 μg/L, history of erythropoietin therapy within preceding 6 months, severe pulmonary hypertension, chronic lung disease, or a history of active angina were excluded. After informed consent was obtained, 14 subjects were enrolled. Subjects 12 and 14 did not complete the
Results
Twelve patients completed the study, and their baseline demographics are presented in Table 2. The median age was 52.5 (42–70) years, 4 subjects had ischemic cardiomyopathy, and the remaining 8 subjects had dilated cardiomyopathy. Baseline peak VO2 was 13.5 ± 1.8 mL kg−1 min−1, and baseline LVEF was 31.7 ± 7.6%. Both male and female subjects were mildly anemic with median hemoglobin values of 12.6 (11.4–14.6) and 12.2 (12.1–14.0) g/dL, respectively (normal ranges in our laboratory: men
Discussion
In this pilot study of ambulatory HF patients, we show that outpatient altitude exposure to 2,700 m was feasible, safe, and well tolerated. New therapies for patients with HF will be measured against their ability to improve exercise performance, which is a primary aim in this population. The only large trial of exercise training in HF could not show significant benefit in the primary outcomes of all-cause mortality, cardiovascular mortality, and hospitalizations.16 We hypothesized that
Acknowledgments
The authors thank Hypoxico for providing the simulated altitude enclosure and air delivery unit used in this study.
Disclosures
Dr Maybaum is listed as an inventor in a patent application by Montefiore Medical Center entitled “Hypoxic Conditioning in Patients with Exercise Limiting Conditions.” All of the other authors report no potential conflict of interest.
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See page 391 for disclosure information.
Dr. Saeed and Dr. Bhatia contributed equally to this work.