Abstract 14449: Worsening Sleep Disordered Breathing is Associated with Lower Peak Oxygen Consumption in Patients with Hypertrophic Cardiomyopathy
Background: Peak oxygen consumption per unit time (pkVO2) is the best and most reproducible measure of cardiopulmonary fitness. It predicts survival in patients with left ventricular systolic dysfunction and may also be predictive in patients with hypertrophic cardiomyopathy (HCM). Sleep disordered breathing (SDB) is a treatable and highly prevalent disorder in patients with HCM that may be associated with worsening of symptoms yet the impact of SDB on pkVO2 in HCM is not known.
Methods: We prospectively performed overnight oximetry and cardiopulmonary exercise testing on echocardiographically confirmed HCM patients seen at the Mayo Clinic, Rochester. Clinically significant SDB was considered present if oxygen desaturation index (ODI, number of ≥4% desaturations per hour) was ≥10. We investigated the relationship between cardiopulmonary exercise testing and the presence and severity of SDB.
Results: Of the 200 patients studied (age 53±16 years; 123 male; LVOT pressure gradient at rest 42±36 mmHg), 63 (32%) patients were diagnosed with SDB (ODI≥10). Presence of SDB was associated with lower pkVO2 (16 vs 21 mlO2/kg/min; p<0.0001), which translated to lower metabolic equivalents (4.7 vs 6.1 METs; p<0.0001). The figure below demonstrates significant negative correlation between pkVO2 and severity of SDB. After adjustment for confounders, SDB remained significantly associated with lower pkVO2 (p<0.0001) and lower metabolic equivalents (p=0.0002).
Conclusions: The presence and severity of SDB may negatively influence cardiopulmonary fitness in patients with HCM. SDB may therefore be an important and potentially modifiable cause of impaired exercise tolerance and even mortality in this population.
- © 2010 by American Heart Association, Inc.