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N-terminal pro-B-type natriuretic peptide and functional capacity in patients with obstructive sleep apnea

Maeder, Micha ; Ammann, Peter ; Rickli, Hans ; Schoch, Otto ; Korte, Wolfgang ; Hürny, Christoph ; Myers, Jonathan ; Münzer, Thomas

In: Sleep and Breathing, 2008, vol. 12, no. 1, p. 7-16

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    Title
    • N-terminal pro-B-type natriuretic peptide and functional capacity in patients with obstructive sleep apnea
    Author
    • Maeder, Micha. Division of Cardiology, Kantonsspital, St. Gallen, Switzerland
    • Ammann, Peter. Division of Cardiology, Kantonsspital, St. Gallen, Switzerland
    • Rickli, Hans. Division of Cardiology, Kantonsspital, St. Gallen, Switzerland
    • Schoch, Otto. Multidisciplinary Sleep Center and Division of Pulmonary Medicine, Kantonsspital, St. Gallen, Switzerland
    • Korte, Wolfgang. Institute for Clinical Chemistry and Hematology, Kantonsspital, St. Gallen, Switzerland
    • Hürny, Christoph. Center of Geriatric Medicine and Rehabilitation, Bürgerspital, St. Gallen, Switzerland
    • Myers, Jonathan. Cardiology Division, Palo Alto Veterans Affairs Medical Center, Stanford University, Palo Alto, CA, USA
    • Münzer, Thomas. Center of Geriatric Medicine and Rehabilitation, Bürgerspital, St. Gallen, Switzerland
    Document Type
    • Postprint
    OAI-PMH Identifier
    • oai:doc.rero.ch:320813
    Summary
    The obstructive sleep apnea syndrome (OSAS) is associated with cardiovascular abnormalities including left ventricular hypertrophy, left ventricular diastolic dysfunction, and endothelial dysfunction. The present study evaluated whether N-terminal pro-B-type natriuretic peptide (NT-proBNP) and peak oxygen consumption (peak VO2), both integral markers of cardiovascular function, are related to OSAS severity. In addition, we tested whether NT-proBNP levels depend on body composition in OSAS patients, similar to what has been reported in patients without OSAS. Eighty-nine patients with untreated OSAS underwent NT-proBNP measurement, dual X-ray absorptiometry, and cardiopulmonary exercise testing. In a representative subgroup (n = 32), transthoracic echocardiography was performed. The severity of OSAS was classified based on apnea-hypopnea index (AHI) values as mild (AHI 5-15h−1), moderate (AHI 15-30h−1), and severe (AHI >30h−1). OSAS was mild in 19 (21%), moderate in 21 (24%), and severe in 49 (55%) patients. NT-proBNP levels did not differ among patients with mild [30 (10-57)], moderate [37 (14-55)], and severe [24 (13-49) pg/ml; p = 0.8] OSAS and were not related to body mass index (r = 0.07; p = 0.5), percent lean body mass (r = −0.17; p = 0.1), and percent fat mass (r = 0.18; p = 0.1). Percent predicted peak VO2 was on average normal and did not differ among patients with mild (115 ± 26), moderate (112 ± 23), and severe OSAS (106 ± 29%; p = 0.4). Body weight-indexed peak VO2 did not differ among patients with mild (31.9 ± 10.3), moderate (32.1 ± 7.9), and severe OSAS (30.0 ± 9.9ml kg−1 min−1; p = 0.6) either. Lower NT-proBNP (β = −0.2; p = 0.02) was independently but weakly associated with higher body weight-indexed peak VO2. In the echocardiography subgroup, NT-proBNP was not significantly related to left ventricular mass index (r = 0.26; p = 0.2). In conclusion, NT-proBNP and peak VO2 are not related to OSAS severity, and NT-proBNP poorly reflects left ventricular hypertrophy in OSAS. The lack of a relationship between NT-proBNP and OSAS severity is not due to a significant influence of body composition on NT-proBNP. There is an association between higher NT-proBNP and lower peak VO2, indicating that NT-proBNP is a marker of cardiorespiratory fitness in patients with OSAS. However, the association is too weak to be clinically useful