Clinical Significance of the Presence of Oscillatory Breathing Both at Rest and During Exercise in Cardiac Patients.

Cardiac patients often experience nocturnal and daytime oscillatory breathing (OB). OB noted at rest sometimes becomes unclear or even disappears during exercise. We evaluated the physiological significance of OB by comparing the clinical characteristics of cardiac patients who manifested OB only at rest (group A), only during exercise (group B), and both at rest and during exercise (group C).Among 3,432 cardiac patients who underwent cardiopulmonary exercise testing (CPX), 114, 94, and 65 patients were identified as group A, B, and C, respectively. Left ventricular ejection function was 57 ± 17% in group A, 49 ± 20% in group B, and 41 ± 21% in group C (P < 0.05 for all comparisons among the 3 groups). The level of brain natriuretic peptide (BNP) was significantly higher in group C than in groups A and B. The peak VO2 was lower and the VE-VCO2 slope was higher in groups B and C than in group A.The present findings suggest that cardiac function is more impaired in cardiac patients who manifest OB both at rest and during exercise than in cardiac patients who manifest OB only at rest or only during exercise.