Impact of obstructive sleep apnoea on left ventricular mass and global function

Abstract

Obstructive sleep apnoea syndrome (OSAS) might be a cause of heart failure. The present study aimed to assess left ventricular mass and myocardial performance index (MPI) in OSAS patients. A total of 67 subjects without any cardiac or pulmonary disease, referred for evaluation of OSAS, had overnight polysomnography and echocardiography. According to apnoea-hypopnoea index (AHI), subjects were classified into three groups: mild OSAS (AHI: 5-14; n = 16), moderate OSAS (AHI: 15-29; n = 18), and severe OSAS (AHI: > or = 30; n = 33). Thickness of interventricular septum (IVS) and posterior wall (LVPW) were measured by M-mode, along with left ventricular mass (LVM) and LVM index (LVMI). Left ventricular MPI was calculated as (isovolumic contraction time+isovolumic relaxation time)/aortic ejection time by Döppler echocardiography. There were no differences in age or body mass index among the groups, but blood pressures were higher in severe OSAS compared with moderate and mild OSAS. In severe OSAS, thickness of IVS (11.2+/-1.1 mm), LVPW (11.4+/-0.9 mm), LVM (298.8+/-83.1 g) and LVMI (144.7+/-39.8 g x m(-2)) were higher than in moderate OSAS (10.9+/-1.3 mm; 10.8+/-0.9 mm; 287.3+/-74.6 g; 126.5+/-41.2 g x m(-2), respectively) and mild OSAS (9.9+/-0.9 mm; 9.8+/-0.8 mm; 225.6+/-84.3 g; 100.5+/-42.3 g x m(-2), respectively). In severe OSAS, MPI (0.64+/-0.14) was significantly higher than in mild OSAS (0.50+/-0.09), but not significantly higher than moderate OSAS (0.60+/-0.10). In conclusion, severe and moderate obstructive sleep apnoea syndrome patients had higher left ventricular mass and left ventricular mass index, and also left ventricular global dysfunction.