Relationship between obstructive sleep apnea severity index and left ventricular function and volume.
OBJECTIVE
Obstructive sleep apnea (OSA) causes increased cardiovascular morbidity and mortality, including systemic arterial hypertension, coronary heart disease, heart rhythm and conduction disorders, heart failure and stroke. In our study, we aimed to assess left ventricular mass and myocardial performance index (MPI) in OSA patients.


METHODS
A cross-sectional study conducted between May 2007 and August 2009 in a tertiary hospital in Istanbul, Turkey.


METHODS
Forty subjects without any cardiac or pulmonary disease referred for evaluation of OSA had overnight polysomnography and echocardiography. According to the apnea-hypopnea index (AHI), subjects were classified into three groups; mild OSA (AHI: 5-14/h; n=7), moderate OSA (AHI: 15-29/h; n=13), and severe OSA (AHI: ;ge;30/h; n=20). The thickness of the interventricular septum (IVS) and left ventricular posterior wall (LVPW) were measured by M-mode along with left ventricular mass (LVM) and LVM index (LVMI). The left ventricular MPI was calculated as (isovolumic contraction time + isovolumic relaxation time)/aortic ejection time by Doppler echocardiography.


RESULTS
No differences were observed in age or body mass index among the groups, but blood pressures were  higher in severe OSA compared with moderate and mild OSA. In severe OSA, the thickness of the IVS (11.6 [1.7 mm]), LVPW (10.7 [1.7 mm]), LVM (260.9 [50.5 g]), and LVMI (121.9 [21.1g/m2]) were higher than in moderate OSA (9.4 [1.3 mm]; 9.9 [1.6]; 196.4 [35.2]; 94.7 [13.2 g/m2], respectively) and mild OSA (9.8 [2.4 mm], 8.9 [2.0 mm], 187.6 [66.2 g], 95.8 [28.6 g/m2], respectively). In severe OSA, MPI (0.8 [0.2]) was significantly higher than in mild OSA (0.5 [P<.01]) but not significantly higher than moderate OSA (0.8 [0.1]).


CONCLUSIONS
OSA patients have demonstrable cardiac abnormalities that worsen with the severity of apnea. The MPI may have utility in subsequent OSA studies, possibly as a surrogate outcome measure.
School of Medicine, Department of Pulmonary and Sleep Medicine, Mayis University, Samsun, Turkey. nejataltintas@gmail.com
Nejat
N
Altintas
Ekrem
E
Aslan
Aysen
A
Helvaci
Atul
A
Malhotra
D000328:Adult; D003430:Cross-Sectional Studies; D015150:Echocardiography, Doppler; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction; D017286:Polysomnography; D012720:Severity of Illness Index; D020181:Sleep Apnea, Obstructive / Q000150:complications / Q000503:physiopathology*; D014421:Turkey; D018487:Ventricular Dysfunction, Left / Q000209:etiology* / Q000503:physiopathology; D016277:Ventricular Function, Left