Depressed myocardial contractile reserve in patients with obstructive sleep apnea assessed by tissue Doppler imaging with dobutamine stress echocardiography.
BACKGROUND
Hypoxia has been suggested to affect myocardial contractile function in patients with obstructive sleep apnea (OSA). We sought to determine whether myocardial contractile reserve (MCR), as evaluated by echocardiographic tissue Doppler imaging with dobutamine stress (TDDS), might be depressed in OSA patients.


METHODS
Thirty patients with suspected OSA (25 men and 5 women; mean age, 51 +/- 11 years [+/- SD]) underwent overnight polysomnography and TDDS. Peak myocardial systolic velocity (Sm) and peak myocardial early diastolic velocity (Em) in the 12 myocardial segments of the left ventricular (LV) walls were averaged, and the mean Sm and Em during TDDS were compared between patients with apnea-hypopnea index (AHI) <15/h (group 1, n = 13) and those with AHI >/= 15/h (group 2, n = 17). MCR was calculated as the difference between the resting and peak Sm during TDDS.


RESULTS
In both groups, Sm increased dose dependently during TDDS. However, the relative increase in Sm was significantly lower in group 2, resulting in a lower value of MCR (5.5 +/- 1.2 cm/s vs 7.4 +/- 1.3 cm/s, p < 0.001). The Em was lower in group 2 compared with group 1 throughout TDDS. MCR was correlated significantly with AHI (r = - 0.67, p < 0.0001), resting Em (r = 0.53, p < 0.005), and body mass index (r = - 0.46, p < 0.05) independent of the LV mass index.


CONCLUSIONS
OSA can affect MCR, implying an etiologic contribution from repetitive hypoxic events. TDDS could identify subtle abnormalities of OSA-related cardiac involvement.
Okuda
Nobuaki
N
Third Department of Internal Medicine, Osaka Medical College, 2-7, Daigaku-cho, Takatsuki City, Osaka, 569-8686, Japan.
Ito
Takahide
T
Emura
Narutsugu
N
Suwa
Michihiro
M
Hayashi
Tetsuya
T
Yoneda
Hiroshi
H
Kitaura
Yasushi
Y
D000328:Adult; D015150:Echocardiography, Doppler / Q000379:methods*; D025401:Echocardiography, Stress / Q000379:methods*; D005260:Female; D006352:Heart Ventricles / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction / Q000502:physiology*; D015588:Observer Variation; D017286:Polysomnography; D012146:Rest / Q000502:physiology; D012720:Severity of Illness Index; D020181:Sleep Apnea, Obstructive / Q000150:complications / Q000000981:diagnostic imaging / Q000503:physiopathology*; D018487:Ventricular Dysfunction, Left / Q000150:complications / Q000000981:diagnostic imaging / Q000503:physiopathology*