Impaired coronary flow reserve in obstructive sleep apnea and its improvement after continuous positive airway pressure therapy: a transthoracic Doppler echocardiographic study.
BACKGROUND
It is reported that patients with obstructive sleep apnea syndrome (OSAS) show endothelial dysfunction and that treatment of OSAS by continuous positive airway pressure (CPAP) therapy improves it.


OBJECTIVE
In this study we evaluated coronary flow reserve (CFR), which is considered to be affected by coronary microvascular dysfunction, and the change in CFR during treatment of OSAS by CPAP.


METHODS
Eleven patients who were diagnosed as having OSAS by polysomnography (PSG) were studied. Phasic coronary flow velocity was obtained in the left anterior descending coronary artery at baseline and during hyperemic conditions with transthoracic 2D echocardiography. CFR was defined as the ratio of hyperemic to basal mean diastolic velocity. CFR was obtained before and after the initiation of CPAP therapy.


RESULTS
Coronary flow reserve was decreased (<2.5) in 8 of 11 (73%) patients at baseline. After CPAP therapy, CFR of these 8 patients increased significantly.


CONCLUSIONS
Coronary flow reserve was decreased in 73% of the patients with OSAS and was significantly improved after CPAP therapy.
Department of Cardiology, Kawasaki Medical School, 577 Matsushima, Kurashiki, 701-0192, Japan. obasekkk@med.kawasaki-m.ac.jp.
Kikuko
K
Obase
Department of Cardiology, Kawasaki Medical School, 577 Matsushima, Kurashiki, 701-0192, Japan.
Hiroyuki
H
Okura
Division of Respiratory Diseases, Kawasaki Medical School, 577 Matsushima, Kurashiki, 701-0192, Japan.
Keiji
K
Mouri
Department of Cardiology, Kawasaki Medical School, 577 Matsushima, Kurashiki, 701-0192, Japan.
Tomoko
T
Maehama
Department of Cardiology, Kawasaki Medical School, 577 Matsushima, Kurashiki, 701-0192, Japan.
Akihiro
A
Hayashida
Department of Cardiology, Kawasaki Medical School, 577 Matsushima, Kurashiki, 701-0192, Japan.
Nozomi
N
Watanabe
Department of Cardiology, Kawasaki Medical School, 577 Matsushima, Kurashiki, 701-0192, Japan.
Yoji
Y
Neishi
Department of Cardiology, Kawasaki Medical School, 577 Matsushima, Kurashiki, 701-0192, Japan.
Takahiro
T
Kawamoto
Division of Respiratory Diseases, Kawasaki Medical School, 577 Matsushima, Kurashiki, 701-0192, Japan.
Mikio
M
Oka
Department of Cardiology, Kawasaki Medical School, 577 Matsushima, Kurashiki, 701-0192, Japan.
Kiyoshi
K
Yoshida
Continuous positive airway pressure therapy; Coronary flow reserve; Coronary microvascular dysfunction; Obstructive sleep apnea syndrome