Impact of small thrombus formation in restenotic bare-metal stent lesions associated with acute coronary syndrome: identification by optical coherence tomography.
BACKGROUND
Although in-stent restenosis (ISR) after bare-metal stent (BMS) implantation is considered to be clinically benign, ISR is often associated with adverse complications, such as acute coronary syndrome (ACS). The frequency, type, and location of thrombi in ISR lesions and their clinical presentation have not yet been precisely validated.


METHODS
Thirty angiographic ISR lesions occurring within 3 to 8 months after stenting were evaluated by optical coherence tomography (OCT). A thrombus was defined as a mass protruding into the lumen with an irregular surface, and its type was divided into red or white. The maximum size of a thrombus and the longitudinal distance from the thrombus to the narrowest lumen were measured.


RESULTS
A thrombus was identified in 2 patients by angiography and in 10 patients by OCT (7% vs. 33%; P=0.01). OCT showed that 9 patients had white thrombus and another patient had both types of thrombi. ACS relevant to ISR was seen in 6 patients, and the frequency of ACS was significantly higher in patients with thrombus than in those without thrombus [50% (5/10) vs. 5% (1/20); P=0.003]. The maximum size of the thrombus was 412 ± 220 µm in height, 424 ± 251 µm in width, and the longitudinal distance between the thrombus and the minimum lumen area was 0.3 ± 0.7 mm.


CONCLUSIONS
One third of ISR lesions following BMS deployment dominantly contained a white thrombus, and half of them were associated with ACS. A small thrombus formation adjacent to the narrowest lumen in an ISR lesion may therefore contribute to the clinical presentation of ACS.
Yamamoto
Masanori
M
Cardiovascular Center, Chiba-Hokusoh Hospital, Nippon Medical School, Chiba, Japan.
Takano
Masamichi
M
Cardiovascular Center, Chiba-Hokusoh Hospital, Nippon Medical School, Chiba, Japan. Electronic address: takanom@nms.ac.jp.
Murakami
Daisuke
D
Cardiovascular Center, Chiba-Hokusoh Hospital, Nippon Medical School, Chiba, Japan.
Inami
Toru
T
Cardiovascular Center, Chiba-Hokusoh Hospital, Nippon Medical School, Chiba, Japan.
Kobayashi
Nobuaki
N
Cardiovascular Center, Chiba-Hokusoh Hospital, Nippon Medical School, Chiba, Japan.
Shirakabe
Akihiro
A
Cardiovascular Center, Chiba-Hokusoh Hospital, Nippon Medical School, Chiba, Japan.
Inami
Shigenobu
S
Division of Cardiology, Nippon Medical School, Tokyo, Japan.
Okamatsu
Kentaro
K
Cardiovascular Center, Chiba-Hokusoh Hospital, Nippon Medical School, Chiba, Japan.
Ohba
Takayoshi
T
Cardiovascular Center, Chiba-Hokusoh Hospital, Nippon Medical School, Chiba, Japan.
Aoki
Satoshi
S
Cardiovascular Center, Chiba-Hokusoh Hospital, Nippon Medical School, Chiba, Japan.
Seino
Yoshihiko
Y
Cardiovascular Center, Chiba-Hokusoh Hospital, Nippon Medical School, Chiba, Japan.
Mizuno
Kyoichi
K
Division of Cardiology, Nippon Medical School, Tokyo, Japan.
D054058:Acute Coronary Syndrome / Q000000981:diagnostic imaging / Q000209:etiology*; D000368:Aged; D000369:Aged, 80 and over; D023903:Coronary Restenosis / Q000000981:diagnostic imaging / Q000209:etiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008670:Metals / Q000009:adverse effects*; D008875:Middle Aged; D015607:Stents / Q000009:adverse effects*; D013927:Thrombosis / Q000000981:diagnostic imaging / Q000209:etiology*; D041623:Tomography, Optical Coherence / Q000379:methods; D014463:Ultrasonography
D008670:Metals