5 March 2008
MedWire News: Late incomplete stent apposition (ISA), also termed stent malapposition, is more common after sirolimus-eluting stent (SES) than bare-metal stent (BMS) implantation but does not appear to increase the risk for clinical events even in the long term, research shows.
Pathology study findings suggest ISA after coronary stenting may contribute to late-stent thrombosis, but until now studies of whether late ISA is related to negative long-term clinical consequences have been limited to 12-month follow-up periods.
R Hoffman (University Hospital Aachen, Germany) and colleagues analyzed pooled data from three multicenter, randomized trials comparing SES with BMS with 4 years of follow-up available.
The researchers looked at intravascular ultrasound (IVUS) images at angiographic follow-up performed at 6 months or 8 months after coronary stenting, available for 325 patients, to determine the presence of ISA defined as one or more stent struts lacking contact with the underlying arterial wall (unapposed).
Patients treated with SES had ISA more frequently than patients treated with BMS (25% vs 8.3%, p<0.001).
Canadian Cardiology Society Class III or IV angina at stent implantation (odds ratio [OR]=4.69) and absence of diabetes (OR=3.42) predicted ISA.
Over 4 years of follow-up, there was a trend toward more myocardial infarctions (MIs) among BMS and SES patients with ISA than without, but the authors point out that only five of all 21 MIs across both groups were related to the target vessel.
Kaplan-Meier analysis showed that survival free from major adverse cardiac events (MACE) was similar in SES-treated patients with and without ISA, at 11.1% and 16.3% at 4 years, respectively.
The authors conclude that "ISA detected by IVUS, considering the currently used sensitive IVUS definition for ISA, appears to have no significant negative impact on the total number of clinical events or on ST during a 4-year follow-up period."
In an accompanying editorial, however, Antonio Colombo and Azeem Latib from San Raffaele Scientific Institute and EMO Centro Cuore Columbus, respectively, in Milan, Italy, highlighted that there was only one case of stent thrombosis identified in the cohort.
This makes it "impossible to draw any conclusions about a possible association between what appears to be a frequent finding of ISA and a rare event such as stent thrombosis," they wrote.
Nevertheless, they said that other factors such as delayed healing, inflammation, and excessive vascular remodeling and hypersensitivity probably contribute to the development of stent thrombosis in patients with late ISA.
Colombo and Latib concluded: "Importantly, what remains unanswered is what we do about late ISA when we find it?
"Considering the current study, the majority of late ISA may be no more than an incidental finding. The lack of knowledge should not lead us to pursue an 'innocent bystander'."
Heart 2008; 94: 322-328
作者:admin@医学,生命科学 2011-02-19 05:18