Coronary Artery Diseases
Coronary wallstents show significant late, postprocedural expansion despite implantation with adjunct high-pressure balloon inflations

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Abstract

Adjunct high-pressure balloon inflations following the delivery of oversized self-expandable Wallstents may affect their implied late, postprocedural self-expansion. Consequently, we examined 15 “Magic” Wallstents, which were implanted following a strategy of stent oversizing and subsequent adjunct high-pressure balloon inflations (16 ± 2 atm; all ≥12 atm). The excellent radiographic visibility of this stent permitted reliable quantitative coronary angiographic measurement of both lumen and stent dimensions (before and after stenting, and at follow-up). At follow-up, extent and distribution of in-stent neointimal proliferation were evaluated with volumetric intravascular ultrasound. Between postintervention and follow-up examination, mean stent diameter increased from 3.7 ± 0.4 to 4.2 ± 0.4 mm (p <0.0001); there was no significant difference in late stent expansion between proximal, mid-, and distal stent subsegments. Late stent expansion showed a significant (reverse) relation to maximum balloon size (r = −0.56, p <0.04), but not with follow-up lumen size or late lumen loss. On average, 52 ± 18% of the stent was filled with neointimal ingrowth; neointimal volume/cm stent length was 64 ± 22 mm3. Both late stent expansion (r = 0.36, p <0.02) and maximum balloon pressure (r = 0.41, p <0.001) were related to neointimal volume/cm stent but not to follow-up lumen size. Thus, despite high-pressure implantation, Wallstents showed significant late self-expansion, which resulted in larger stent dimensions at follow-up that assisted in accommodating in-stent neointimal proliferation. Conversely, late stent expansion had a significant relation to the extent of in-stent neointimal ingrowth. Beneficial and disadvantageous effects of the late stent expansion appear to be balanced, because a relation to late lumen loss or follow-up lumen dimensions was not found to be present.

Section snippets

Patient group

The study group consisted of 15 patients (12 men and 3 women, aged 61 ± 9 years) with symptomatic 1-vessel (n = 9) or 2-vessel disease (n = 6), who had Magic Wallstents (n = 15) implanted. All lesions were nonostial and located in right coronary arteries. The study was approved by the medical ethical committee of the Erasmus University Hospital, Rotterdam; all patients provided written informed consent.

Intervention procedures

All patients received 250 mg of aspirin and 10,000 U of heparin intravenously, and subsequent

Procedural details

All 15 Wallstents were successfully deployed. The stents were oversized by 1.6 ± 0.5 mm relative to the maximum lumen diameter. Adjunct balloon dilatation was performed using low-compliance balloon catheters with a maximum diameter of 4.0 ± 0.6 mm at an inflation pressure of 16 ± 2 atm. The balloon-to-artery ratio was 1.1 ± 0.1 using the postinterventional reference diameter as a reference.

Quantitative coronary angiography before and after stenting

During the intervention, overall the minimal lumen diameter increased from 1.0 ± 0.5 to 3.1 ± 0.4 mm (p

Discussion

The characteristic design of the Wallstent accounts for the self-expandable feature of this stent.1, 2, 15, 16, 17, 18 Initially, the self-expanding force of the Wallstent was thought to be sufficient for further gradual expansion after stent delivery. However, adjunct balloon dilatations were required to achieve stent dimensions that were sufficiently large to minimize the rate of subacute stent thrombosis. Recently, high-pressure balloon inflations after Wallstent delivery have been suggested,

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    Current address: Department of Cardiology, University Hospital Essen, Hufelandstrasse 55, D45122 Essen, Germany.

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