Abstract
INTRODUCTIONStent implantation is traditionally performed of the lesion predilatation using a balloon. The aims of the present study were the following: 1) to know the viability, efficacy and safety of the stent implantation without predilatation; 2) to determine the clinic and angiographic restenosis rate, 3) to identify the predictive variables of restenosis, and 4) to analyse the intimal hyperplasia pattern using this technique.
PATIENTS AND METHODS
Three different protocols were performed:
Protocol A: From 500 consecutive angioplasties performed in a 13 months period, 107 patients were selected because of their susceptibility for direct stent implantation. The immediate results were analyzed and the groups with and without predilatation were compared.
Protocol B: One hundred patients with successful direct stent implantation were studied for 12 months. The clinic and angiographic restenosis rate were determined and the predictive variables of angiographic reestenosis were evaluated. Angiographic restenosis was defined as continuous variable - late loss or minimum luminal diameter (MLD) during at the follow-up - and as binary variable - stenosis >50% in the treated segment-
Protocol C: Forty-five patients with successfully direct stent implantation and 23 patients with similar characteristics in whom predilatation was made, were included. An intravascular echography was performed in all them. For the intimal hiperplasia analysis, five transversal cuts were established through the stent with the following transversal measurements:l area of the vessel, stent and lumen. In addition, the excluded plaque by the stent and the intimal hyperplasia expressed as percentage were calculated.
RESULTS
Protocol A: The implantation was successful in 93.5% of the patients. Failure to implant a direct stent was observed in 7 patients. This was related with the calcium presence and advanced age The fluoroscopy duration and contrast quantity were lower in the direct stent group than the predilatation group.
Protocol B: The clinic restenosis rate was 4%. There were no deaths off cardiac origin. Angiographic follow-up was made in 82% of the patients. The binary reestenosis rate was 11%.
Diabetes mellitus was observed in 55.6% of the patients with an angiographic restenosis compared with 12.3% of the patients without reestenosis (p<0.05). Multivariate analysis identified the diabetes mellitus as a predictive variable of binary reestenosis with an odds ratio of 7.1 The minimum luminal diameter immediately post- stent was identified as a predictive variable of late loss and the reference diameter as a predictive variable of the minimum luminal diameter at the follow-up.t.
Protocol C: the inflation pressure was higher in the direct stent group compared with predilatation's group (13 ±3 atm versus 10±2 atm, p<0.05). Moreover, the stent areas were bigger in the group with no predilatation compared with the standard implantation. The intimal proliferation was similar in the five cuts analysed through the stent in both groups. The excluded plaque by the stent was correlated with the intimal proliferation in the with (r=0.37; p=0.005) and without (r=0.33; p=0.005) predilatation.
CONCLUSIONS
The implantation of the direct stent is a safe and efficient procedure in selected patients with a low clinic and angiographic restenosis rate. The most important predictive factor of the angiographic reestenosis is the presence of diabetes mellitus. The intimal hyperplasia pattern following direct stenting is diffuse and homogeneous through the stent, being similar to the pattern observed with the standard implanation technique. Intimal hyperplasia correlates with the excluded plaque by the stent.
| Date of Award | 5 Feb 2003 |
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| Original language | Spanish |
| Supervisor | Vicens Martí Claramunt (Director) & Ignasi Carrió Gasset (Tutor) |