INTRODUCTION

Stents are devices commonly used in the treatment of coronary artery obstruction.1-4 We have carried out phase I to III experiments with the Atlas stent with good results.5 This coil stent has design advances such as a flat platinum wire construction (90% platinum and 10% iridium) and two parallel rows of gold point welds (less than 1% of the surface in contact with the arterial wall is gold, the rest is platinum). The metal coverage of the artery is 14.3% (Figure 1).

Fig. 1. Detail of the Atlas stent showing its sinusoidal configuration, flat wire, and gold weld points.

Various studies have been made with different platinum stents (angiostent).6,7 Platinum is a biocompatible metal that, in principle, shows less tendency to platelet adhesion and thrombosis.

Tubular stents of stainless steel have less immediate elastic loss than coil type stents of nitinol and stainless steel,8,9 a factor that contributes to the greater rate of restenosis with coil stents.

Changes in stent configuration are being tested,10 particularly the material used in stent coatings (pyrolytic carbon, phosphorylcholine, silicon carbide11).

METHODS

We clinically evaluated a platinum coil stent of improved design in our hospital that is more economical (Atlas stent).

It was implanted dismounted (diameters of 2.5, 3.0, 3.5 and 4.0 mm and lengths of 10, 18 and 25 mm) in 169 non-consecutive patients who had an indication for stent implantation.

The aim of the study was to assess the immediate clinical and angiographic result, presence of complications, clinical evolution, and appearance of major cardiac events (MACE) (death, myocardial infarction with or without Q wave, and need for urgent revascularization) during the hospital stay. Another aim of the study was to assess the long-term clinical and angiographic outcome.

We used conventional stent insertion techniques. All patients were premedicated with clopidogrel or ticlopidine and aspirin at optimal doses. During the procedure, intravenous unfractionated heparin was administered in therapeutic doses.

Studies were recorded on 35-mm cinema film and the angiographic measurements were made with calipers. We measured the reference arterial diameter, percentage of initial obstruction, residual diameter after angioplasty, diameter achieved with the stent, and the quality of coronary flow using the TIMI classification.

Angiographic controls were made according to the study protocol (more than 4 months), clinical indications, or the results of ischemia induction tests.

RESULTS

From February 1999 to December 2000, a total of 887 stents were implanted in our service. In 169 patients, 226 Atlas stents were implanted (19%) for the treatment of 194 lesions in 183 coronary arteries. An average of 1.3 stent was implanted per patient. The mean age was 6010.8 years and 135 patients were men. The clinical history, indications, number of treated vessels, artery treated, type of lesion, and stent diameters and lengths are shown in Table 1. The angiographic characteristics of the lesions before and after the procedure are summarized in Table 2.

Only 9.5% of the stents were implanted directly. In 95.6% of the cases treated with stents the final coronary flow was TIMI 3.

Immediate success was obtained in 98.8% of cases (Figures 2 and 3); 2 patients had acute intra-stent thrombosis.

Fig. 2. Anterior descending coronary artery with a proximal type B1 lesion of 90%.

Fig. 3. Result after implantation of the Atlas stent with respect to the diagonal branch and the radiopacity of the stent.

In 6 cases the Atlas™ stent became deformed, but this did not affect the angiographic result or procedure. Catheterization was repeated in 2 patients without producing restenosis.

Control coronary arteriography was performed on 40.9% of all patients in 8.44.1 months. In 76.4%, arteriography was performed in compliance with the protocol, in 11.7% for symptoms, and in 11.7% due to the results of ischemia induction tests. In the analysis of this subgroup, angiographic restenosis was documented in 27.9% of cases. In 2.15%, angiographic evaluation was not possible.

The clinical follow-up of 126 patients (85.79%) was carried out at an average of 14.136.89 months (Table 3).

DISCUSSION

Stents reduce the incidence of restenosis12,13 and improve results in ostial lesions,14 total chronic lesions,15 saphenous bridges,16 and, as a provisional measure17 compared with conventional angioplasty.

In order to reduce costs, De Scheerder et al18 tried a stent made by them with good results.

Our initial experience was with a stainless steel coil type stent, in phase I-IV of investigation.19,20 The stent was improved by changes in design and material. Platinum is more ductile, non-corrosive, and has less elastic recoil and thrombogenicity.21 In addition, it does not produce allergic reactions.22 Its radiopacity facilitates implant assessment, but interferes with the angiographic evaluation of intimal proliferation. Platinum is non-corrosive.23 In addition, platinum is not ferromagnetic, so it does not interfere with magnetic resonance imaging.

With the Atlas stent we achieved an angiographic and clinical success rate that was similar to reports in the literature.12,13

Our work has methodological limitations that preclude reaching definitive conclusions with regard to the percentage of restenoses. Nevertheless, the results were encouraging and at our hospital this stent is an effective alternative that was useful for reducing the cost of stent implantation.

ACKNOWLEDGMENTS

We would like to thank Mr. German Quintana, Dr. Alonso Autrey, Dr. José Navarro, and the engineer Daniel Capuano.

The authors participated in the development of stent, but claim that they do not have any potential economic conflict of interest in relation to the device evaluated.

Correspondence: Dr. A. Abundes

Carracci n.° 15, Colonia San Juan Mixcoac. 03730 México DF. México.