It is unclear whether stent implantation or balloon angioplasty is superior for treating symptomatic coronary artery stenosis in smaller vessels. In addition, there is no conclusive data illustrating the role of heparin-coated stents in these smaller vessel lesions.

The objective of the Heparin-Coated Stents in Small Coronary Arteries Trial (COAST) was to assess angiographic and clinical benefit of a heparin-coated stent (Jostent Flex) in the stenoses of small native coronary arteries.

A total of 21 centers throughout Europe participated in the trial. Investigators randomized 605 patients with angina to one of three arms: balloon angioplasty, uncoated Jostent Flex stent, or heparin-coated Jostent Flex stent. Pretreatment included aspirin and 10,000 IU Heparin.

The target lesion vessel diameter had to be between 2.0 and 2.6 mm. The primary endpoint was minimal lumen diameter at 6 months.

There were no significant differences in baseline patient characteristics or lesion distribution. In each study arm, about 80% of patients had multi-vessel disease. Angiographic results showed a near perfect match in reference diameter among the three groups (2.31 to 2.33 mm).

After intervention, there was a larger minimal lumen diameter, greater acute gain, and less residual stenosis in the stent groups.

At 6 months, there was a marginally significant benefit in minimal lumen diameter at 6 months favoring stent treatment. Minimal lumen diameter was 1.34 mm for balloon angioplasty, 1.47 mm for the heparin-coated stent, and 1.45 for the uncoated stent (P = 0.018).

A net gain difference favored the stent groups. However, late loss was identical in the stent groups and angioplasty group.

These results did not translate into a reduced rate of restenosis: 32% for balloon angioplasty, 25% for the uncoated stent, and 30% for the heparin-coated stent.

There were no statistically significant differences in number serious adverse events at 250 days. There were two deaths in both stent arms and none in the balloon angioplasty arm. Target vessel revascularization was somewhat higher in the balloon angioplasty arm. Event free survival at 250 days was 88% in both stent arms and 84% in the balloon angioplasty arm.

Taken together, these results suggest a borderline benefit in minimal lumen diameter in favor of stenting. Furthermore, there was no angiographic or clinical benefit of the heparin-coated Jostent Flex stent over the uncoated stent.