A comparison of the mechanical performance characteristics of seven drug-eluting stent systems.

OBJECTIVES

Mechanical properties of drug eluting stents (DES) will be measured to provide comparable numerical data to assess deliverability, and thus clinical performance.

BACKGROUND

DES are routinely used in coronary interventions to reduce the rates of restenosis and target vessel revascularizations. Current research is primarily concerned with issues related to late stent thrombosis. However, mechanical properties of DES are a critical determinant of deliverability, and consequently the ultimate arbiter of their clinical performance.

METHODS

Mechanical properties (pushability, trackability, crossability) were measured under standardized in-vitro conditions. The vessel models were derived from typical vessel anatomy but adapted to the individual tests. Additionally, profile and bending forces of the stent segment of the delivery system were measured. Seven different commercially available balloon-expandable coronary DES systems were included. All stents were 3.0 mm diameter with a stent length from 14 to 18 mm.

RESULTS

The pushability expressed as the ratio of distal force at a specific proximal push force (4N) ranged between 38.66 and 18.53%. The trackability as the mean track-forces ranged from 0.551 N to 1.137 N. One stent system could not pass this test. The mean crossing forces at a 1.4 mm stenosis model ranged from 0.038 N up to 0.103 N. The mean crimped stent profiles ranged from 1.055 mm to 1.198 mm and the bending stiffness of the crimped stent was 17.22 to 47.20 Nmm2.

CONCLUSION

Better understanding of mechanical properties of DES shall improve tactile skills of the interventionists during PCI and to improve criteria for DES selection in specific clinical settings.