Longitudinal compression behaviour of coronary stents: a bench-top comparative study.

AIMS: The aim of this study was to characterise the coronary stent longitudinal resistance of new coronary stents under worst case clinical crossing simulated configurations.

METHODS AND RESULTS: Six coronary balloon-expandable stents were evaluated using two different tests. The first was a direct parallel plates longitudinal crush resistance test: it was conducted on stents deployed to 3 mm diameter, and three samples of each model were used. The second was performed by tracking over the wire and deploying the stents in two types of coronary model: good and malapposition models. Two samples of each model were used for this test. After deployment, a PTCA balloon was advanced over the wire. For each stent, the force required for balloon tracking and the stent shortening were recorded. In the first crush test, three out of six stent models demonstrated higher longitudinal crush rates compared to the Resolute Integrity (Medtronic, Minneapolis, MN, USA): PROMUS Element™ (Boston Scientific, Natick, MA, USA) p<0.0001, Coroflex® Blue (B. Braun, Melsungen, Germany) p<0.0001, and Orsiro (Biotronik, Berlin, Germany) p=0.038. In the simulation test, there were no statistical differences when comparing all good and malapposition groups.

CONCLUSIONS: Lower resistance to mechanical longitudinal compression of some stents did not correlate to significantly higher crush rates in simulated clinical conditions. Nevertheless, it would be useful for cardiologists to be aware of the actual mechanical characteristics of new stents to take them into account and thus minimise longitudinal compression during difficult stent implantations.