Initial evidence for the return of coronary vasoreactivity following the absorption of bioabsorbable magnesium alloy coronary stents

Aims: To investigate the endothelium independent coronary smooth muscle vasomotor function four months after implantation of magnesium alloy absorbable metal stents (AMS) as part of the Progress-AMS clinical trial (n=5), compared with a control group of patients implanted with permanent metal stents (PMS) (n=10) undergoing follow-up angiography, but who were free from angiographic restenosis. Methods and results: Quantitative coronary angiogram (QCA) using an automated edge detection system was performed before and after the administration of 2mg intracoronary isosorbide dinitrate (ISDN). The vessel diameter was measured at 0.2 mm intervals throughout the stented segments and a 1 cm proximal reference segment. The cross sectional area (CSA) was calculated before and after the ISDN, averaged and the percentage change measured. Reference segments demonstrated preserved vasomotor function in all cases: +13.28% (AMS) versus +17.15% (PMS), p=0.39. The mean percentage increase in CSA for the stented segment was +6.78% for the AMS versus 1.30% for PMS, p=0.003. Conclusion: These data demonstrate that four months after AMS implantation vasomotor function in reference segments is no different to that observed with PMS. However in contrast to PMS, within the AMS-stented segments there is demonstrable vasodilatation. These observations may have important implications for future stent design.