Differential effects of drug-eluting stents on local endothelium-dependent coronary vasomotion

The aim of our study was to compare coronary vasomotion after implantation of a second-generation biolimus A9-eluting stent (BES) and of a sirolimus-eluting stent (SES).

Drug-eluting stents (DES) have been associated with impaired local coronary vasomotion, delayed endothelialization, and increased late thrombotic risk. New DES with different drugs, pharmacokinetics, and polymers have been developed.

Nineteen patients with a BES and 15 patients with a SES were studied 9 months after stent implantation. Endothelium-dependent and -independent coronary vasomotion were tested proximally and distally to the stent as well as at a reference segment during right atrial pacing at increasing heart rates. Quantitative coronary angiographic measurements were performed offline.

Of the patients with BES, 2 showed vasoconstriction with increased heart rate and 17 showed vasodilatation. Of the patients with a SES, 9 showed vasoconstriction while 6 showed vasodilatation. The SES showed significant vasoconstriction at both the proximal (-2.3 +/- 10% vs. 7.9 +/- 10%) and the distal (-5.4 +/- 9% vs. 6.1 +/- 8%) segments to the stent compared with the BES (p = 0.003 for proximal, p < 0.001 for distal segment). Endothelium-independent vasomotion after intracoronary nitrates did not differ significantly between the 2 groups (p = NS for proximal and distal segment).

Unlike the case with the SES, endothelium-dependent vasomotion at adjacent stent segments seems to be preserved after BES implantation. This result may be explained by the different drug release kinetics, DES design, or characteristics of polymer used in the stent system.