Early recovery of coronary flow reserve after stent implantation as assessed by positron emission tomography

OBJECTIVES The aim of this study was to quantitatively evaluate myocardial flow reserve in patients early after coronary stent implantation using positron emission tomography. BACKGROUND Delayed restoration of coronary flow reserve after percutaneous transluminal coronary angioplasty (PTCA) has been observed using variety of techniques. Altered distal vasoregulation as well as residual stenosis have been considered possible explanations for this phenomenon. Although the implantation of stents may influence some of these mechanisms, little dat are available characterizing coronary flow reserve early after stent placement. METHODS In 14 patients 1.6 ± 0.6 days after stenting, N-13-ammoni positron emission tomographic studies were performed at rest and during adenosine-induced vasodilation. Myocardial blood flow was quantified using three-compartment model. Rest and stress flow data, as well as coronary flow reserve of stented vascular territories, were compared with that of remote areas. RESULTS The stenosis decreased from 72.1 ± 7.3% to 3.7 ± 6.7% after stent implantation. Coronary flow in the stented areas did not differ significantly from that in remote areas either at rest (76.1 ± 18.5 and 75.7 ± 17.7 ml/min/100 g, respectively), or during maximal vasodilation (205.5 ± 59.9 and 179.4 ± 47.4 ml/min/100 g, respectively). In addition, there was no significant difference in the calculated values of coronary reserve of these two regions (2.74 ± 0.64 and 2.43 ± 0.55, respectively). CONCLUSIONS The mechanical support of dilated arteries by stent not only restores the macroscopic integrity of epicardial arteries, but also results, in contrast to conventional PTC procedures, in early recovery of flow reserve.