WASHINGTON — Sirolimus-eluting stents may induce coronary endothelial cell dysfunction in arterial segments that are distal to their placement, unlike conventional percutaneous coronary interventions, according to the results of a small study.
The antiproliferative effect of sirolimus-eluting stents inhibits neointimal hyperplasia, but this effect also may impair endothelial cell proliferation in the area distal to the stent. This could “potentially lead to coronary endothelial dysfunction,” said Dr. Kasai of the department of cardiology at Shinshu University, Matsumoto, Japan.
In a study that he presented at the annual meeting of the Society of Nuclear Medicine, Dr. Kasai and his colleagues included nine patients who underwent successful PCI for the treatment of stable angina or acute coronary syndrome after excluding patients with uncontrolled diabetes, symptoms of heart failure, or plasma brain natriuretic peptide levels greater than 100 pg/mL. Within 1 month after PCI, they quantitatively measured myocardial blood flow with 13N-ammonia PET at rest and then 30 minutes later during a cold pressor test.
The patients were instructed not to take any drugs during the morning of the testing, but all took aspirin to prevent thrombotic events. The investigators defined the left anterior descending coronary artery as the area distal to the stent.
Dr. Kasai and his associates identified seven coronary artery segments that received conventional PCI (plain balloon angioplasty or bare metal stent), six segments that received sirolimus-eluting stents (SES), and normal control segments in each patient that had less than 75% stenosis.
At rest, there was no difference in myocardial blood flow between the normal control and reperfused segments that were distal to the SES. Normal control and reperfused stent-distal segments with conventional PCI also had similar myocardial blood flow at rest. During cold pressor testing, myocardial blood flow did not differ significantly between normal control and stent-distal segments that had been reperfused with either conventional PCI or SES. But the percentage increase in myocardial blood flow from rest to stress with the cold pressor test (representing coronary endothelial function) was significantly lower in reperfused areas distal to SES (28%) than in normal control segments (47%). This was not seen in comparisons between reperfused areas distal to conventional PCI (64%) and normal control segments (54%).