SPECT predicts restenosis potential in PTCA patients

Dec 19, 2001

Patients who undergo coronary stent implantation, and subsequently suffer from early myocardial perfusion defects, are more likely to have restenosis, according to a study in the latest issue of the Journal of Nuclear Medicine.

Researchers from the Hospital General Universitari Vall d’Hebron in Barcelona, Spain used 99mTc-tetrofosmin SPECT stress and rest studies to look at 30 patients who had undergone successful one-lesion percutaneous transluminal coronary angioplasty (PTCA).

"The primary objective of this study was to evaluate the incidence of early ischemic defects detected by simultaneous maximal subjective exercise and 99mTc-tetrofosmin SPECT (and) to determine the value of detecting early ischemic defects after coronary stent implantation in the prediction of late restenosis," wrote Dr. Josep Rodès-Cabau and co-authors (JNM, December 2001, Vol.42:12, pp. 1768-1772).

All patients, mean age 60, received an intravenous dose of 99mTc-tetrofosmin (220 MBq) 30-60 seconds before the end of the exercise test. Images were acquired one hour after administration of the radiotracer using an SP4 SPECT camera manufactured by now-defunct Israeli firm Elscint. SPECT findings were considered positive when mild, moderate, or severe defects were present on the stress images.

According to the results, 77% of the patients underwent follow-up angiography. Stenosis decreased from 68.5% of luminal diameter to 9.3% after stent implantation. Mild-to-moderate reversible myocardial defects were found in 17% of the patients. Angiographic restenosis occurred in three of four patients who had early ischemic defects, for a restenosis rate of 75%. In three of 19 patients who had no early ischemic defects, there was a 16% restenosis rate, the group reported.

"These early defects may be related to impairment of the microvascular response, microvascular stunning because of particulate embolization, or unapparent angiographic obstruction at or adjacent to the stent," they suggested.

By AuntMinnie.com staff writers
December 20, 2001