Tl-201 scintigraphy in assessing the hemodynamic significance of isolated coronary artery stenoses

This study tests the hypothesis that the results of stress TL-201 scans (TL201) are related to the transtenotic pressure gradient (GRAD) of coronary stenoses independent of the luminal diameter narrowing (%NAR) seen at angiography. The 22 study patients (mean age 46 years, range 30-62, 2 female) had no prior myocardial infarction. Each underwent a symptom limited erect bicycle Tl201 off antianginal therapy, shortly before percutaneous transluminal coronary angioplasty (PTCA) for isolated left anterior descending coronary artery stenosis. The %NAR, GRAD (mmHG) at PTCA and severity of TL-201 defects (scaled 0-4) were independently evaluated and results compared. The GRAD (mean +- SD) is tabulated in relation to positive (+) or negative (-) TL201, and %NAR. In the 18 patients with <90% NAR, the GRAD was higher (P<.001) in those with +TL201 (64 +- 15) than those with -TL201 (33 +- 20) but their %NAR did not differ significantly (72 +- 14% vs 66 +- 19%; P=NS). At multiple regression analysis the severity of TL201 defect (P <.001) was a strong and %NAR (P <.05) a weak independent predictor for GRAD. TL201 adds valid information on the hemodynamic significance of a stenosis independent of %NAR. This may be of most value whenmore » %NAR is <90% and the clinical significance of the coronary stenosis is uncertain.« less