Dobutamine Tc-99(m)-MIBI SPET myocardial perfusion scintigraphy in the prediction of restenosis after percutaneous transluminal coronary angioplasty in patients unable to perform an exercise stress test

After successful percutaneous transluminal coronary angioplasty (PTCA), restenosis occurs in a relatively high proportion of patients. Exercise thallium scintigraphy is a useful method for the detection of restenosis. In patients unable to exercise, dobutamine perfusion scintigraphy may represent a feasible alternative. However, its diagnostic accuracy in this clinical setting has not been evaluated. We studied 40 patients (29 males, 11 females) aged 57 +/- 9 years, at a mean of 185 +/- 80 days after successful PTCA with a high-dose dobutamine (up to 40 mu g kg(-1) min(-1)) stress test, in conjunction with Tc-99(m)-methoxyisobutyl isonitrile (Tc-99(m)-MIBI) single photon emission tomography (SPET). Significant restenosis was defined as greater than or equal to 50% luminal diameter stenosis of a coronary segment with previous PTCA and was predicted on the basis of the occurrence of reversible perfusion defects in the corresponding territories. Reversible perfusion defects occurred in 20 of 29 arteries with and in 4 of 17 arteries without restenosis. The sensitivity of dobutamine MIBI for the detection of restenosis in arteries with previous PTCA was 69% (CI = 56-82), the specificity 76% (CI = 64-89), the positive predictive value 83% (CI = 73-94), the negative predictive value 59% (CI = 45-73) and accuracy 72% (CI = 59-85). The overall sensitivity of Tc-99(m)-MIBI SPET for the diagnosis of significant coronary stenosis (including arteries without previous PTCA) on a patient basis was 79% (CI = 67-92), the specificity 82% (CI = 70-94) and accuracy 80% (CI = 68-92). The sensitivity of Tc-99(m)-MIBI SPET was significantly higher than that of electrocardiography (79 vs 38%, P < 0.005). It is concluded that dobutamine Tc-99(m)-MIBI SPET is a useful method for the detection of restenosis after PTCA in patients unable to perform an exercise stress test.