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. Exerc ise thallium scintigraphy is a useful method for the detection of rest enosis. In patients unable to exercise, dobutamine perfusion scintigra phy may represent a feasible alternative. However, its diagnostic accu racy in this clinical setting has not been evaluated. We studied 40 pa tients (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)-methoxy isobutyl 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 PTC A and was predicted on the basis of the occurrence of reversible perfu sion defects in the corresponding territories. Reversible perfusion de fects occurred in 20 of 29 arteries with and in 4 of 17 arteries witho ut restenosis. The sensitivity of dobutamine MIBI for the detection of restenosis in arteries with previous PTCA was 69% (CI = 56-82), the s pecificity 76% (CI = 64-89), the positive predictive value 83% (CI = 7 3-94), 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 d iagnosis of significant coronary stenosis (including arteries without previous PTCA) on a patient basis was 79% (CI = 67-92), the specificit y 82% (CI = 70-94) and accuracy 80% (CI = 68-92). The sensitivity of T c-99(m)-MIBI SPET was significantly higher than that of electrocardiog raphy (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 PT CA in patients unable to perform an exercise stress test.