DOBUTAMINE TC-99M-MIBI SINGLE-PHOTON EMISSION TOMOGRAPHY - NON-EXERCISE-DEPENDENT DETECTION OF HEMODYNAMICALLY SIGNIFICANT CORONARY-ARTERY STENOSES

Dobutamine pharmacological stress testing in conjunction with techneti um-99m methoxyisobutylisonitrile single-photon emission tomography (MI BI SPET) may be a useful alternative to convential exercise stress MIB I SPET for the detection and localisation of coronary artery stenoses. Therefore, 35 patients with stenoses (greater-than-or-equal-to 50% di ameter reduction) of one or more coronary arteries were selected for d obutamine MIBI SPET. Each patient underwent MIBI injection at rest and during dobutamine infusion with incremental doses (5, 10, 15 and 20 m ug kg-1 min-1). A conventional exercise stress test (EST) was performe d in all patients. Peak double product during steady-state dobutamine infusion (18 200 +/- 4200 mmHg min-1) was lower (P = 0.0001) than duri ng EST (21 700 +/- 4900 mmHg min-1). Image quality was good in all but one patient, who had to be excluded from data analysis due to excessi ve hepatobiliary MIBI activity. Dobutamine-induced perfusion abnormali ties were observed in 30/34 MIBI SPET studies, resulting in an overall detection rate for coronary artery disease of 88%. A pathological EST was observed in 23134 patients (68%). The detection rate of individua l coronary artery stenoses was 85% (28/33) for stenosess with a severe diameter reduction (> 70%) and 50% (12/24) for stenoses with a modera te diameter reduction (greater-than-or-equal-to 50-70%). In particular , sensitivity and specificity for the detection of moderate and severe stenoses (greater-than-or-equal-to 50%) were 75%/100% for left anteri or descending, 67%/95% for left circumflex and 67%/69% for right coron ary artery stenoses. Dobutamine MIBI SPET is a well-tolerated, non-exe rcise-dependent test for detection and localisation of haemodynamicall y significant coronary artery stenoses. The use of dobutamine allows a stepwise increase in pharmacological stress similar to EST and is esp ecially useful in patients who are unable to exercise.