At low doses, dobutamine has potent inotropic, but limited chronotropic, ef
fects-properties that may be necessary for detection of hibernating myocard
ium. The efficacy of other catecholamines, which have more closely coupled
inotropic and chronotropic effects, for the detection of viable myocardium
is unknown. This study evaluated the efficacy of arbutamine, a catecholamin
e with potent throne-tropic effects, for the detection of viable myocardium
in a canine model of hibernating myocardium. Contractile reserve was asses
sed during stepwise arbutamine infusion (dosages of 2.5, 5, 10, 50, and 100
ng/kg/min) at 3 days (early) and 4 weeks (late) after coronary Ligation. S
egment shortening, wall thickening, and segmental wall motion were assessed
by sonomicrometry and echocardiography. After 4 weeks of occlusion, functi
onal recovery was assessed after revascularization During the early arbutam
ine study, the sensitivity for predicting functional recovery was highest a
t a dosage of 50 ng/kg/min, which also produced tathycardia. The sensitivit
y was 50% for segment shortening, 20% for wall thickening and 75% for wall
motion score: The late arbutamine study had improved sensitivity. The sensi
tivity was 100% for segment shortening, 80% for wall thickening, and 90% fo
r wall motion score at a dosage of 50 ng/kg/min. At the late arbutamine stu
dy, myocardial perfusion reserve in the ischemic zone of dogs with function
al recovery was only mildly reduced (2.0 versus 2.6 in nonischemic zones, P
= .53). After coronary occlusion, viable myocardium can be detected with h
igh doses of arbutamine that produce tachycardia. However, the sensitivity
of arbutamine stimulation for predicting functional recovery is low early a
fter occlusion, but it is improved by 4 weeks after occlusion with adequate
perfusion reserve.