Safety of pharmacological [intravenous dipyridamole] stress for thallium-201 perfusion imaging in patients with coronary artery disease unable to exercise

ABSTRACT

Exercise Thallium-201 myocardial perfusion imaging is a sensitive technique for detection of CAD. However, in patients unable to perform exercise pharmacological stress with intravenous dipyridamole can be used to dilate coronaries. Out of 125 patients [21 men and 104 women; mean age 52.03 years] evaluated, 110 were considered to be unable to perform adequate stress by their physician while remaining 15 had LBBB. One hundred and seven patients had chest pain with or without a remote MI while 18 individuals were clinically asymptomatic but had ECG abnormalities. Intravenous dipyridamole was administerted at a rate of 0.142 mg/kg/min for 4 min. After 3 min an i.v. bolus of T1-201 was given. Diffuse or occipital headache of mild to moderate intensity occurred in 50 [40%] cases; 39 patients experienced chest pain and had either a positive thallium scan [26 cases] suggestive of CAD or a normal thallium study [15 cases]. Complete relief from dipyridamole induced symptoms was brought by i.v. aminophylline and sublingual nitrate in 51 of 54 cases [94%] and 11 of 18 [61%] respectively. We, therefore, conclude 1] i.v. dipyridamole-thallium scintigraphy offers a safe, effective and reliable method for evaluating CAD in those who are unable to perform adequate exercise and 2] parenteral aminophylline is very effective antidote to dipyridamole