Thallium-201 Myocardial Imaging in Patients with Coronary Artery Disease: Comparison of Intravenous Adenosine and Oral Dipyridamole

Abstract

OBJECTIVE:

To compare thallium-201 (²⁰¹Tl) myocardial perfusion imaging following intravenous adenosine and oral dipyridamole.

DESIGN:

Open-label, randomized, comparison.

SETTING:

Outpatient, university-affiliated clinic.

PATIENTS:

Fifteen patients with angiographically documented coronary artery disease.

INTERVENTIONS:

Planar ²⁰¹Tl myocardial perfusion imaging following both intravenous adenosine 140 μg/kg/min for six minutes and oral dipyridamole suspension 300 mg.

MAIN OUTCOME MEASURES:

A comparison between adenosine and dipyridamole was made in the following areas: concordance in interpretation of ²⁰¹Tl scintigrams, cardiac and noncardiac ²⁰¹Tl uptake and clearance, hemodynamic and electrocardiographic changes, and adverse effects.

RESULTS:

The scintigraphic studies showed perfusion defects in 13 patients (87 percent) after dipyridamole and in 15 patients (100 percent) after adenosine. ²⁰¹Tl uptake and clearance were quantitated in nine myocardial segments and in four extracardiac segments in each patient. ²⁰¹Tl uptake was not significantly different between adenosine and dipyridamole studies in most cardiac regions. Extracardiac ²⁰¹Tl uptake was significantly less in the liver and splanchnic regions following adenosine compared with dipyridamole. ²⁰¹Tl clearance was not significantly different following adenosine and dipyridamole except in the anterolateral region in the anterior view. Hemodynamic changes following administration of intravenous adenosine and oral dipyridamole were not significantly different. Adverse effects were more common with adenosine than with dipyridamole. Adverse effects with adenosine were transient; however, adverse effects with dipyridamole were prolonged and required reversal with aminophylline in 2 patients. No patients required termination of the adenosine infusion or administration of aminophylline.

CONCLUSIONS:

These preliminary data suggest that adenosine ²⁰¹Tl imaging may be a useful alternative to dipyridamole ²⁰¹Tl imaging. Although adenosine produces more frequent adverse effects, they are generally better tolerated than those associated with dipyridamole.