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Dobutamine thallium-201 tomography for evaluating patients with suspected coronary artery disease unable to undergo
J T Hays1, J J Mahmarian, A J Cochran
1Department of Medicine, Baylor College of Medicine, Houston, Texas.
Insights
High-dose dobutamine infusion combined with thallium tomography is a safe and accurate method for diagnosing coronary artery disease (CAD) in patients unable to undergo exercise or vasodilator stress testing.
Area of Science:
- Cardiology
- Nuclear Cardiology
- Diagnostic Imaging
Background:
- Dobutamine increases myocardial oxygen demand, creating blood flow heterogeneity beneficial for detecting coronary artery disease (CAD).
- Assessing the feasibility, safety, and accuracy of high-dose dobutamine infusion with thallium-201 SPECT is crucial for patients unable to perform standard stress tests.
Purpose of the Study:
- To evaluate the diagnostic accuracy of high-dose dobutamine infusion combined with thallium-201 SPECT.
- To assess the safety and feasibility of this method in patients unable to perform exercise or vasodilator stress testing.
Main Methods:
- 144 patients received intravenous dobutamine at incremental doses up to 40 mcg/kg/min.
- Thallium-201 was injected at peak infusion, followed by SPECT imaging at 5-10 minutes and 4 hours.
- Coronary angiography was performed in 84 patients to validate findings.
Main Results:
- Dobutamine significantly increased heart rate, systolic blood pressure, and rate-pressure product.
- While 75% experienced side effects, most tolerated high dobutamine doses; common side effects included chest pain and palpitations.
- Dobutamine SPECT demonstrated high sensitivity (86%) and specificity (90%) for diagnosing CAD, identifying 78% of severe stenoses.
Conclusions:
- High-dose dobutamine infusion with thallium tomography is a well-tolerated and accurate diagnostic tool.
- This method provides a viable alternative for diagnosing CAD in patients unsuitable for traditional stress tests.
Objectives:
The aim of this study was to assess the feasibility, safety and diagnostic accuracy of a high dose dobutamine infusion in conjunction with thallium-201 single-photon emission computed tomography in 144 patients (72 men and 72 women with a mean age of 65 +/- 10 years) unable to perform exercise or pharmacologic vasodilator stress testing.
Background:
Dobutamine increases myocardial oxygen consumption by increasing heart rate, contractility and arterial blood pressure. In addition, it causes myocardial blood flow heterogeneity and thus may be a useful stress for noninvasive detection of coronary artery disease.
Methods:
Dobutamine was administered intravenously at incremental doses of 5, 10, 20, 30 and up to 40 micrograms/kg per min at 3-min intervals. After 1 min of the maximal dose, 3 mCi of thallium-201 was injected and the infusion was continued for an additional 2 min. Thallium-201 tomography was performed 5 to 10 min after termination of the infusion and 4 h later. The images were visually assessed for the presence and vascular location of perfusion defects and the extent of thallium redistribution. Coronary angiography was performed in 84 patients, with a > 50% stenosis considered significant.
Results:
Dobutamine significantly (p = 0.0001) increased the heart rate (from 75 +/- 14 beats/min to 120 +/- 23 beats/min), systolic blood pressure (from 136 +/- 23 mm Hg to 148 +/- 35 mm Hg) and the rate-pressure product (from 10,144 +/- 2,517 to 17,858 +/- 4,349) from baseline to peak infusion rate, respectively. Most patients (75%) experienced side effects during the infusion, but 74% tolerated a dobutamine dose of 40 micrograms/kg per min and 97% a dose of 30 micrograms/kg per min. The more common side effects were typical (26%) and atypical (5%) chest pain, palpitation (29%), flushing (14%), headache (14%) and dyspnea (14%). The overall sensitivity of dobutamine tomography was 86% in the patients who underwent coronary angiography and 84% in those with single-vessel, 82% in those with double-vessel and 100% in those with triple-vessel disease. Seventy-eight percent of vessels with severe (> or = 70%) stenoses were identified with dobutamine tomography. The specificity of dobutamine tomography was 90% for patients and 86% for individual vessels.
Conclusions:
A high dose dobutamine infusion in conjunction with thallium tomography appears to be a well tolerated and accurate method for diagnosing coronary artery disease in patients unable to perform exercise or vasodilator pharmacologic stress testing.