Key result
Abnormal stress SPECT linked to ~12-fold higher annual risk of death or MI vs normal.
Why the study?
The prognostic value of technetium-99m labeled tracers in myocardial perfusion imaging needed summarization due to differences from thallium-201 and increasing use in the US.
Does SPECT Tc-99m sestamibi imaging predict the risk of death or nonfatal MI in patients with ischemic heart disease?
Does SPECT Tc-99m sestamibi imaging predict the risk of death or nonfatal MI in patients with ischemic heart disease?
Effect estimate: 12-fold higher
Absolute Event Rate: 7.4% vs 0.6%
Normal stress SPECT sestamibi images in patients with stable chest pain syndromes indicate a very low risk of death or nonfatal MI, whereas abnormal images indicate an intermediate to high risk.
OBJECTIVES: This review summarizes the results of single-photon emission computed tomographic (SPECT) technetium-99m (Tc-99m) tracer imaging in patients with stable symptoms, patients with acute coronary syndromes, patients undergoing major non-cardiac surgery and patients with chest pain in the emergency department. BACKGROUND: Previous studies have examined the prognostic value of stress thallium imaging in several subsets of patients with ischemic heart disease. At present, >50% of myocardial perfusion studies are performed with technetium-labeled tracers in the United States. Furthermore, there is a shift from diagnostic to the prognostic utility of stress testing. There are important differences between technetium-labeled tracers and thallium-201. It is therefore important to review the prognostic value of technetium-labeled tracers. METHODS: We analyzed published reports in English on risk assessment using Tc-99m perfusion tracers. Results. The largest experience is in patients with stable symptoms, comprising >12,000 patients in 14 studies. In these patients, normal stress SPECT sestamibi images were associated with an average annual hard event rate of 0.6% (death or nonfatal myocardial infarction [MI]). In contrast, patients with abnormal images had a 12-fold higher event rate (7.4% annually). Both fixed and reversible defects are prognostically important, and quantitative analysis shows increased risk in relation to the severity of the abnormality. These results are similar to those obtained with thallium-201. CONCLUSIONS: Patients with stable chest pain syndromes and normal stress SPECT sestamibi images have a very low risk of death or nonfatal MI. It is highly unlikely that coronary revascularization can improve survival in such patients. Patients with abnormal images have an intermediate to high risk for future cardiac events, depending on the degree of the abnormality. Further prospective studies comparing aggressive medical therapy with coronary revascularization in these patients are warranted.
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Iskander et al. (1998) conducted a review in stable chest pain syndromes (n=12,000). Abnormal stress SPECT sestamibi images vs. Normal stress SPECT sestamibi images was evaluated on death or nonfatal myocardial infarction (12-fold higher). Abnormal stress SPECT sestamibi images in patients with stable symptoms were associated with a 7.4% annual rate of death or nonfatal MI, a 12-fold higher risk compared to normal images (0.6%).