Prognostic value of exercise 201Tl tomography in patients treated with thrombolytic therapy during acute myocardial infarction
Related Experiment Videos
H A Dakik1, J J Mahmarian, K T Kimball
1Department of Medicine, Baylor College of Medicine, Houston, Tex, USA.
Insights
Quantitative exercise thallium-201 tomography offers crucial prognostic information for patients with acute myocardial infarction undergoing thrombolytic therapy, aiding long-term risk assessment.
Area of Science:
- Cardiology
- Nuclear Cardiology
- Diagnostic Imaging
Background:
- Myocardial perfusion scintigraphy is established for risk stratification in myocardial infarction patients on conventional therapy.
- Its utility in patients receiving thrombolytic therapy remains debated.
Purpose of the Study:
- To evaluate the prognostic value of quantitative exercise thallium-201 tomography in patients with acute myocardial infarction treated with thrombolysis.
- To compare the incremental prognostic information provided by tomography versus coronary angiography.
Main Methods:
- Seventy-one patients with acute myocardial infarction receiving thrombolytic therapy underwent exercise 201Tl tomography and coronary angiography.
- Cardiac events were tracked for a mean follow-up of 26 months.
Main Results:
- Fifteen percent showed ST-segment depression, while 38% had scintigraphic ischemia.
- Thirty-seven percent experienced cardiac events (death, reinfarction, heart failure, unstable angina).
- Left ventricular ejection fraction and ischemic perfusion defect size were significant joint predictors of risk by multivariate analysis.
Conclusions:
- Quantitative exercise 201Tl tomography provides significant, incremental long-term prognostic information.
- This technique improves risk stratification beyond clinical data and ejection fraction, without further benefit from angiography.
Background:
Although myocardial perfusion scintigraphy is of proven value in the risk stratification of patients with a recent myocardial infarction who receive conventional therapy, its value in patients undergoing thrombolytic therapy remains controversial.
Methods And Results:
Seventy-one patients who received thrombolytic therapy for acute myocardial infarction had exercise 201Tl tomography and coronary angiography before hospital discharge. Eleven (15%) of 71 patients had ischemic ST-segment depression during exercise, whereas 27 patients (38%) had scintigraphic ischemia. Twenty-five (37%) of 68 patients had a cardiac event consisting of either death (n = 2), recurrent myocardial infarction (n = 5), congestive heart failure (n = 7), or unstable angina (n = 11) during a follow-up of 26 +/- 18 months. Univariate predictors of cardiac events were as follows: Killip class (P = .04); left ventricular ejection fraction (P < .0005); total (P = .002) and ischemic (P < .0005) perfusion defect size; percent thallium lung uptake (P = .001); presence of infarct-zone redistribution (P = .02); and multivessel coronary artery disease (P = .01). By multivariate analysis, the significant joint predictors of risk were ejection fraction (P < .0005) and ischemic perfusion defect size (P = .005). The combination of ejection fraction and thallium tomography added significant incremental prognostic information to the clinical data, whereas angiography did not further improve a model that included clinical, ejection fraction, and tomographic variables.
Conclusions:
Quantitative exercise 201Tl tomography provides important incremental, long-term prognostic information in patients receiving thrombolytic therapy for acute myocardial infarction.