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Utility of various radionuclide techniques for distinguishing ischemic from nonischemic dilated cardiomyopathy
D B Glamann1, R A Lange, J R Corbett
1Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas 75235.
Insights
Differentiating ischemic from nonischemic dilated cardiomyopathy using radionuclide ventriculography and thallium-201 imaging is unreliable. Many patients with nonischemic cardiomyopathy exhibit abnormalities typically associated with ischemic heart disease.
Area of Science:
- Cardiology
- Nuclear Cardiology
- Diagnostic Imaging
Background:
- Distinguishing between ischemic and nonischemic (idiopathic) dilated cardiomyopathy presents clinical challenges.
- Radionuclide ventriculography and thallium-201 scintigraphy are commonly employed for noninvasive differentiation.
- Traditional indicators of ischemic heart disease include left ventricular (LV) regional asynergy, LV systolic dysfunction with normal right ventricular function, and perfusion abnormalities.
Purpose of the Study:
- To evaluate the frequency of these abnormalities in patients diagnosed with nonischemic dilated cardiomyopathy.
- To assess the reliability of current noninvasive imaging techniques in differentiating between ischemic and nonischemic cardiomyopathy.
Main Methods:
- Seventy-six patients with confirmed nonischemic dilated cardiomyopathy were studied.
- Radionuclide ventriculography was performed on 75 patients.
- Provocative thallium-201 perfusion imaging was conducted on 17 patients.
Main Results:
- Left ventricular (LV) regional wall motion abnormalities were observed in 48% of patients.
- LV systolic dysfunction without concurrent right ventricular dysfunction was present in 54% of patients.
- Reversible or fixed exercise-induced thallium-201 perfusion abnormalities were detected in 94% of the studied patients.
Conclusions:
- Radionuclide ventriculography and thallium perfusion imaging are not reliable for differentiating ischemic from nonischemic dilated cardiomyopathy.
- The presence of LV segmental wall motion abnormalities, selective LV systolic dysfunction, and segmental perfusion abnormalities in nonischemic cardiomyopathy limits the diagnostic utility of these tests.
Background:
Clinically, ischemic and nonischemic (idiopathic) dilated cardiomyopathy may be difficult to distinguish. Radionuclide ventriculography and exercise testing with thallium-201 scintigraphy are often used in an attempt to differentiate them noninvasively. With these techniques, the presence of (1) left ventricular (LV) regional asynergy, (2) depressed LV systolic function with normal right ventricular function, and/or (3) thallium-201 perfusion abnormalities traditionally has been regarded as evidence of ischemic heart disease. We assessed the incidence with which these abnormalities occur in patients with nonischemic-dilated cardiomyopathy.
Methods:
Seventy-six patients (45 men, 31 women, aged 18 to 75 years) with invasively proven nonischemic-dilated cardiomyopathy underwent radionuclide ventriculography (n = 75) and provocative thallium-201 perfusion imaging (n = 17).
Results:
Regional LV wall motion abnormalities were noted in 48% of patients, and 54% had LV systolic dysfunction without concomitant right ventricular dysfunction. Reversible and/or fixed exercise-induced thallium-201 perfusion abnormalities occurred in 94% of the patients studied.
Conclusions:
Radionuclide ventriculography and exercise testing with thallium perfusion imaging cannot be used reliably to differentiate ischemic from nonischemic dilated cardiomyopathy, since many patients with the latter have radionuclide evidence of LV segmental wall motion abnormalities, selective LV systolic dysfunction, and segmental perfusion abnormalities.