Background:
The differentiation between ischemic and nonischemic cardiomyopathy by noninvasive modalities is of clinical importance. whether thallium 201 single photon emission computed tomography (spect) could accurately distinguish the two groups remains unclear.
Methods and results:
Twenty-nine patients with chronic heart failure (left ventricular ejection fraction < or =40%), including fourteen patients with ischemic cardiomyopathy and fifteen patients with nonischemic dilated cardiomyopathy, underwent tl-201 spect. the stress protocols included treadmill exercise in 8 patients, dipyridamole in 6 patients, and dobutamine infusion in 15 patients. myocardial spect was interpreted with the use of a 17-segment model and 0- to 4-point scale system. patients with ischemic cardiomyopathy had higher summed stress defect scores (27.9 +/- 9.4 vs 20.6 +/- 8.9, p =.04), more fixed defect segments (5.9 +/- 2.9 vs 3.8 +/- 2.9, p =.05), and more moderate or severe perfusion defect segments on stress scan (7.2 +/- 2.0 vs 4.5 +/- 2.6, p =.004) than did those with nonischemic dilated cardiomyopathy. however, considerable overlap of the scan patterns between the two groups existed. moderate or severe perfusion defects on stress scan in at least 7 segments were noted in 71% of patients (10/14) with ischemic cardiomyopathy, as compared with 20% of patients (3/15) with nonischemic cardiomyopathy (p =.016).
Conclusions:
Assessment of tl-201 myocardial spect yields only modest value to distinguish nonischemic dilated cardiomyopathy from ischemic cardiomyopathy in patients with chronic heart failure. this technique cannot clearly differentiate individual patients.