Radionuclide techniques for evaluating dilated cardiomyopathy and ischemic cardiomyopathy

Objective To assess the clinical significance of radionuclide techniques in evaluating dilated cardiomyopathy (DCM) and ischemic cardiomyopathy (CAD-CM). Methods 28 patients with DCM and 55 patients with CAD-CM were studied. All patients underwent (99m) Tc-MIBI myocardial perfusion SPECT and (18) F-FDG myocardial metabolic PET. 78 patients had (99m) Tc-RBC radionuclide ventriculography and 68 patients had coronary angiography . Results The results of 23 patients (82%) with DCM showed mild and non-segmental distribution perfusion abnormalities. 52 patients with CAD-CM (95%) showed perfusion abnormalities that distributed along the coronary vessel territories. Significant perfusion defects were found in 4 patients with DCM (14%) and 45 patients with CAD-CM (82%) (P<0.01). The average perfusion score was 4.5±2.6 in DCM and 9.6±2.5 in CAD-CM and the area of diminished perfusion was significantly smaller in DCM than in CAD-CM (P<0.001). Two patients with DCM and 18 patients with CAD-CM had metabolic defects. The patterns of perfusion/metabolic imaging showed mismatch in most patients with CAD-CM but match in most patients with DCM. The LVEF in patients with DCM and CAD-CM was both decreased but the decreases were not statistically different between DCM and CAD-CM. The RVEF in patients with DCM was significantly lower than that in patients with CAD-CM (32.4%±13.9% vs 40.9%±15.4%, P<0.05). Conclusion The radionuclide techniques are helpful for distinguishing DCM from CAD-CM. The segmental perfusion abnormality and RVEF are the most important factors for differentiation of DCM from CAD-CM.