Radionuclide assessment of regional differences in left ventricular wall motion and myocardial perfusion in idiopathic dilated cardiomyopathy

Regional variations in left ventricular contractility and myocardialperfusion are frequent in idiopathic dilated cardiomyopathyand might result from an increase in left ventricular wall stressresponsible for regional wall motion abnormalities. The aimof the study was to perform radionuclide studies in patientswith idiopathic dilated cardiomyopathy to assess regional leftventricular wall motion and myocardial perfusion abnormalitiesin this myocardial disease. We studied 29 men referred withidiopathic dilated cardiomyopathy and normal coronary angiograms.Rest radionuclide left ventriculography and exercise thallium-201tomography were performed in all patients. The thallium-201tomograms were divided into 20 segments for each patient. Meanleft ventricular ejection fraction was 27±11%; 17 patientshad diffuse hypokinesia (mean left ventricular ejection fraction:24±9%) and 12 patients had predominant regional hypokinesia(mean left ventricular ejection fraction: 32±12%). Ofall 580 tomographic segments, 186 had a reduction of thallium-201uptake at exercise. Among them, reversibility was found in 53%.On the whole, 68% (158/232) of anterior, inferior and apicalsegments had a perfusion abnormality, compared with 8% (28/348)of septal and lateral segments (P<0.0001). Left ventricular wall motion and myocardial perfusion abnormalitiesare heterogeneous and not evenly distributed in dilated cardiomyopathy.The alterations are predominant on the myocardial regions delineatingthe antero-posterior axis of the left ventricle. These findingssuggest the possible role of increased left ventricular wallstress on this axis.