Reduction of myocardial blood flow reserve in idiopathic dilated cardiomyopathy without overt heart failure and its relation with functional indices:an echo Doppler and positron emission study

Background Myocardial blood flow during pharmacological vasodilatation is depressed in patients with idiopathic dilated cardiomyopathy even in absence of overt heart failure; the extent of myocardial blood flow abnormalities is not predictable by left ventricular ejection fraction and diastolic dimensions. Aims To assess whether myocardial blood flow impairment in idiopathic dilated cardiomyopathy without overt heart failure can be related to Doppler-derived dP/dt and to echocardiographically determined left ventricular end systolic stress - which is linked to myocardial blood flow reserve in advanced disease. Methods 26 patients, New York Heart Association Class I-II, (LVEF 37.4W1.4%, left ventricular diastolic dimensions 62.6W0.9mm) underwent resting/dipyridamole 13N-NH3 flow positron emission tomography and an ultrasonic study. Regional myocardial blood flow values (ml minS1 gS1) were computed from positron emission tomography data in 13 left ventricular LV myocardial regions and averaged to provide mean myocardial blood flow and myocardial blood flow reserve, defined as dipyridamole/resting mean myocardial blood flow ratio. Results Resting myocardial blood flow was 0.686W0.045, dipyridamole myocardial blood flow 1.39W0.15 and myocardial blood flow reserve 2.12W0.2, lower than in controls (P<0.01). The ratio dP/dt was directly related to dipyridamole myocardial blood flow and myocardial blood flow reserve (rU0.552 and 0.703, P<0.005 and P<0.0001); no relation was found between myocardial blood flow and left ventricular ejection fraction, left ventricular diastolic dimensions, and left ventricular end systolic stress. Conclusions In idiopathic dilated cardiomyopathy patients without overt heart failure, the extent of myocardial blood flow reserve impairment is related to dP/dt but not to more classical indices of left ventricular function