Abstract 10654: Absolute Hyperemic Myocardial Blood Flow is Impaired in Non-Ischemic Dilated Cardiomyopathy and is Related to the Severity of Left Ventricular Systolic Dysfunction

Abstract

Introduction: Myocardial perfusion reserve (MPR) is reduced in non-ischemic DCM. Microvascular ischemia may therefore be important in this condition. Since MPR is a ratio, absolute hyperemic myocardial blood flow (MBF) is a superior index of maximal perfusion. CMR perfusion imaging allows quantification of hyperemic MBF with high spatial resolution. We hypothesized that impaired hyperemic MBF can be detected in DCM by CMR and is related to the degree of LV systolic dysfunction (LVSD).

Methods: Consecutive DCM patients referred for CMR and age/sex matched healthy controls were prospectively enrolled. Exclusion criteria included IHD, diabetes and severe hypertension. Patients were classified as having severe LVSD or mild/moderate LVSD based on an LVEF cut-off of 35%. CMR first-pass perfusion imaging (1.5T) was performed during adenosine-induced hyperemia and at rest. Hyperemic and rest global MBF were quantified by Fermi function deconvolution.

Results: In total 67 patients (50 male, mean age 52 yrs, mean LVEF 37%) and 27 controls (17 male, mean age 46 yrs, mean LVEF 68%) were studied. CAD was excluded in 50 (75%) patients by angiography. The remainder (n=17) were aged <40 yrs, had no IHD risk factors and negative stress imaging tests. Severe LVSD was observed in 33 patients and mild/moderate LVSD in 34. Hyperemic MBF was significantly reduced in severe LVSD patients (mean 2.70 ± 0.89 ml/g/min) compared to those with mild/moderate LVSD (mean 3.56 ± 1.06 ml/g/min; p<0.001) and controls (mean 3.52 ± 0.66 ml/g/min, p<0.001) (Fig.1A). There was no difference in rest MBF between the 3 groups (Fig.1B). Hyperemic MBF significantly correlated with LVEF (r=0.46, p<0.001) in the DCM cohort.

Conclusions: Hyperemic MBF is impaired in DCM and correlates with LVSD. These findings support a role for microvascular ischemia in DCM. Further study is required to evaluate the mechanisms of hyperemic MBF impairment, its relationship to adverse remodeling and prognostic implications.