Abstract 3809: MR Quantification of Altered Subendocardial Myocardial Blood flow in Patients with Diastolic Heart Failure
Backgrounds: Exertional dyspnea is a common symptom in patients with diastolic heart failure (DHF), and subendocardial ischemia may be involved in the development of DHF. However, transmural distribution of myocardial blood flow (MBF) has not been evaluated in DHF patients.
PURPOSE: To determine if absolute MBF and transmural gradient of MBF are altered in patients with DHF by using a quantitative analysis of stress myocardial perfusion MRI.
METHODS: Twenty DHF patients (6 men, mean age 69±12 years, BNP 95±132 pg/ml) and 20 control subjects (15 men, mean age 66±7 years , BNP 26+/-24 pg/ml) were studied. Criteria of DHF included symptom of heart failure, LVEF of >0.5, LV diastolic dysfunction manifested by echocardiography and normal coronary arteries. Maximum volume (LAVmax) and fractional volume change of the left atrium(LA), as well as LV functions, were assessed by cine MRI. Gadolinium enhanced myocardial perfusion MR images were acquired during ATP stress and at rest using a saturation recovery balanced TFE MR sequence. Saturation correction of the blood signal was performed with a double bolus method. The LV myocardium was divided into 16 segments, and absolute MBF and myocardial perfusion reserve (MPR) in subepicardial and subendocardial sides of LV wall were determined by Patlak plots.
RESULTS: DHF patients demonstrated increased LAVmax index(49.5±13.7ml/m2 vs. 31.0±7.2ml/m2, p<0.001) and reduced fractional volume change of LA (41±9% vs. 49±6%, p<0.01) compared with controls. DHF and control groups had similar LV mass index(78±19g/m2 vs. 75±17g/m2, p=NS). Rest MBF averaged in 16 LV segments in DHF patients was not significantly different from that in control subjects (0.97±0.31ml/min/g vs. 0.99±0.25 ml/min/g, p=NS). However, stress MBF in subendocardial myocardium averaged in 16 segments was significantly lower in DHF patients than in controls (1.39±0.32 ml/min/g vs. 1.71±0.38 ml/min/g, p<0.01), resulting in significant reduction of subendocardial MPR in the DHF group (1.46±0.29 vs. 1.88±0.36, p<0.01).
CONCLUSION: The MBF in subendocardial myocardium was significantly impaired during vasodilator stress in patients with DHF, indicating that subendocardial ischemia may be closely related to the pathophysiology of DHF.