Purpose: Assess the myocardial and cerebral oxygenation reserve deficits utilizing the blood oxygen level dependent properties of Oxygenation-Sensitive MRI (OS-MRI) in heart failure patients.
Methods: Twelve heart failure patients (mean age 64±9 years; 36% female) and fourteen age-matched healthy volunteers (mean age 56±5 years; 64% female) underwent a CMR on a clinical 3T scanner (Skyra, Siemens, Erlangen, Germany). CMR functional parameters were obtained from standard SSFP cine images cine biplanar long-axis images. OS CMR images were obtained in a basal and mid-ventricular short-axis slice. The global Myocardial Oxygenation Reserve (MORE) was obtained from oxygenation sensitive SSFP short-axis cine images were acquired at resting baseline and continuously during a voluntary maximal breath-hold following a 60s period of hyperventilation. The cerebral BOLD images were obtained in the axial plane covering the full cerebrum. The global Cerebral Oxygenation Reserve (CORE) was obtained from subtraction images delineating the global signal intensity differences obtained on BOLD images in the grey matter of the brain.
Results: Heart failure patients (LVEF=40.98+/-14.18%) had a significantly lower left ventricular ejection fraction (LVEF) when compared to healthy controls (LVEF=69.46+/-6.79%) (p<0001). The percent-change in signal intensity in brain grey matter (CORE) and the global myocardium (MORE) after breathing maneuvers were significantly reduced in patients when compared to healthy controls (mean CORE 0.29+/-0.63 vs. 1.083+/-0.5047, p=0.0021, mean MORE 0.2497+/-3.495 vs. 4.451+/-4.15, p=0.0131) (Fig 1). There is a significant correlation between CORE and LVEF in heart failure patients with a Pearson correlation coefficient r=0.642, and a coefficient of determination r^2=0.4123, p=-0.032 (Fig 2).
Conclusion: The significant reduction of both cerebral and myocardial oxygenation reserves in heart failure patients when compared to healthy control subjects indicated that microvascular dysfunction of both the cerebrum and myocardium are present in heart failure patients. The presence of a significant correlation between LVEF and CORE suggests that microvascular dysfunction in the brain may be a result of chronic hypoperfusion.