Multiparametric cardiovascular magnetic resonance for the assessment of cardiac function and metabolism in hypertrophy and heart failure

Both hypertrophied and failing hearts are characterised by pathological left ventricular (LV) remodelling, impaired myocardial energy status and alteration in substrate metabolism. Cardiac magnetic resonance imaging (CMR) and magnetic resonance spectroscopy (MRS) are powerful tools in the characterisation of these disease conditions. More recent techniques have allowed assessment of myocardial steatosis using 1H-MRS and tissue oxygenation using blood oxygen level dependent (BOLD) CMR. In hypertrophy and heart failure, studies on steatosis and the relationship with other parameters such as myocardial function and fibrosis, especially in humans are limited. I therefore investigated the presence of steatosis in severe aortic stenosis (AS) and dilated cardiomyopathy (DCM), and further assessed its relation to contractile function. This study found that myocardial triglyceride (TG) content is increased in both symptomatic and asymptomatic AS patients (lipid/water ratio 0.89±0.42% in symptomatic AS; 0.75±0.36% in asymptomatic AS vs. controls 0.45±0.17%, both p Additionally, although the hypertrophied heart is characterised by impaired perfusion, it is unknown if this is severe enough to translate into tissue deoxygenation and ischaemia. I assessed this by using adenosine vasodilator stress test and BOLD-CMR in patients with severe AS. It was found that AS patients had reduced perfusion (myocardial perfusion reserve index-MPRI 1.0±0.3 vs. controls 1.7±0.3, p Overall, the work in this thesis supports the powerful role of CMR in assessing LV function and elucidating metabolic mechanisms in the hypertrophied and failing heart.