Advances in SPECT and PET for the management of heart failure

In population studies including patients with new onset heart failure, progressive heart failure appears to be the single most common cause of death (52%), with sudden death accounting for only 22% of deaths within the first 6 months of diagnosis.1 Studies published in recent years have shown that nuclear cardiology, both single photon emission computed tomography (SPECT) and positron emission tomography (PET), has the potential to provide clinically useful information enabling better stratification and optimal choice of treatment for patients with heart failure. Older age, greater functional impairment, poorer systolic function of the left ventricle, lower serum sodium, poorer renal function, broader QRS complex, lower blood pressure, and inability to tolerate disease modifying drugs such as angiotensin converting enzyme (ACE) inhibitors, are generally associated with a poorer prognosis and are mentioned in guidelines for heart failure management.2 There is a pressing need for improved risk stratification for patients developing heart failure, with the goal of better identification of those for whom more aggressive therapy is likely to be beneficial. ### Cardiac autonomic dysfunction From a pathophysiological viewpoint, there is increased sympathetic activity in the hearts of patients with congestive heart failure, which is a generalised rather than a regional phenomenon, and contributes to the remodelling process of the whole left ventricle (figure 1). The myocardium of patients with systolic heart failure is characterised by a significant reduction of pre-synaptic norepinephrine (noradrenaline) uptake and post-synaptic β-adrenoceptor density.3 Figure 1 Increased cardiac sympathetic activity in heart failure. A reduced cardiac output entails decreased inhibitory inputs (baroreceptor afferent fibres) and increased excitatory inputs (mechanoreceptor afferent fibres) to the dorsolateral medulla. This results in increased cardiac sympathetic activity and reduced vagal output. Courtesy of Ornella Rimoldi MD. #### Imaging pre-synaptic norepinephrine handling Metaiodobenzylguanidine (MIBG) is a structural analogue of norepinephrine that shares the same uptake and storage mechanisms as norepinephrine. MIBG can be …