Non-invasive cardiac imaging plays a major role in the diagnosis, selection of therapy and assessment of prognosis in patients with heart failure. An overview of currently available techniques, including echocardiography, cardiac magnetic resonance imaging (CMR), nuclear innervations imaging, cardiac computed tomography (CT) and hybrid imaging was presented.
Shantanu Sengupta (Nagpur, India) discussed the role of echocardiography in clinical decision making. Echocardiography can be used as the first line tool for initial diagnosis and confirmation of heart failure, can evaluate global and regional left and right ventricular function, as well as important hemodynamic parameters. Doppler and TDI imaging are routinely used in assessing systolic and diastolic function as well as valvular disease in patients with HF. Echocardiography is a great bed-side tool for assessment of prognosis in HF patients. For example, hypertensive patients may show reduced longitudinal shortening despite normal wall thickening. Advances in echocardiography like 2D strain and vortex imaging helped to identify subclinical LV dysfunction in conditions like systemic hypertension. Similarly, assessment of myocardial mechanics has prognostic implications in patients receiving chemotherapy.
Pier Giorgio Masci (Pisa, Italy) presented the current and future role of CMR imaging in heart failure. The value of CMR in defining the etiology of HF was discussed. In particular, CMR is an accurate and cost-effective gatekeeper to invasive coronary angiography in discriminating between non-ischemic versus ischemic cardiomyopathy. The presentation also focused on the potential of CMR to refine the selection of candidates for cardiac resynchronization therapy thanks to an accurate quantification of intraventricular dyssynchrony and myocardial fibrosis by late gadolinium enhancement (LGE). Moreover, accumulated evidence supports the incremental value of LGE in predicting outcome of HF patients with respect to clinical and other imaging risk factors. Future developments include the CMR-based determination of extracellular volume fraction (ECV) determination for quantification of diffuse interstitial fibrosis. In light of excellent reproducibility and non-invasive nature of this technique, the serial quantification of ECV by CMR is highly desirable in phase II/III study testing novel anti-fibrotic therapies in HF. The use of perfluorocarbon probes and fluorine-19 CMR is a promising technique for in-vivo immune cells (macrophages and T cells) tracking and quantification gauging the inflammatory response in heart disease.
Jeroen Bax (Leiden, The Netherlands) in his talk on innovation and heart failure analyzed the role of cardiac sympathetic innervation imaging to assess prognosis and to predict HF predicting sudden cardiac death in heart failure patients. Myocardial innervation imaging using 123I-labeled metaiodobenzylguanidine (MIBG) scintigraphy can be used as a marker adrenergic neuron function. Low heart to mediastinum (H/M) ratio of MIBG uptake is associated with poor prognosis. In patients with left ventricular ejection fraction (LVEF) ≤35%, studied in the ADMIRE-HF study, a H/M ratio of ≥1.6 was associated with low risk, whereas a H/M ration of <1.6 was associated with high risk. LVEF and BNP levels have incremental prognostic value over the MIBG H/M ration in patients with HF and LVEF <30%. Regarding sudden cardiac death, 71% of patients in the Leiden registry had ischemic heart disease. In addition, late MIBG summed score can be used to predict the rate of appropriate ICD shocks or cardiac death. The defect on innervation images post-myocardial infarction is usually larger than the myocardial perfusion defect. The potential future application of MIBG imaging for the optimal selection of patients with heart failure for device therapy was also discussed.
Oliver Gaemperli (Zurich, Switzerland) reported on the role of cardiac CT and hybrid imaging in patients with heart failure. Cardiac hybrid and fusion imaging combine different imaging modalities, providing thus functional and anatomical information. The most commonly used combinations are SPECT/CT and PET/CT; however, use of PET/CMR, CT/3D Echo as well as 3D Echo/fluoroscopy in interventional cardiac procedures has been reported in academic centers. HF patients are usually complex patients in whom questions regarding the state of coronary arteries, presence of myocardial viability, presence of LV dyssynchrony and state of valves need to be addressed. CT and hybrid imaging can be a diagnostic tool and it can guide interventional procedures like revascularization, cardiac resynchronization therapy and structural heart valve disease interventions (TAVI, MitraClip, LAA occlusion in HF patients with atrial fibrillation). In particular, SPECT/CT and PET/CT may improve the diagnostic accuracy for ischemic heart disease in patients with HF, allow to determine functionally relevant coronary stenosis and help in guiding targeted revascularization procedures in this high risk population.