Imaging for assessment of sudden death risk: current role and future prospects

Abstract

Sudden cardiac death (SCD) remains a major public health problem and there is an urgent need to maximize the impact of primary prevention using the implantable defibrillator. While implantable defibrillators are of utility for prevention of SCD, current methods of selecting candidates have significant shortcomings. Major advancements have occurred in the field of cardiac imaging, with significant potential to identify novel cardiac substrates for improved prediction. While assessment of the left ventricular ejection fraction remains the current major predictor, it is likely that several novel imaging markers will be incorporated into future risk stratification approaches. The goal of this review is to discuss the current status and future potential of cardiac imaging modalities to enhance risk stratification for SCD.

Keywords: Cardiac imaging; Risk stratification; Sudden cardiac death.

Figure 1

Framework of current and future imaging modalities for sudden cardiac death risk stratification.

Figure 2

Current and future imaging modalities for sudden cardiac death risk stratification depending on aetiologies of heart disease. Vulnerable plaque imaging, molecular imaging, and postmortem imaging will be incorporated in future sudden cardiac death risk stratification.

Figure 3

¹²³I-mIBG and ^99mTc-sestamibi SPECT images of a patient who received ICD shocks. There are neuronal/perfusion mismatching defects involving the inferior, inferolateral, and apical walls; there is a matched defect in the anterior wall. HLA, horizontal long axis; ICD, implantable cardioverter defibrillator; mIBG, metaiodobenzylguanidine (¹²³I-mIBG); MIBI, ^99mTc-sestamibi; SA, short axis; SPECT, single-photon emission computed tomography. Reprinted from Ji and Travin.

Figure 4

A short-axis view of cardiac MR in a 50-year-old male with non-ST-elevation myocardial infarction from thrombotic occlusion of a septal perforator. There is a very heterogeneous infarct (arrow). Grey zone, defined as a mixture of scar/fibrosis and viable myocytes in the infarct border zones, is associated with increased susceptibility to ventricular arrhythmia. MR, magnetic resonance.

Figure 5

Non-invasive CMR of carotid plaque macrophages using dextran-coated iron oxide magnetic nanoparticles (MNPs). (A) Preinjection CMR (axial 3-mm section) of a patient 4.5 months after presentation with amaurosis fugax. (B) Thirty-six hours after agent injection, focal signal loss evolves within the plaque (arrow). (C) After endarterectomy, a collagen van Gieson stain depicts a thin fibrous cap (black arrowhead) overlying a large lipid core (white arrowhead; ×1.5 magnification). (D) Perls stain for iron and an immunohistochemical stain for macrophages confirm colocalization of MNPs (blue) with macrophages (brown; ×40 magnification). Reproduced from Trivedi et al. (Copyright 2004). CMR, cardiac magnetic resonance.