Abstract 19661: Integrin Imaging for the Detection of Diffuse Myocardial Fibrosis in Patients with Hypertrophic Cardiomyopathy: Direct Comparison Between Single-Photon Emission Computer Tomography and Cardiovascular Magnetic Resonance The SCAR Study

Abstract

Background Hypertrophic cardiomyopathy (HCM) promotes diffuse myocardial collagen synthesis, disarray and hypertrophy. Cardiovascular magnetic resonance (CMR) imaging using late gadolinium enhancement (LGE) can detect focal fibrosis in HCM, although the injury process in HCM may be global and diffuse. αvβ3 is a vitronectin integrin receptor associated with fibroblasts and collagen synthesis. A ⁹⁹Technetium compound (^99mTc-NC100692) that binds with high affinity to αvβ3 has been developed. Thus, we hypothesize that ^99mTc-NC100692 could be used to detect focal and diffuse myocardial fibrosis in patients with HCM.

Methods 5 patients (62±11 years, 4 male) with a diagnosis of HCM from echocardiography were prospectively recruited. Patients underwent SPECT ^99mTc-NC100692 and CMR LGE imaging. Using a 17-segment model, ^99mTc-NC100692 images were visually assessed for myocardial uptake using a 3-point scale. LGE images were assessed for the presence or absence of enhancement per segment.

Results For the 5 patients, 85 segments were evaluated and all had some degree of ^99mTc-NC100692 uptake. Three patients had evidence for focal LGE in 9 segments. Of these 9 segments, 5 had matched high-grade ^99mTc-NC100692 uptake. One patient had strong apical ^99mTc-NC100692 uptake without any evidence of hypertrophy nor LGE. The remaining 79 segments had low-grade ^99mTc-NC100692 uptake with lack of evidence for LGE.

Conclusion Diffuse low-grade myocardial uptake of ^99mTc-NC100692 in patients with HCM may be suggestive of diffuse fibrosis. ^99mTc-NC10069 may serve as a marker of myocellular disarray although further studies are required to determine the specificity of ^99mTc-NC100692.