Relative Apical Sparing of Myocardial Longitudinal Strain Is Explained by Regional Differences in Total Amyloid Mass Rather Than the Proportion of Amyloid Deposits

Paco E. Bravo, Kana Fujikura, Marie Foley Kijewski, Michael Jerosch-Herold, Sophia Jacob, Mohamed Samir El-Sady, William Sticka, Shipra Dubey, Anthony Belanger, Mi Ae Park, Marcelo F. Di Carli, Raymond Y. Kwong, Rodney H. Falk, Sharmila Dorbala

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

Objectives: This study sought to test whether relative apical sparing (RELAPS) of left ventricular (LV) longitudinal strain (LS) in cardiac amyloidosis (CA) is explained by regional differences in markers of amyloid burden (18F-florbetapir uptake by positron emission tomography [PET] and/or extracellular volume fraction [ECV] by cardiac magnetic resonance (CMR)]. Background: Further knowledge of the pathophysiological basis for RELAPS can help understand the adverse outcomes associated with apical LS impairment. Methods: This was a prospective study of 32 subjects (age 62 ± 7 years; 50% males) with light chain CA. All subjects underwent two-dimensional echocardiography for LS estimation and 18F-florbetapir PET for quantification of LV florbetapir retention index (RI). A subset also underwent CMR (n = 22) for ECV quantification. Extracellular LV mass (LV mass*ECV) and total florbetapir binding (extracellular LV mass*florbetapir RI) were also calculated. All parameters were measured globally and regionally (base, mid, and apex). Results: There was a significant base-to-apex gradient in LS (−7.4 ± 3.2% vs. −8.6 ± 4.0% vs. −20.8 ± 6.6%; p < 0.0001), maximal LV wall thickness (15.7 ± 1.9 cm vs. 15.4 ± 2.9 cm vs. 10.1 ± 2.4 cm; p < 0.0001), and LV mass (74.8 ± 21.2 g vs. 60.8 ± 17.3 g vs. 23.4 ± 6.2 g; p < 0.0001). In contrast, florbetapir RI (0.089 ± 0.03 μmol/min/g vs. 0.097 ± 0.03 μmol/min/g vs. 0.085 ± 0.03 μmol/min/g; p = 0.45) and ECV (0.53 ± 0.08 vs. 0.49 ± 0.08 vs. 0.49 ± 0.07; p = 0.15) showed no significant base-to-apex gradient in the tissue concentration or proportion of amyloid infiltration, whereas markers of total amyloid load, such as total florbetapir binding (3.4 ± 1.7 μmol/min vs. 2.8 ± 1.5 μmol/min vs. 0.93 ± 0.49 μmol/min; p < 0.0001) and extracellular LV mass (40.0 ± 15.6 g vs. 30.2 ± 10.9 g vs. 11.6 ± 3.9 g; p < 0.0001), did show a marked base-to-apex gradient. Conclusions: Segmental differences in the distribution of the total amyloid mass, rather than the proportion of amyloid deposits, appear to explain the marked regional differences in LS in CA. Although these 2 matrices are clearly related concepts, they should not be used interchangeably.

Original languageEnglish (US)
Pages (from-to)1165-1173
Number of pages9
JournalJACC: Cardiovascular Imaging
Volume12
Issue number7
DOIs
StatePublished - Jul 2019
Externally publishedYes

Keywords

  • amyloidosis
  • extracellular volume fraction
  • florbetapir
  • longitudinal strain
  • wall thickening

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging
  • Cardiology and Cardiovascular Medicine

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