Relationship Between Synthetic and Conventional Extracellular Volume Fraction Calculations in Patients with Cardiac Amyloidosis: A Comparison of Published Formulas (RF_TH_198)

Thursday, January 30, 2025

2:20 PM – 2:30 PM East Coast USA Time

Location: Blue Room PreFunction - Kiosk 1

Presenting Author(s)

JN

Joseph D. Nguyen, BS

Medical Student
University of Virginia

Primary Author(s)

JN

Joseph D. Nguyen, BS

Medical Student
University of Virginia

Co-Author(s)

SH

Shivani K. Hanchate, MD

Resident
University of Virginia
Jeremy A. Slivnick, MD

Assistant Professor
University of Chicago
FM

Frank Medina, BSc

Medical Student
University of Chicago
MP

Maria Lourdes Posadas Martinez

Hospital Italiano de Buenos Aires, Argentina
SD

Santiago Decotto, MD

Faculty
Hospital Italiano de Buenos Aires, Argentina
CE

Cristhian Espinoza Romero, MD, MSc

Graduate Student
Instituto do Coração, Brazil
FF

Fabio Fernandes, MD, PhD

Heart Institute (InCor), University of Sao Paulo, Brazil
MC

Marcelo Campos Vieira, MD

Faculty
Instituto do Coração, Brazil
PD

Perez de Arenaza Diego, MD

Cardiologist
Hospital Italiano de Buenos Aires, Argentina
IB

Islamiyat Babs Animashaun, MD

Faculty
Atlantic Health System
Seth Uretsky, MD

Medical Director, Cardiovascular Imaging
Morristown Medical Center
VN

Vidya Nadig, MD

Cardiologist
Hartford Hospital
HW

Haonan Wang, PhD

Lead Scientist, Cardiac MR
GE Healthcare
VS

Varun Subashchandran, MD

Resident Physician
University of Chicago
AG

Akash Goyal, MD

Fellow
The Ohio State University
SS

Suzanne Smart, BSc, CCRP

Research Associate
The Ohio State University
Karolina M. Zareba, MD

Associate Professor
The Ohio State University
MA

Mohammad Abuannadi, MD

Assistant Professor
University of Virginia
PN

Patrick Norton, MD

Associate Professor
University of Virginia
Christopher M. Kramer, MD

Chief, Cardiovascular Division
University of Virginia Health
University of Virginia
Amit R. Patel, MD

Professor of Medicine
Division of Cardiology, University of Virginia Health System, Charlottesville, Virginia, USA.
CD

Cristiane C. De Carvalho Singulane, MD

Postdoctoral Researcher
University of Virginia Health System

Background: Extracellular volume fraction (ECV) has an important role in diagnosis, prognosis, and monitoring treatment response in cardiac amyloidosis (CA). ECV is derived from native and post-contrast T1-values of myocardium and blood after correcting for hematocrit (HCT). Recently, several formulas have been proposed that demonstrate a linear relationship between longitudinal relaxivity of blood and conventional (conv) blood HCT, allowing for the calculation of synthetic (syn) HCT, and thus synECV. In this study, we examine the performance of three different formulas for calculating synECV from synHCT to determine which formula correlates best with convECV.

Methods: This was a cross-sectional, multi-center study of 87 subjects with CA who underwent CMR with T1 mapping (79.3% 1.5T) and had a HCT value from within 1 month of the CMR. The Modified Look-Locker (MOLLI) 5s(3s)3s protocol was used to perform native and post-contrast T1 mapping. ConvECV was calculated using the blood sample HCT. SynECV was measured using synHCT, which was calculated using three different formulas: one by Treibel et al. using the LV blood pool (Treibel) adjusted for magnetic field strength, and two by Chen et al. using the LV (LV Chen) and RV (RV Chen) blood pools, respectively, adjusted for magnetic field strength and patient sex. Contours were drawn to define blood pools on native and post-contrast mid-ventricular short-axis images. Analysis was performed offline via commercially available vendor-independent software (SuiteHeart, NeoSoft). Anemia was defined as convHCT < 41% in males and < 36% in females. Correlations were calculated using Spearman Rank correlation coefficient (ρ). Statistical comparison of correlations was done using Fisher’s z.

Results: Baseline characteristics and CMR parameters are listed in table 1. There was a moderate correlation between convHCT and synHCT via Treibel (ρ=0.38, p=0.0003), LV Chen (ρ=0.39, p=0.0002), and RV Chen (ρ=0.28, p=0.009) formulas. There was a strong correlation between convECV and synECV via Treibel (ρ=0.91, p< 2.2e-16), LV Chen (ρ=0.89, p< 2.2e-16), and RV Chen (ρ=0.85, p< 2.2e-16) formulas (Figure 1A-C). There was no significant difference in the strengths of these correlations (ρ) in all patients (Treibel vs LV Chen: p=0.450; Treibel vs RV Chen: p=0.051; LV Chen vs RV Chen: p=0.230), patients with anemia (0.91 vs 0.89, p=0.495; 0.91 vs 0.81, p=0.055; 0.89 vs 0.81, p=0.216, Figure 2A/B/C), or patients without anemia (0.96 vs 0.92, p=0.127; 0.96 vs 0.92, p=0.101; 0.92 vs 0.92, p=0.908, Figure 2D/E/F). Correlation was stronger in non-anemic patients, compared to anemic patients, when the RV Chen (0.92 vs 0.81, p=0.041) formula was used.

Conclusion: Multiple established formulas for calculating synthetic ECV show an excellent correlation with conventional ECV in patients with cardiac amyloidosis. It remains to be seen whether synECV can be used as an alternative to convECV to monitor disease progression and perform risk stratification in patients with cardiac amyloidosis.