P876Cardiac magnetic resonance based feature-tracking myocardial strain analysis in MINOCA patients
Authors: Szabo L , Horvath V , Dohy Z , Czimbalmos C , Toth A , Suhai F , Barczi G , Becker D , Merkely B , Vago H 
Published: October 2019

Abstract

The diagnostic performance of cardiac magnetic resonance (CMR) based deformation imaging (feature tracking - FT) has been demonstrated in various groups of patients including acute myocardial infarction and acute myocarditis. However, the capability of this method to distinguish between patients with the working diagnosis of MINOCA is yet to be tested.
We aimed to compare standard CMR parameters and investigate the differential diagnostic value of CMR-FT myocardial strain in pts with the working diagnosis of MINOCA.
From our consecutive register of pts with troponin positive acute coronary syndrome (n=234 pts) we enrolled 100 pts (47.7±14 y; 51 male) in this study.Twenty-five pts were selected randomly from each group of acute myocardial infarction (MI), acute myocarditis, Tako-Tsubo cardiomyopathy (TTC) and pts without structural alteration on CMR, and an additional group of healthy control (n=20, 46±8.2 y; 12 male). Standard CMR parameters such as left ventricular ejection fraction (LVEF), end-diastolic (LVEDVi) and end-systolic (LVESVi) volumes, myocardial mass were assessed and compared between the groups. We performed CMR-FT analysis of the left ventricle, including: global longitudinal (GLS), circumferential (GCS), standard deviation (SD) of the peak circumferential (CS) strain furthermore mechanical dispersion (MD), defined as the SD of the time-to-peak circumferential (MDC) strain of the LV segments expressed as percent of the cardiac cycle.
LVEF was lower (44±9.1%) and LVESVi (52.5±12.9ml/m2) was higher in TTC pts compared to all other groups (p<0.001). The LVEF, LVEDVi and LVESVi parameters did not show significant difference between MI and myocarditis pts (LVEF 56.5±7% vs 55±6.6%; LVEDVi 85.4±14.8 vs 92.7±10.7ml/m2; LVESVi 37.7±11.4 vs 41.5±9.1ml/m2). GLS and GRS were significantly reduced in TTC pts (−11.4±4.8%; 43.09±12.5%) compared to all other groups (p<0.001). GCS was impaired in pts with TTC, acute myocarditis and MI compared to healthy controls (−14±3.7 vs −18.7±3.7 vs −19.1±3.8 vs −23.2±3.1%, p<0.001), however there was no significant difference between myocarditis and MI pts. SD of the peak CS was lower in myocarditis compared to other groups (p<0.001). MDC was elevated in TTC and MI compared to myocarditis and healthy controls (16.3±5 vs 13.3±3.4 vs 8.1±3.3 vs 9.46±3.5% p<0.05). There was no significant difference between healthy controls and patients without structural alterations in any strain parameter.
Strain analysis of a TTC patient
Feature tracking analysis may enable differentiation between patients with MINOCA. TTC reduces global myocardial strain of the left ventricle and causes regional heterogeneity of the left ventricular contraction. Although standard volumetric CMR parameters and CMR based global strain values have limited capability to distinguish between MI and myocarditis with preserved ejection fraction, regional heterogeneity, expressible in MDC is significantly elevated in MI compared to myocarditis and healthy controls.

Acknowledgement/Funding
Project no. NVKP_16-1-2016-0017 has been implemented with the support provided from the National Research, Development and Innovation Fund of Hungary