Impact of cardiac magnetic resonance for defining the etiology of an acute non-ischemic troponin rise depending on the pre-test diagnostic suspicion
Authors: Cecconi A , Martinez-Vives P , Rojas-Gonzalez A , Vera Sainz A , Olivera MJ , Hernandez-Muniz S , Lopez Melgar B , De Rueda Panadero C , Montes Muniz A , Diego Nieto G , Benedicto Buendia A , Dominguez Arganda L , Caballero P , Alfonso F , Jimenez-Borreguero LJ 
Published: February 2022

Abstract

Funding Acknowledgements
Type of funding sources: None.

Introduction
Cardiac magnetic resonance (CMR) is determinant for defining the final diagnosis in patients with an acute troponin rise of non-ischemic etiology. However, depending on the pre-test diagnostic suspicion, the usefulness of CMR to improve the final diagnosis may vary. Alluvial diagrams are not commonly applied to medicine fields, however, these charts offer a unique opportunity to visualize the changes in diagnosis after a specific test.

Purpose
The aim of the study was to define in which patients CMR may be more efficient for defining the final diagnosis of an acute rise of troponin. To reach our objective we applied for the first time an alluvial diagram to a cohort of patients undergoing CMR after an acute rise of troponins.

Methods
All consecutive patients admitted during a 2-year-period in our tertiary hospital with an acute non-ischemic troponin rise who underwent CMR were retrospectively included in the study. In patients with a suspicion of myocardial infarction, ischemic etiology was previously ruled out with an invasive coronary angiogram with concomitant intravascular imaging when necessary.
Based on patients´ clinical characteristics, wall motion abnormalities, ECG findings and cardiac biomarkers pattern a pre-CMR preliminary diagnostic suspicion was made: suspicion of Takotsubo syndrome, suspicion of myocarditis, non-ST-elevation troponin rise without a specific diagnostic suspicion or ST-elevation troponin rise without a specific diagnostic suspicion. Based on CMR findings a final diagnosis was obtained. The changes between pre-CMR and post-CMR diagnosis were analyzed using an alluvial diagram.

Results
A total of 64 patients were included. Thirty patients (47%) underwent coronary angiography which ruled out obstructive lesions. Previous to CMR, a high suspicion of Takostubo syndrome and myocarditis was present in 25 (39%) and 14 (22%) patients, respectively. Despite invasive angiogram, 1 ST-elevation troponin rise and 20 non-ST elevation troponin rise underwent CMR without a specific diagnostic suspicion. The diagnostic changes after CMR are presented in Figure 1. Takotsubo syndrome was confirmed in the 96% of patients with a high suspicion of Takotsubo syndrome and myocarditis was confirmed in all the patients with a high suspicion of myocarditis. Among patients without a specific suspicion of disease a final diagnosis was reached in 71% of them. Specifically, Takotsubo syndrome, myocardial damage, myocarditis and myocardial infarction were diagnosed in 25%, 10%, 30% and 10% of the patients, respectively.

Conclusions
For the first time an alluvial diagram describes the impact of CMR for defining the etiology of an acute non-ischemic rise of troponin. Based on our results, CMR has a confirmatory role in patients with a high suspicion of Takotsubo syndrome and myocarditis, whilst CMR findings provide a final diagnosis in the 71% of patients without a previous specific etiologic suspicion. Abstract Figure.