Value of the „Grey Zone“ as predictor for survival and ejection fraction in patients after acute myocardial infarction

Clara Staats (Bad Krozingen)1, R. Schmitt (Bad Krozingen)1, J. Brado (Bad Krozingen)1, K. Kaier (Freiburg im Breisgau)2, J. Hein (Bad Krozingen)1, M. Apweiler (Bad Krozingen)1, M. Hein (Bad Krozingen)1, D. Westermann (Bad Krozingen)1, P. Breitbart (Bad Krozingen)1, P. Ruile (Bad Krozingen)1

1Universitäts-Herzzentrum Freiburg / Bad Krozingen Klinik für Kardiologie und Angiologie Bad Krozingen, Deutschland; 2Institut für Medizinische Biometrie und Statistik Freiburg im Breisgau, Deutschland


Background: The greyzone fibrosis (GZF), consisting of myocardial fibrosis and viable myocardium, has been described as a risk factor for arrhythmias after myocardial infarction (MI) and can be detected via cardiac magnetic resonance (CMR). Yet, data about the correlation between the amount of GZF and long-term clinical parameters are scarce. The purpose of this study was to quantify GZF and to evaluate its predictive capabilities for two-year MI-free survival and one-year improvements in ejection fraction.


Methods Candidates for participation in the study were all patients who had suffered a myocardial infarction between september 2014 and november 2019 and subsequently received an CMR before discharge and a second CMR on average after 6 months. Image analysis was performed with a dedicated post-processing workstation (cvi42, Circle Cardiovascular Imaging Inc., Bellevue WA, USA). Late gadolinium enhancement (LGE) was quantified in both, grey zone only in the follow-up CMR after resolution of the initial infarct edema. Left-ventricular ejection fraction (LVEF) was measured in both CMR. High-sensitivity cardiac troponin T (hs-cTnT) levels were measured at admission as well as 8, 16 and 24 hours after percutaneous coronary intervention (PCI). Follow-up telephone visits were conducted annually for up to 8 years. 

For two year MI-free survival, univariable cox regression models were conducted and Harrels’s C and Royston and Sauerbrei's D were calculated as discrimination measures and compared across different potential predictors. For one-year improvements in ejection fraction, linear regression models were conducted and the coefficients of determination R2 were calculated and compared.


Results: 176 patients (18.2% female, 63.3 + 11.4 years) with acute myocardial infarction (114 with ST-segment elevation myocardial infarction, 62 with non-ST-segment elevation myocardial infarction) were included in this study. During the follow-up period of 1308 + 320 days 6 patients died (3.4%) and 7 patients suffered a second myocardial infarction (4.0%).

LGE measurements were associated with better predictive capabilities regarding 

MI-free survival (Harrell’s C of 0.714 and 0.708 of LGE volume and LGE mass, respectively) compared to GZF (0.590 and 0.571). hs-cTnT also performed better (Harrell’s C of 0.648) than GZF. As an univariable predictor for MI-free survival, only hs-cTnT reached significance (p<0.05). 

With regard to one-year improvements in ejection fraction, hs-cTnT and LGE measurements were acceptable predictors for an improvement in ejection fraction (p<0.05), but GZF measurements were not suitable as predictors (p>0.5). 


Conclusions: The GFZ, examined in CMR, has a worse prediction compared to hs-cTnT and LGE for patients after acute MI regarding the endpoint MI-free survival. Furthermore, GZF is not suitable as a predictor of improvement of LVEF. Therefore, routine determination of the GFZ can be dispensed with.

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