Establishment and Validation of an Extracellular Volume Model Without Blood Sampling in STEMI Patients

Abstract

Abstract Aims Recent studies have shown that extracellular volume (ECV) can also be obtained without blood sampling by the linear relationship between hematocrit (HCT) and blood pool R1 (1/T1). However, whether this relationship holds for patients with myocardial infarction is still unclear. This study established and validated an ECV model without blood sampling in ST-segment elevation myocardial infarction (STEMI) patients. Methods and results A total of 398 STEMI patients who underwent cardiac magnetic resonance (CMR) examination with T1 mapping and venous HCT within 24 hours were retrospectively analyzed. All patients were randomly divided into a derivation group and a validation group. The mean CMR scan time was three days after primary percutaneous coronary intervention (pPCI). In the derivation group, a synthetic HCT formula was obtained by the linear regression between HCT and blood pool R1 (R^2=0.45, p<0.001). The formula was used in the validation group; the results showed high concordance and correlation between synthetic ECV and conventional ECV in integral (Bias=-0.12; R^2=0.92, p<0.001), myocardial infarction site (Bias=-0.23; R^2=0.93, p<0.001) and non-myocardial infarction sites (Bias=-0.09; R^2=0.94, p<0.001). Conclusion In STEMI patients, synthetic ECV without blood sampling had good consistency and correlation with conventional ECV. This study might provide a convenient and accurate method to obtain the ECV from CMR to identify myocardial fibrosis.