BackgroundLeft ventricular ejection fraction (LVEF) is often used as an assessment indicator for left ventricular systolic function. As adverse events occur in some patients with preserved LVEF, other phenotypes based on LVEF may exist in the population with LVEF ≥50%, affecting the prognosis.
ObjectiveTo explore the critical LVEF and possible pathogenesis in acute ST-elevation myocardial infarction (STEMI) patients with supra-normal ejection fraction after primary PCI.
MethodsA total of 272 STEMI patients with initial LVEF ≥50% by transthoracic echocardiographic measurement after being treated with primary PCI were selected from Heart Center, Hebei General Hospital from November 2016 to June 2018. All patients were admitted to the cardiovascular care unit following primary PCI. Data were collected, including baseline characteristics (gender, smoking history, drinking history, family history of cardiovascular disease, angina in the past one month, diabetes history, hypertension history, stroke history, old myocardial infarction, age, body mass index, pulse rate, and mean arterial pressure) , time of onset of chest pain〔including time from symptom onset to first medical contact, time from symptom onset to first antiplatelet therapy, time from symptom onset to first anticoagulation, symptom onset to balloon time (SBT) , door-to-balloon (D-to-B) time〕, periprocedural data 〔pre-procedural TIMI flow grade, collateral circulation, treatment of non-infarct related artery (NIRA) , thrombus aspiration, IABP application, anticoagulant medication, pre-procedural use of β-blockers, renin-angiotensin-aldosterone system inhibitors (RAASi) , or statins, intra-procedural application of tirofiban and prourokinase, post-procedure TIMI flow grade〕, laboratory test results (leukocyte count, Neutrophil count, lymphocyte count, hemoglobin, hematocrit, platelet count, potassium ion, urea nitrogen, creatinine, random blood glucose, eGFR, total cholesterol, triacylglycerol, high-density lipoprotein, low-density lipoprotein, very low-density lipoprotein, non-high density lipoprotein, creatine kinase, creatine kinase isozyme) and transthoracic echocardiographic data. The correlation between LVEF and in-hospital death was analyzed. By ROC analysis, the optimal threshold of LVEF predicting in-hospital death was obtained, and patients with LVEF greater and less than the optimal threshold were compared in terms of clinical indictors.
ResultsThe area under the ROC curve of LVEF predicting in-hospital death was 0.846〔95%CI (0.628, 1.000) , P=0.018〕, and the optimal threshold was 67.5% with a sensitivity of 75.0% and a specificity of 95.1%. Compared with those with LVEF <67.5%, patients with LVEF > 67.5% had higher in-hospital mortality〔18.8% (3/16) vs 0.4% (1/256) 〕, with a statistical difference (P<0.05) . Moreover, they also showed a statistical difference in Kaplan-Meier survival curve (χ2=36.526, P<0.001) . Furthermore, patients with LVEF > 67.5% showed higher female ratio and rate of IABP application, lower mean pulse rate as well as lower rate of post-procedure TIMI grade 2-3 flow (P<0.05) . They also demonstrated lower mean left ventricular end-systolic diameter (P<0.001) .
ConclusionThere may be a subgroup in STEMI patients with preserved ejection fraction after primary PCI, who presented higher LVEF (supra-normal LVEF) and higher in-hospital mortality than those with normal LVEF. The optimal threshold of LVEF for predicting in-hospital death in these STEMI patients was 67.5%. Being female and coronary microcirculation disorder may contribute to the development of supra-normal ejection fraction.
