Modified shock index: A bedside clinical index for risk assessment of ST-segment elevation myocardial infarction at presentation

• DOI: 10.1016/j.repc.2017.07.018
• Publication Date: 2018-05-25T23:22:52Z
• Authors: Glória Abreu; Pedro Azevedo; Carlos Galvão Braga; Catarina Vieira; Miguel Álvares Pe...; Juliana Martins; Carina Arantes; Catarina Rodrigues; Alberto Salgado; Jorge Marques
• Keywords: Cohort Studies; Male; Heart Rate; Point-of-Care Testing; RC666-701; Diseases of the circulatory (Cardiovascular) system; Humans; ST Elevation Myocardial Infarction; Arterial Pressure; Female; Middle Aged; Risk Assessment; Retrospective Studies

Prompt identification of higher-risk patients presenting with ST-segment elevation myocardial infarction (STEMI) is crucial to pursue a more aggressive approach.We aimed to assess whether the modified shock index (MSI), the ratio of heart rate to mean arterial pressure, could predict six-month mortality among patients admitted with STEMI.A retrospective observational cohort study was performed in a single center including 1158 patients diagnosed with STEMI, without cardiogenic shock on admission, between July 2009 and December 2014. They were divided into two groups: group 1 - patients with MSI<0.93 (72%); group 2 - patients with MSI≥0.93 (28%). The primary endpoint was six-month all-cause mortality.MSI≥0.93 identified patients who were more likely to have signs of heart failure (p=0.002), anemia (p<0.001), renal insufficiency (p=0.014) and left ventricular systolic dysfunction (p=0.045). They more often required inotropic support (p<0.001), intra-aortic balloon pump (p<0.001) and mechanical ventilation (p<0.001). Regarding in-hospital adverse events, they had a higher prevalence of malignant arrhythmias (p=0.01) and mechanical complications (p=0.027). MSI≥0.93 was an independent predictor of overall six-month mortality (adjusted HR 2.00, 95% CI 1.20-3.34, p=0.008).MSI was shown to be a valuable bedside tool which can rapidly identify high-risk STEMI patients at presentation.