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Published on: June 12, 2021
Shock Index as a predictor for In-hospital mortality in patients with non-ST-segment elevation myocardial infarction
Akihiro Kobayashi1, Naoki Misumida1, Daniel Luger1
1Department of Internal Medicine, Mount Sinai Beth Israel, New York, USA.
Insights
Elevated shock index (SI), a heart rate to systolic blood pressure ratio, predicts higher in-hospital mortality in patients with non-ST-segment elevation myocardial infarction (NSTEMI). This finding aids in risk stratification for NSTEMI patients.
Area of Science:
- Cardiology
- Critical Care Medicine
- Clinical Risk Stratification
Background:
- Shock index (SI) is a known predictor of mortality in ST-segment elevation myocardial infarction.
- The prognostic utility of SI in non-ST-segment elevation myocardial infarction (NSTEMI) remains less understood.
Purpose of the Study:
- To investigate the prognostic value of the shock index in patients diagnosed with NSTEMI.
- To determine if an elevated SI is associated with adverse outcomes such as cardiogenic shock and in-hospital mortality in NSTEMI patients.
Main Methods:
- Retrospective analysis of 481 NSTEMI patients undergoing coronary angiography.
- Calculation of SI (heart rate/systolic blood pressure) upon presentation.
- Comparison of baseline characteristics, angiographic data, cardiogenic shock rates, and in-hospital mortality between patients with SI >= 0.7 and SI < 0.7.
Main Results:
- 103 patients (21.4%) had an SI >= 0.7.
- Patients with SI >= 0.7 exhibited a lower left ventricular ejection fraction and a significantly higher total incidence of cardiogenic shock (7.8% vs. 2.1%, p=0.001).
- In-hospital mortality was significantly higher in the SI >= 0.7 group (4.9% vs. 0.5%, p=0.006).
Conclusions:
- An elevated shock index (SI >= 0.7) is associated with increased cardiogenic shock and higher in-hospital mortality in patients with NSTEMI.
- SI serves as a valuable, readily available tool for risk stratification in NSTEMI patients.
- Further research may explore therapeutic implications based on SI values in NSTEMI.
Background/Purpose:
Shock index (SI), a ratio of heart rate/systolic blood pressure, has been reported to predict increased mortality in patients with ST-segment elevation myocardial infarction. However, the prognostic value of SI has not been fully elucidated in patients with non-ST-segment elevation myocardial infarction (NSTEMI).
Methods/Materials:
We performed a retrospective analysis of 481 consecutive NSTEMI patients who underwent coronary angiography from January 2013 to June 2014. Systolic blood pressure and heart rate on presentation were recorded, and SI was calculated as heart rate/systolic blood pressure. Patients were divided into those with SI≧0.7 and those with SI<0.7. Baseline and angiographic characteristics were recorded. In addition, cardiogenic shock and in-hospital mortality were recorded and compared between the two groups.
Results:
Among 481 patients, 103 patients (21.4%) had SI≧0.7. No statistically significant difference was observed in baseline characteristics between the two groups. Patients with SI≧0.7 had a lower left ventricular ejection fraction than those with SI<0.7 (56 [35-60] % vs. 60 [45-64] %, p=0.035). Patients with SI≧0.7 had a higher rate of cardiogenic shock on admission (2.9% vs. 0.3%, p=0.032). Patients with SI≧0.7 had a higher, albeit statistically insignificant, incidence of cardiogenic shock after admission (5.0% vs. 1.9%, p=0.074). The total incidence of cardiogenic shock was higher in patients with SI≧0.7 (7.8% vs. 2.1%, p=0.001). Patients with SI≧0.7 had higher in-hospital mortality (4.9% vs. 0.5%, p=0.006) than those with SI<0.7.
Conclusion:
Elevated SI was associated with higher in-hospital mortality in patients with NSTEMI.
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