P6418Modified shock index - an independent predictor of acute heart failure and in-hospital mortality in patients with ST-segment elevation myocardial infarction

Abstract

Introduction: Acute heart failure (AHF) and cardiogenic shock (CS) remain a dreadful complication of ST-segment elevation myocardial infarction (STEMI). In these patients, a modified shock index (MSI) ≥1.3 has been associated with higher mortality rates and AHF. Our study aims to assess the predictive value of MSI ≥1.3 for AHF, in-hospital mortality and 1-year mortality and hospitalization rate in patients admitted with STEMI. Methods: The authors present a retrospective, descriptive and correlational study with all patients admitted with a STEMI in a Cardiology department between the 1st of October 2010 and 31st of August 2015. The baseline characteristics and hospitalization data of patients with MSI (mean arterial pressure / heart rate) ≥1.3 were compared to patients with a MSI <1.3. The 1-year follow-up was made through phone call by a Cardiologist. We performed a univariate and multivariate statistical analysis of in-hospital mortality, as well as mortality and hospitalization rate at 1 year, using SPSS. Results: A total of 1478 patients were included, 1138 (77%) of which were men, with a mean age of 63,93±13,39 years. A MSI ≥1.3 was present in 96 (6.5%) patients and was more common in females (10,9% vs 5,2%, p<0,01) and older patients (65,6 vs 63,8 years, p=0,2). It was also associated with diabetes mellitus, past history of stroke and dementia. On admission, patients with a MSI ≥1.3 had more frequently an anterior MI (71,9% vs 41,1%, p<0,001), atrial fibrillation (17,7% vs 4,1%, p<0,01), a Killip Class ≥2 (49% vs 8,3%, p<0,001) or CS (29,2% vs 1,7%, p<0,01) and lower hemoglobin levels (13,3 vs 14,1, p<0,001). This group of patients also had lower left ventricular ejection fraction (43,95% vs 56,46%, p<0,001), more malignant arrhythmias (6,3% vs 1,6%, p<0,01), and had less coronary catheterization (74% vs 87,4%, p<0,001) and percutaneous coronary intervention (67,7% vs 82,2%, p<0,001). They had more frequently left main occlusion (3,1% vs 0,5%, p=0,002). There was no relation between a MSI ≥1.3 and other coronary artery disease. These patients were more frequently treated with invasive mechanical ventilation (14,6% vs 3,0%, p<0,001) and noninvasive ventilation (6,3% vs 0,7%, p<0,001). Regarding outcomes, a MSI ≥1.3 was strongly associated with in-hospital mortality (28,1% vs 4,3%, p<0,001) but not 1-year mortality (12,8% vs 7,1%, p=0,15) or hospitalization rate (27,7% vs 17,2%, p=0,07). On multivariate statistical analysis, a MSI ≥1.3 was a strong independent predictor of AHF at admission or during hospitalization (OR 3.66, 95% CI 1.7-8.1, p=0,001) and in-hospital mortality (OR 4.48, 95% CI 1.8-11.1, p=0,001). Conclusion: In our study, a MSI ≥1.3 was a strong independent predictor of AHF and in-hospital mortality among STEMI patients, although it was not associated with 1-year outcomes. This is an easily accessible tool that can help identify more critical patients and monitor them more closely during hospitalization.