Abstract 10904: The Seattle Post Myocardial Infarction Model (SPIM): Prediction of Mortality after Acute Myocardial Infarction

Abstract

Background: Ischemic heart disease is a leading worldwide cause of death. The Seattle Post Myocardial Infarction Model (SPIM) was developed to predict survival six months to two years after an acute myocardial infarction.

Methods: 6,632 subjects from EPHESUS were used to derive the predictive model, while 5,477 subjects from OPTIMAAL were used to validate the model. After analysis of univariate predictors, Cox proportional hazards modeling was used to develop a multivariate risk score predictive of survival at six months, one year, and two years.

Results: The SPIM risk score integrated lab and vital parameters (age, pulse, systolic blood pressure, Killip class, hemoglobin, sodium, white blood cell count, creatinine), features associated with the acute myocardial infarction (reperfusion therapy), the number of cardiac evidence-based medicines at baseline (aspirin, statin, beta-blocker, ACEI/ARB, aldosterone blocker), the region of the hospitalization, and the number of risk factors (current smoker and history of diabetes mellitus, cardiovascular disease, or heart failure). Each evidence based medicine improved survival by 15%, while each cardiac risk factor decreased survival by 38%. The model was predictive of all-cause mortality after myocardial infarction, with an AUC of 0.75 at six months and 0.75 at two years in the derivation cohort and 0.77 and 0.78 for the same time points in the validation cohort. This compared to 6-month AUCs of 0.69 and 0.73 for the GRACE discharge score in our derivation and validation cohorts (p<.0001 for the difference between SPIM and GRACE). Model predicted versus Kaplan-Meier observed survival was excellent in the derivation cohort and remained so in the validation cohort: 84.9% versus 85.0% at two years. Correlation between predicted and observed survival was high (r²=0.973, p<.0001). The 10% of subjects with the highest predicted risk had approximately 25 times higher mortality at two years than the 10% of subjects with the lowest predicted risk.

Conclusion: The SPIM score was a powerful predictor of outcomes after myocardial infarction. Its highly accurate predictions should improve patient and physician understanding of survival and may prove a useful tool in post-infarct risk stratification.