Shock index and modified shock index at discharge as predictors of long-term mortality after myocardial infarction: results from the Augsburg Myocardial Infarction Registry.

BACKGROUND

Shock index (SI) and modified shock index (mSI), measured at hospital admission, have been shown to be predictive for mid- and long-term outcomes after acute myocardial infarction (AMI). Whether these associations also hold when indices are measured at discharge is unclear, so this study's aim was to analyze the association between SI and mSI at discharge and long-term mortality after AMI.

MATERIAL AND

METHODS

This analysis included 11,676 AMI cases registered by the population-based Myocardial Infarction Registry Augsburg. The follow-up time was restricted to a maximum of 5 years. Patients were categorized into low and high SI or mSI groups through separation at 75th percentiles for STEMI and NSTEMI, respectively. Analysis of survival included Kaplan-Meier curves with log-rank tests and multivariable-adjusted Cox-regression models.

RESULTS

Cut-off values were 0.6667 (STEMI) and 0.6545 (NSTEMI) for SI and 0.9231 (STEMI) and 0.9120 (NSTEMI) for mSI. Kaplan-Meier analysis showed significantly higher mortality for high SI and mSI groups in STEMI and NSTEMI patients. In STEMI cases, multivariable-adjusted Cox-regression analyses revealed significantly higher mortality for the high SI group (hazard ratio (HR): 1.25 (1.02-1.53), p value: 0.030), while mSI was non-significantly associated with long-term mortality (HR: 1.21 (0.99-1.48), p value: 0.060). Neither SI nor mSI was independently associated with mortality in NSTEMI.

CONCLUSION

SI and mSI at discharge represent valuable tools for long-term post-infarction risk stratification especially in STEMI cases and can support decision-making regarding individualized ambulatory care.