Risk Stratification for CS After AMI

August 28, 2017

Key Takeaways

  • This substudy of the IABP-SHOCK II trial sought to develop an easy-to-use, readily available risk prediction score for short-term mortality in patients with AMI-related CS undergoing PCI.
  • The observed 30-day mortality rates were 23.8% (low risk score), 49.2% (intermediate risk score), and 76.6% (high risk score).
  • The IABP-SHOCK II risk score, which is correlated with mortality in patients with infarct-related CS, may help stratify patient risk for short-term mortality and might facilitate clinical decision making.

Risk stratification in the acute cardiac setting is crucial for determining the appropriate therapy, particularly in patients with cardiogenic shock (CS).1,Mortality rates among patients with acute myocardial infarction complication (AMI) CS is high,2,3 reinforcing the need for an easy-to-use risk score for appropriate care. Only three risk scores evaluating short-term mortality for acute myocardial infarction (AMI) complicating cardiogenic shock (CS) exist.4,5

A study by Pöss et al aimed to develop a 30-day mortality risk prediction score in patients with AMICS.6 The prime goal of the study was to design a score that was easy to apply in the cath lab in AMICS patients undergoing percutaneous coronary intervention (PCI).

Researchers obtained patient data (n=480) from the largest randomized CS trials to date, the IABP-SHOCK II trial. This trial, which features a large homogenous patient population, compared AMICS patients receiving intra-aortic balloon (IABP) support or no IABP support. Results from the trial showed no significant benefit of IABP support in overall survival.7

The Youden index was used to create optimal discriminatory cutpoints for 30-day survival, thereby enhancing the predictive value when dichotomizing variables.8

Six variables were deemed statistically significant predictors for 30-day mortality and were included in the model. These variables were age, arterial blood lactate at admission, creatinine at admission, glucose at admission, stroke history, and Thrombolysis in Myocardial Infarction (TIMI) flow grade of <3 following PCI.

The risk categories were given the following numerical range: low (0-2), intermediate (3-4), and high (5-9). Using chi-square testing, the mortality rates for the low, medium, and high risk scores were 23.8%, 49.2%, and 76.6%, respectively. C-statistics showed good predictive value; an area under the curve of 0.74 was calculated for the risk score in respect to 30-day mortality.

Figure 1: CS Complicating AMI: IABP-SHOCK I Risk Scorea
CS Complicating AMI: IABP-SHOCK I Risk Scorea
aData from Pöss J, Köster J, Fuernau G, et al6

The IABP-SHOCK II risk score is an easy-to-apply risk score that can be calculated quickly due to its simple, dichotomized variables and may help determine patient-specific mortality risk. These variables are also readily available upon completion of the PCI, thereby increasing its practical and simple utility in the cath lab.

According to the authors, the IABP-SHOCK II risk score may be best utilized for patient selection in clinical trials of patients with AMICS. In an accompanying editorial, Pinto DS and Grandin EW write, “More granular risk stratification may help to identify the “sweet spot” for therapeutic intervention in AMI CS...Pöss et al. (6) have advanced care for patients with AMI complicated by CS. The score appears to provide reproducible qualitative risk stratification for early death among patients with AMI CS who are undergoing PCI and may help triage for future studies.”8

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References:

  1. Pöss J, Desch S, Thiele H. Shock management in acute myocardial infarction. EuroIntervention. 2014;10:T74–82.
  2. Thiele H, Zeymer U, Neumann FJ, et al. Intraaortic balloon support for myocardial infarction with cardiogenic shock. N Engl J Med. 2012;367(14):1287-1296.
  3. Harjola VP, Lassus J, Sionis A, et al. Clinical picture and risk prediction of short-term mortality in cardiogenic shock. Eur J Heart Fail. 2015;17(5):501-509.
  4. Klein LW1, Shaw RE, Krone RJ, et al. Mortality after emergent percutaneous coronary intervention in cardiogenic shock secondary to acute myocardial infarction and usefulness of a mortality prediction model. Am J Cardiol. 2005;96(1):35-41.
  5. Sleeper LA, Reynolds HR, White HD, et al. A severity scoring system for risk assessment of patients with cardiogenic shock: a report from the SHOCK Trial and Registry. Am Heart J. 2010;160(3):443-450.
  6. Pöss J, Köster J, Fuernau G, et al. Risk Stratification for Patients in Cardiogenic Shock After Acute Myocardial Infarction. J Am Coll Cardiol. 2017;69(15):1913-1920.
  7. Thiele H, Zeymer U, Neumann FJ, et al. Intra-aortic balloon counterpulsation in acute myocardial infarction complicated by cardiogenic shock (IABP-SHOCK II): final 12 month results of a randomised, open-label trial. Lancet. 2013;382(9905):1638-1645.
  8. Pinto DS, Grandin EW. Risk Prediction in AMI Shock: Goldilocks and the Search for “Just Right.” J Am Coll Cardiol. 2017;69(15):1921-1923.

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