Defining high-risk patients with ST-segment elevation acute myocardial infarction undergoing primary percutaneous coronary intervention: a comparison among different scoring systems and clinical definitions.

Background: Identification of high-risk patients with ST-segment elevation acute myocardial infarction (STEMI) is of the utmost importance for adequate patient stratification and evaluation of additive treatments. However, there is no consensus on the optimal definition of high-risk patients.

Methods: We therefore compared 5 scoring systems in the assessment of the risk of 30-day mortality in 3214 patients with STEMI treated with primary percutaneous coronary intervention (PCI).

Results: Clinical scores showed a large variability in risk stratifying patients. Identification of high-risk patients ranged from 15% (PAMI score ≥ 9) to 66% (McNamara definition). McNamara, Antoniucci and Brodie definitions had the best sensitivity (0.87-0.88 and 95% confidence intervals (CI) ranging from 0.82-0.93) while PAMI ≥ 9 had the best specificity (0.87 with 95% CI of 0.86-0.88), while its sensitivity was quite low (0.42). In a sample size simulation of a trial aimed at demonstrating a 33% difference in 30-day mortality between two hypothetical treatments, the number of STEMI patients needed to be screened varied from 4712 for the Brodie definition to 9038 for the PAMI ≥ 9 score.

Conclusions: There is a large variability in risk stratification, sensitivity, specificity and predictive values among different scoring systems. These considerations should be taken into account when designing randomised trials.