Non-ST elevation myocardial infarction? Intervene!

Abstract

The GRACE score, derived from the Global Registry of Acute Coronary Events, is an easily applicable and validated tool for triage decision making in patients after non-ST elevation myocardial infarction (NSTEMI) [1, 2]. In short, if patients with NSTEMI are admitted with a low GRACE score, a less aggressive diagnostic approach can be followed than in patients with a high GRACE score. The presence of NSTEMI suggests non-transmural necrosis, which therefore did not lead to end-stage infarction. NSTEMI should be considered alarming since so much can be gained from prevention of further transmural infarction. In this respect, only 28% of the patients with NSTEMI admitted in the GRACE study received a percutaneous coronary intervention (PCI) and 10% received coronary artery bypass grafting (CABG). PCI was performed with a mean delay of 83 h in NSTEMI patients and 62 h in STEMI patients. Five percent of patients with NSTEMI received thrombolysis. This means that 57% of patients with NSTEMI received no treatment leading to any form of revascularization and 62% received no PCI or CABG, preventing further myocardial damage [3]. Those patients who were treated with some form of intervention were treated relatively late compared with those treated according to the modern standard. It is therefore very likely that analysing data from patients who were treated according to today’s management of NSTEMI will show better results than those treated differently. This applies especially if surgery can be postponed for at least two days [4]. The GRACE study unfortunately lacks data on the outcome per subgroup with or without intervention and per CABG and PCI. Senanayake et al. [5] show, in this issue, that application of a modern approach to surgically treat NSTEMI leads to excellent results. However, this study does not provide data on the number, the method of treatment and the outcome of all NSTEMI patients admitted to the study hospital, since no data on PCI patients and medically treated patients are available. In the study population that needed surgery, 90% of patients were identified as having three-vessel disease and 50% had left main stenosis. Therefore, many cases of NSTEMI did not reach the criteria for surgery. More importantly, those who did receive CABG may have benefitted the most from surgical intervention. It is possible, if not likely, that a larger percentage of patients were treated with PCI or CABG than those in the GRACE study. A comparison, in 2005, between risk scores in which 65.9% of patients with NSTEMI received either PCI or CABG showed that the GRACE score was the best risk score available [2]. In contrast, a recently published study showed that between 2005 and 2007 still only 40% of patients undergoing angiography for NSTEMI received PCI and 10% were treated with surgery [9]. The differences between the patients included in the GRACE study, described here and in the current study, can explain the extreme difference between the observed and expected mortality for the GRACE risk groups. This study suggests that the mere value of the GRACE score as an absolute risk percentage is influenced by the choice of treatment (medically, PCI or CABG). The study shows that the GRACE score is not reliable as an estimation of the absolute risk for patients with an indication for surgery. Then what does the GRACE score tell us? The presence of NSTEMI in general means that some form of revascularization may be indicated. We should not see the GRACE score as a predictive score for mortality in coronary surgery, but merely as a tool for diagnostic triage and then use other tools (i.e. guidelines [6 ]o r the results from SYNTAX [7, 8]) to make the decision on therapy. If the GRACE score is used for decision making towards performing any kind of treatment this study stresses that this use is inappropriate. This study does show that surgery can be performed safely, especially in the middle GRACE score group. In summary, NSTEMI means that the patient could be at risk. The GRACE score can be of help in identifying which patients are particularly at risk and are in need of diagnosis (subsequently leading to treatment, preferably intervention). In NSTEMI patients with an indication for CABG, surgery can be performed safely. The use of the GRACE score for triage in the work-up reduces the risk.