ABC | Volume 115, Nº2, August 2020

Original Article Viana et al. ACS prognosis based on models and outcomes Arq Bras Cardiol. 2020; 115(2):219-225 with this type of outcome (C-statistic = 0,50; 95% CI 0,40 – 0,61) —p=0,027—Figure 1B. When the scores were divided into risk terciles, SYNTAX showed an increase in outcomes in the upper two terciles (8,4%, 22% and 22%, respectively, p = 0,007). However, GRACE showed no variation (9,6%, 9,3% and 13%, respectively, p = 0,57) — Figure 2, panels C e D. Clinical Characteristics versus Type of outcome Patients who evolved to death showed a tendency to higher risk clinical characteristics, compared to survivors. There was a significant difference between the two groups regarding creatinine (3,24 ± 2,6 and 1,15 ± 0,6; p < 0,001), acute left ventricular failure signs (58% and 12%, p < 0,001) and positive troponin (100% and 72%, p = 0,007), with a trend in age difference, ischemic electrocardiogram and blood pressure — Table 2. Nevertheless, there wasn’t any difference of those characteristics between patients who evolved with a non-fatal event versus event-free patients — Table 3. When evaluating the death event, most of those who showed this outcome already had a tri-arterial obstructive disease and/or left main coronary involvement (81%). In the survivors, only 25% had tri-arterial or left main coronary disease, followed by 22% with obstruction of two vessels, 29% with obstruction of one vessel and 24% free of obstructive injury (P ≤ 0,01). On those who showed non-fatal outcomes, the proportion of non-obstructive coronaropathy, one vessel obstruction, two vessels obstruction, tri-arterial/left main coronary were 7,7%, 23%, 26% e 44%, respectively, comparing to 25%, 29%, 21% and 25%, respectively, in free- event individuals (P=0,04) Discussion The present study requested a further refinement in risk prediction in patients with acute coronary syndrome (ACS). It was demonstrated how well the clinical paradigm (GRACE) as anatomical (SYTNAX) showed good capacity attributed to death, however only the anatomical model was able to predict recurrent non-fatal events. This demonstration that the scores commonly used in the clinical laboratory of patients with ACS may use a predilection for different outcomes, so far, have not been used in the literature. It is known that anatomical extension of coronary disease is an independent predictor of plaque progression and recurrent coronary events. 12 When evaluating the same angiographic predictor model used in this cohort, a previous study with optical coherence tomography demonstrated a higher frequency of characteristics compatible with vulnerability of plaque (plaque rich in lipid content, thin-cap fibroatheroma, rupture of plaque in the culprit lesion and multiple broken plaques in the culprit vessel) in patients with ACS with a higher SYNTAX score (≥16) than in tertiles of the low score (<9) and intermediate (between 9 and 16). 13 Another study carried out in patients with ACS demonstrated that the SYNTAX score is an independent predictor of infarction recurrence, with the best SYNTAX value of 11 to predict this outcome in this population. 14 In addition, the same group demonstrated that the higher the value of SYNTAX after percutaneous intervention, which was called Residual SYNTAX, there was an association with a higher occurrence of fatal and non-fatal outcomes in 30 days and 1 year, with predictive values ​and discriminatory accuracy similar to the baseline SYNTAX score (pre-treatment). 15 Our study demonstrated that the SYNTAX score is a reasonable predictor of recurrent non-fatal events, in line with the evidence that associates the burden of atherosclerotic disease with this type of outcome. The GRACE score is a model extensively studied in the prediction of major cardiovascular events in different ACS scenarios. 16-18 Despite this, there is a paucity of data in the literature that assess the predictive accuracy of this score for non-fatal outcomes in isolation. Most studies are associated with combined event prediction (MACE). The clinical variables present in this model reflect the patient’s degree of vulnerability to the insult presented in an ACS and, despite predicting anatomical complexity, it does not have a good predictive accuracy, according to data previously demonstrated by our group. 19-21 The current study has not been able to demonstrate an association between the GRACE score and the occurrence of new non-fatal ischemic events. From a mechanistic point of view, the difference between the findings of these scores can be interpreted through the characteristics of the variables that each one analyzes. The GRACE score uses in its composition variables related to the clinical aspect of the patient and, in a way, is associated with the potential risk of instability in a wide range of patients. However, it is not directly correlated with coronary instability, since due to its composition it is not possible to properly identify the severity of existing lesions. On the other hand, the SYNTAX score, used as the anatomical paradigm, is Table 1 - Clinical Characteristics and sample outcomes Clinical Characteristics Sample Size 365 Age (years) 64 ± 14 Male 210 (58%) Ischemia signs in electrocardiogram 166 (46%) Clinical presentation Unstable Angina 98 (27%) Non-ST-elevation myocardial infarction 196 (54%) ST-elevation myocardial infarction 71 (19%) Positive troponin 232 (64%) Tri-arterial or left main coronary 131 (36%) Serum creatine (mg/dl) 1,0 ± 0,7 Ejection fraction < 45% 45 (13%) Killip class > 1 51 (14%) GRACE Score* 117 (90 – 140) SYNTAX Score* 9 (2,5 – 20) Cardiovascular death 16 (4,4%) Non-fatal recurrent events 39 (11%) NSTEMI Non-ST-elevation myocardial infarction; STEMI: ST-elevation myocardial infarction; *: variable exposed as median and interquartile range. 221