IJCS | Volume 31, Nº3, May/ June 2018

220 Cardoso et al. Correlation between coronary lesions and troponin International Journal of Cardiovascular Sciences. 2018;31(3)218-225 Original Article and graphics. Quantitative variables were expressed as median and interquartile range, and categorical variables as relative and absolute frequency. Statistical analyses were performed using the SPSS software version 24.0, and statistical significance was set at 5%. 12 Limitations - Small number of patients; - Some of the medical records data were missing, which made the exact calculation of the GRACE and TIMI prognostic score impossible; data of family history were also missing in 35.6% of the medical records. Most medical records did not contain patients’ body weight or time of symptom onset, which were required for TIMI calculation in patients with ST-segment elevation myocardial infarction (STEMI). No patient was rated because of missing body weight, since, from our experience, for most patients, body weight must have been greater than 67 kg. However, all patients were rated for ‘time of symptom onset’, since due to a failure in the city’s control system, most patients have been suffering pain for more than 4 hours when admitted to the service. For this reason, some patients may have received a score higher than they actually had, since some characteristics may have not been properly rated. - Patients with previous myocardial revascularization were not included in the analysis using the SYNTAX score, since this instrument does not consider the history of bypass. - Lack of standardization in the time of blood collection for troponin measurement, as well as lack of some measurements due to structural and operational problems of the service. This limitation may have influenced the detection of the peak concentration of this biomarker. Results Patients’ age varied from 37 to 92 years, and most patients were women, hypertensive, non-diabetic and non-smokers. Only 20.7% (n = 36) of patients had a positive history of CAD. Forty percent of the patients used acetylsalicylic acid (ASA) at themoment of the event, and most of them reported episodes of severe angina, without ST-segment depression in electrocardiography. Electrocardiographic changes other than ST-segment elevation or depressionwere not considered for analyses. Of the 174 patients evaluated, 19.0% (n = 33) had the diagnosis of STEMI, 43.1% (n = 75) had non ST-segment elevation myocardial infarction (non-STEMI), and 36.8% (n = 64) had unstable angina. Most patients were in Killip class I at admission. These results and the distribution of patients by history of diseases and Killip classification are described in Table 1. Results of quantitative clinical variables (vital data, biochemical and risk parameters) are described in Table 2. Median hsTn was 67 pg/mL. There was a significant moderate, positive linear correlation between hsTn levels and SYNTAX score (p < 0.001, r = 0.440) (Figure 1). In addition, a significant but weak positive linear correlation was found of hsTn levels with TIMI score (p < 0.001, r = 0.267), and GRACE score (p = 0.001, r = 0.261) (Figures 2 and 3, respectively). Discussion The relationship between altered hsTn and the prognosis of ACS patients has been consistently demonstrated in previous studies. However, few studies have correlated hsTn levels with the complexity of coronary lesions in patients undergoing coronary angiography. 9 Similarly, few studies comparing troponin levels with well-established clinical prognostic scores, such as TIMI and GRACE, have been found in the literature. Our results indicate that there is a significant, positive moderate linear correlation of hsTn levels with the complexity of coronary lesions evaluated by the SYNTAX scoring system. These findings may be explained by the fact that zero point has been assigned to many patients (n = 65/174), and many patients have not been rated because of the history of myocardial revascularization in SYNTAX score. In contrast, although patients with STEMI were the minority (33/174), they showed higher severity, and consequently higher hsTn levels (mean 3.073 pg/dL). However, we also included patients with unstable angina, who did not show increased hsTn levels, which may have caused a decrease in the mean value. For these reasons, despite positive, the importance of this correlation may be questioned. In the study by Altun et al., 9 involving 287 patients, a linear correlation of hsTn levels with the complexity of coronary lesions measured by the SYNTAX score was also reported, but with lower statistical power (r = 0.327) compared with our study (r = 0.440). The authors established a cut-off point for hsTn, above which the severity of coronary lesions was higher (high SYNTAX scores). This is a relevant conclusion, considering the