The present study is, to the best of our knowledge, the first report on the relationship between SS and myocardial injury in STEMI patients presenting to hospital within 24h from symptom onset. We identified three major findings:(1) there was a significant positive correlation between SS and IS and negative correlation between SS and MSI (Fig. 3). (2) compared with LSS group, MHSS group has lower LVEF deprived by CMR and higher LVESV, but LVEDV was comparable between groups. (3) according to the univariate and multivariate logistic models, SS (both as categorical variable and continuous variable) was the independent predictor of high IS after adjusted for confounders (Fig. 6).
In the CvLPRIT study[14], patients treated with a staged complete revascularization (CR) had higher SS
(18.3, 15–26 vs. 16, 12–21.5, p = 0.021) than those treated with immediate CR. Interestingly, staged approach patients also had larger IS (%LV) (19.1,10.2–37.1 vs. 11.6 ,6.8–17.6, p = 0.006) and lower MSI (35.1,5.9–66.4 vs.61.7,37.4–75.5, p = 0.008) compared with immediate CR. However, there was no direct relationship among them were stated. In another several studies[10, 11, 15, 16], in patients undergone CABG or PCI, SS was not only positively related to peri-procedural myocardial injury (deprived by elevated cardiac troponin and CKMB 6h after operation), but also an independent predictor of it. The increase in release of cardiac biomarkers after selective PCI was significantly associated with the extent of atherosclerosis identified by the SS [17]. These findings were consistent with those of our study. Furthermore, in our study, there was no significant relationship between SS and AAR was detected, thus, the negative correlation between SS and MSI might be interpreted by the positive correlation between SS and IS.
In our study, the LVEF-TTE in LSS group was comparable with that in MHSS group (57.63 ± 8.87 VS
54.77 ± 9.55, p = 0.070), however, LVEF-CMR in LSS group was significantly higher than that in MHSS group (52.86 ± 13.45 VS 45.65 ± 12.01, p = 0.001). In our study population, LVEF-CMR was lower than LVEF-TTE, in parallel to another recent multicenter registry[18]. Compared with LVEF-TTE, LVEF-CMR significantly improved MACE prediction in the group of patients with echocardiography-LVEF < 50%, and had better prognostic meaning[18].
The influence of SS on myocardial injury after STEMI could have important clinical implication. In China,
CMR was available in only few of large hospitals. Risk stratification for STEMI patients is very important. By evaluating the SS, we might find the patients who have high risk of myocardial injury. Despite numerous failures to date, the prevention and treatments for STEMI patients with high risk of myocardial injury should remain a focus of future cardiovascular research.
This study has a few limitations. First, the proportion of patients with specific SS group (< 22, n = 96;
22≤&<32, n = 36;>32, n = 17) in our population was too small to allow conclusions in all 3 groups. Consequently, tests of interaction were underpowered, especially when adjusted for covariates. Therefore, bias from residual confounding factors could still be present. Second, although all patients were enrolled consecutively, part of them declined CMR for personal reasons or unstable clinical station, for example, severe heart failure; on the other hand, only patients presented to hospital within 24h from symptom onset were included in our study population, thus it should be very cautious to interpretate the conclusions in the specific patients.
In conclusion, of STEMI patients within 24h from symptom onset, SS was positively related with IS and negatively with MSI. SS was an independent predictor of IS after adjusting for important covariates.