Association of stress hyperglycemia ratio and poor long-term prognosis in patients with myocardial infarction with non-obstructive coronary arteries

Relationship between stress hyperglycemia ratio and prognosis in patients with aneurysmal subarachnoid hemorrhage: a two-center retrospective study

Previous research have demonstrated that the stress hyperglycemia ratio (SHR) accurately reflects acute hyperglycemic states and correlates with adverse outcomes. This study aims to explore the relationship between SHR and the prognosis of patients with aneurysmal subarachnoid hemorrhage (aSAH). Patients with aSAH were categorized into four groups based on SHR tertiles. Functional outcomes were evaluated at 12 months using the modified Rankin Scale (mRS), with scores ranging from 0 to 2 indicating a good outcome and 3-6 indicating a poor outcome. The associations between SHR and functional outcomes were analyzed using logistic regression models and restricted cubic spline analysis. A total of 127 patients exhibited poor functional outcomes. Following comprehensive adjustments, those in the highest SHR tertile had a significantly increased risk of poor prognosis compared to those in the lowest tertile (odds ratio [OR], 4.12; 95% confidence interval [CI]: 1.87-9.06). Moreover, each unit increase in SHR was associated with a 7.51-fold increase in the risk of poor prognosis (OR, 7.51; 95% CI: 3.19-17.70). Further analysis using restricted cubic spline confirmed a linear correlation between SHR and poor prognosis (P for nonlinearity = 0.609). Similar patterns were observed across all studied subgroups. Elevated SHR significantly correlates with poor functional prognosis at one year in patients with aSAH, independent of their diabetes status.

The correlation of atherogenic index of plasma with non-obstructive CAD and unfavorable prognosis among patients diagnosed with MINOCA

BACKGROUND

The atherogenic index of plasma (AIP) is linked to lipid metabolism and has shown considerable prognostic value in cardiovascular disorders. However, its role in myocardial infarction with non-obstructive coronary arteries (MINOCA) has not been investigated. We assessed the relationship between AIP, the severity of coronary stenosis, and prognosis in MINOCA.

METHODS

We included consecutive patients who were diagnosed with MINOCA. AIP was calculated using the base 10 logarithm of the ratio between the levels of TG and HDL-C. The patients were divided into four groups based on their AIP quartiles: Q1 (AIP<-0.145), Q2 (AIP≥-0.145and≤0.049), Q3 (AIP>0.049and≤0.253), and Q4 (AIP>0.253). All patients underwent follow-up for MACE.

RESULTS

The final analysis included 421 patients, with 188 having normal coronaries (0 stenosis) and 233 exhibiting non-obstructive coronary artery disease (CAD) (<50 % stenosis). In the multivariate logistic analysis, highest AIP (Q4) group was significantly associated with increased risk of non-obstructive CAD in MINOCA (OR,1.994;95 % CI:1.075-3.698; P = 0.029). During the follow-up period, MACE occurred in 22.8 % of MINOCA patients. Q4 group exhibited a significantly higher rate of MACE (P = 0.021). Furthermore, when both AIP and coronary stenosis status were considered, the results revealed individuals in the Q4 group with non-obstructive CAD had the highest risk of MACE (log-rank P = 0.027). The adjusted Cox analysis indicated that the Q4 group was associated with a 2.052-fold increase in the HR of MACE.

CONCLUSION

AIP exhibits a notable association with the incidence of MACE in MINOCA patients and serves as a substantial marker for non-obstructive CAD in this patient group.

Relationship between stress hyperglycemia and worsening heart failure in patients with significant secondary mitral regurgitation

BACKGROUND AND AIMS

Secondary mitral regurgitation (sMR), a major valvular disease, is prevalent in patients with coronary artery disease (CAD), and is associated with higher incidence of heart failure (HF) and mortality when present in combination with abnormal glucose metabolism. We aimed to evaluate the relationship between stress hyperglycemia ratio (SHR) and worsening HF in CAD patients with significant (grade ≥2) sMR.

METHODS

We performed a multi-center observational study of 874 participants with significant sMR following percutaneous coronary intervention (PCI) in the Cardiorenal Improvement-II (CIN-II) cohort. Patients with glucose and glycated hemoglobin (HbA1c) data at admission were included in the analysis, and categorized according to the SHR, the ratio of mmol/L blood glucose to % HbA1c, as quartiles: Q1: <0.74; Q2: 0.74-0.91; Q3: 0.91-1.14; and Q4: ≥1.14. The primary clinical endpoint was worsening HF and the secondary endpoint was major adverse cardiac events (MACE).

RESULTS

Of the 874 participants (64.1 ± 10.8 years, 80% male), 174 showed worsening HF and 226 developed MACE during a median follow-up of 3.7 years (interquartile range: 1.8-6.2 years). Compared to participants in the lowest quartile (Q1) of SHR, the highest quartile group (Q4) was at significantly higher risks of worsening HF (adjusted hazard ratio, 2.44; 95% confidence interval, 1.51-3.94; p< 0.001), while this was not associated with increased risk of MACE (p>0.05) after adjustment for potential covariates. For worsening HF, the results obtained for the normal glucose regulation subgroup may be more meaningful than those for the diabetes mellitus (DM) and pre-DM groups (p-interaction<0.001). For MACE, the acute myocardial infarction (AMI) (Q4 vs. Q1; HR: 0.65, 95%CI: 0.26-1.59) and non-AMI (Q4 vs. Q1; HR: 2.20, 95%CI: 1.36-3.54) subgroups differed significantly on MACE (p-interaction = 0.006).

CONCLUSIONS

Increasing SHR is associated with a higher risk of worsening of HF in patients with significant sMR, especially in those with normoglycemia.

Long-Term Prognostic Impact of Stress Hyperglycemia in Non-Diabetic Patients Treated with Successful Primary Percutaneous Coronary Intervention

BACKGROUND

stress hyperglicemia (SH) is common in patients with ST-elevation myocardial infraction (STEMI). The aims of this study were to analyze the impact of SH on the incidence of all-cause mortality and major adverse cardiovascular events (MACE-cardiovascular death, nonfatal reinfarction, target vessel revascularization, and stroke) in STEMI patients without diabetes mellitus (DM) who have been treated successfully with primary PCI (pPCI).

METHOD

we analyzed 2362 STEMI patients treated with successful pPCI (post-procedural flow TIMI = 3) and without DM and cardiogenic shock at admission. Stress hyperglycemia was defined as plasma glucose level above 7.8 mmol/L at admission. The follow-up period was 8 years.

RESULTS

incidence of SH was 26.9%. Eight-year all-cause mortality and MACE rates were significantly higher in patients with SH, as compared to patients without SH (9.7% vs. 4.2%, p < 0.001, and 15.7% vs. 9.4%, p < 0.001). SH was an independent predictor of short- and long-term all-cause mortality (HR 2.19, 95%CI 1.16-4.18, and HR 1.99, 95%CI 1.03-3.85) and MACE (HR 1.49, 95%CI 1.03-2.03, and HR 1.35, 95%CI 1.03-1.89).

CONCLUSION

despite successful revascularization, SH at admission was an independent predictor of short-term and long-term (up to eight years) all-cause mortality and MACE, but its negative prognostic impact was stronger in short-term follow-up.

Increased stress hyperglycemia ratio at hospital admission in stroke patients are associated with increased in-hospital mortality and length of stay

OBJECTIVE

Recently, the stress hyperglycemia ratio (SHR) has been introduced as a metric to signify relative hyperglycemia. This study aimed to investigate the relationship between SHR and in-hospital mortality and length of stay occurring during hospitalization in stroke patients.

METHODS

The retrospective cohort study comprised a total of 4,018 patients diagnosed with acute stroke. The SHR is expressed by the formula: SHR = ABG (mmol/L) / [1.59 × HbA1c (%) - 2.59]. Outcomes included in-hospital mortality and length of stay. Multivariable logistic and linear regression analyses were conducted. Receiver operating characteristic (ROC) analysis was performed to distinguish between the variables, and the area under the ROC curve (AUC) was compared.

RESULTS

In this analysis, a total of 4,018 individuals participated, including 2,814 male patients, accounting for 70.0%. Overall, in-hospital mortality and length of stay tended to rise as SHR increased. A higher prevalence of in-hospital mortality was observed with each standard deviation (SD) increase of the SHR (odds ratio [OR]: 1.26, 95% confidence interval [CI]: 1.05-1.52). Moreover, after considering the confounders, a significant positive association between SHR levels and length of stay was observed (β = 0.70, 95% CI: 0.40-1.00). ROC analysis showed that among stroke patients, SHR (AUC = 0.693) was more effective than admission blood glucose (ABG) (AUC = 0.646) and glycosylated hemoglobin (HbA1c) (AUC = 0.523), which were more predictive of in-hospital mortality.

CONCLUSIONS

Elevated SHR levels are associated with increased in-hospital mortality and prolonged length of stay in stroke patients.

Prognostic factors of MINOCA and their possible mechanisms

Objective

Despite not showing substantial stenosis of coronary arteries, Myocardial Infarction with Non-Obstructive Coronary Arteries (MINOCA) presents with myocardial ischemia injury, thus having a grave prognosis and a high risk of long-term complications. This necessitates increased clinical attention and exploration of its root causes to prevent a similar crisis.

Methods

Research on MINOCA is limited, especially in terms of its clinical attributes, long-term outlook, risk stratification, and prognosis-linked cardiometabolic risk factors. This review aims to fill these gaps, providing an extensive overview of clinical trials and studies on MINOCA to separate the issue from the presence of non-obstructive coronary arteries in cardiac patients.

Results

It has been found that MINOCA patients still face a high risk of long-term adverse events. Due to social and physiological factors, the hospital mortality rate is higher among women, and they are also more susceptible to MINOCA. Cardiac metabolic risk factors, including disorder of glucose and lipid metabolism, as well as changes in serum CysC levels, have significant impacts on the occurrence and prognosis of MINOCA.

Conclusions

Further research is still needed to fully understand the complex biological mechanisms underlying the prognostic factors of MINOCA. A profound understanding of these factors could reveal potential targets for improving prognosis, thereby indicating new strategies for managing this cardiovascular condition.

Stress hyperglycemia ratio as a prognostic indicator for long-term adverse outcomes in heart failure with preserved ejection fraction

BACKGROUND

Recent studies highlighted that stress hyperglycemia ratio (SHR) is a potential predictor for future risk in heart failure (HF) patients. However, its implications specifically in HF with preserved ejection fraction (HFpEF) are not yet fully elucidated. We aimed to investigate the association between SHR and long-term clinical outcomes in HFpEF patients.

METHODS

HFpEF patients enrolled between 2015 and 2023, were followed (mean 41 months) for a composite outcome of all-cause, cardiovascular mortality, and HF rehospitalization. SHR was established as the ratio of acute-chronic glycemia from admission blood glucose and glycated hemoglobin. The optimal cut-off for SHR to predict outcomes based on event prediction was determined through ROC analysis, and the cutoff was identified at 0.99. The effect of SHR on adverse risk was examined through the Cox hazards and Kaplan-Meier survival methods. A Pearson correlation analysis was conducted to assess the relationship between SHR and the severity of HF, as indicated by N-terminal pro-brain natriuretic peptide (NT-proBNP) levels. Furthermore, the incremental prognostic value of SHR was further assessed by the integrated discrimination improvement (IDI) and the net reclassification improvement (NRI).

RESULTS

Among the 400 enrolled patients, 190 individuals (47.5%) encountered composite events over the 41-month follow-up period. SHR was significantly elevated in patients with events compared with those without (p < 0.001). All patients were stratified into high SHR (n = 124) and low SHR (n = 276) groups based on the SHR cutoff. The high SHR group had a significantly higher incidence of adverse events than the low SHR group (log-rank; p < 0.001). Additional analysis indicated a poorer prognosis in patients with low left ventricular EF (LVEF) levels (50 < LVEF < 60) and high SHR (SHR > 0.99) in comparison to the other groups (log-rank p < 0.001). In adjusted analysis, after accounting for age, sex, diabetes, and NT-proBNP, elevated SHR remained independently predictive of adverse outcomes (adjusted HR: 2.34, 95% CI 1.49-3.67; p < 0.001). Furthermore, adding SHR to a model with MAGGIC score provided an incremental improvement in predicting adverse events. Additionally, SHR displayed a slight correlation with NT-proBNP.

CONCLUSION

Elevated SHR was independently associated with an increased risk for composite events of all-cause, cardiovascular mortality, and HF readmission than those with lower SHR. SHR is a valuable tool for predicting and stratifying long-term adverse risks among HFpEF patients.

Association between fasting stress hyperglycemia ratio and contrast-induced acute kidney injury in coronary angiography patients: a cross-sectional study

Aims

Stress hyperglycemia ratio (SHR), an emerging indicator of critical illness, exhibits a significant association with adverse cardiovascular outcomes. The primary aim of this research endeavor is to evaluate the association between fasting SHR and contrast-induced acute kidney injury (CI-AKI).

Methods

This cross-sectional study comprised 3,137 patients who underwent coronary angiography (CAG) or percutaneous coronary intervention (PCI). The calculation of fasting SHR involved dividing the admission fasting blood glucose by the estimated mean glucose obtained from glycosylated hemoglobin. CI-AKI was assessed based on elevated serum creatinine (Scr) levels. To investigate the relationship between fasting SHR and the proportion of SCr elevation, piecewise linear regression analysis was conducted. Modified Poisson's regression analysis was implemented to evaluate the correlation between fasting SHR and CI-AKI. Subgroup analysis and sensitivity analysis were conducted to explore result stability.

Results

Among the total population, 482 (15.4%) patients experienced CI-AKI. Piecewise linear regression analysis revealed significant associations between the proportion of SCr elevation and fasting SHR on both sides (≤ 0.8 and > 0.8) [β = -12.651, 95% CI (-23.281 to -2.022), P = 0.020; β = 8.274, 95% CI (4.176 to 12.372), P < 0.001]. The Modified Poisson's regression analysis demonstrated a statistically significant correlation between both the lowest and highest levels of fasting SHR and an increased incidence of CI-AKI [(SHR < 0.7 vs. 0.7 ≤ SHR < 0.9) β = 1.828, 95% CI (1.345 to 2.486), P < 0.001; (SHR ≥ 1.3 vs. 0.7 ≤ SHR < 0.9) β = 2.896, 95% CI (2.087 to 4.019), P < 0.001], which was further validated through subgroup and sensitivity analyses.

Conclusion

In populations undergoing CAG or PCI, both lowest and highest levels of fasting SHR were significantly associated with an increased occurrence of CI-AKI.

Impact of stress hyperglycemia ratio, derived from glycated albumin or hemoglobin A1c, on mortality among ST-segment elevation myocardial infarction patients

BACKGROUND

Stress hyperglycemia ratio (SHR), associated with adverse outcomes in patients with ST-segment elevation myocardial infarction (STEMI), has several definitions. This study aims to assess the prognostic value of SHR, derived from hemoglobin A1c (HbA1c) or glycated albumin (GA), to mortality.

METHODS

The study comprised 1,643 STEMI patients who underwent percutaneous coronary intervention (PCI) in two centers. SHR1 was calculated using fasting blood glucose (FBG)/GA, while SHR2 was calculated using the formula FBG/(1.59*HbA1c-2.59). The primary endpoints were in-hospital death and all-cause mortality, with a median follow-up duration of 1.56 years.

RESULTS

Higher SHR1 and SHR2 values are associated with increased risks of in-hospital death and all-cause mortality. Each standard deviation increase in SHR1 corresponded to a 39% and 22% escalation in in-hospital death and all-cause mortality, respectively. The respective increases for SHR2 were 51% and 26%. Further examinations validated these relationships as linear. Additionally, the areas under the curve (AUC) for in-hospital death were not significantly different between SHR1 and SHR2 (p > 0.05). Incorporating SHR1 or SHR2 into the base model significantly improved the discrimination and risk reclassification for in-hospital and all-cause mortality. A subgroup analysis revealed that the effects of SHR1 and SHR2 were more pronounced in patients with hypercholesteremia.

CONCLUSION

SHR1 and SHR2 have emerged as robust and independent prognostic markers for STEMI patients undergoing PCI. The SHR calculation based on either HbA1c or GA can provide additional predictive value for mortality beyond traditional risk factors, helping to identify high-risk STEMI patients.

Prognostic value of stress hyperglycemia ratio in patients with acute myocardial infarction: A systematic review with Bayesian and frequentist meta-analysis

The present systematic review and meta-analysis aimed to investigate the prognostic value of stress hyperglycemia ratio (SHR) in patients with acute myocardial infarction (AMI). A total of 26 cohort studies, involving 87,974 patients, were analyzed. The frequentist meta-analysis showed that AMI patients with SHR in the upper quantile had a significantly higher hazard of major adverse cardiovascular and cerebrovascular events (MACCE, HR = 1.7; 95 % CI= [1.42, 2.03]; P < 0.001; I2 = 71 %; P <0.01), long-term (HR = 1.64; 95 % CI= [1.49, 1.8]; P < 0.001; I2 = 16 %; P = 0.29) and in-hospital all-cause mortality (OR = 3.87; 95 % CI= [2.98, 5.03]; P < 0.001; I2 = 54 %; P = 0.03) compared to those with lower SHR. Prespecified subgroup analyses revealed that these results were consistent irrespective of diabetes status (P = 0.32 and 0.73 for subgroup differences) and that SHR was a significant predictor of MACCE both in AMI with obstructive coronary arteries (HR = 1.57; 95 % CI= [1.34, 1.83]; P < 0.001; I2 = 66 %; P < 0.01) and MINOCA (HR = 2.57; 95 % CI= [1.86, 3.56]; P < 0.001; I2 = 0 %; P = 0.84). The Bayesian analyses with weakly prior assumptions yielded comparable results with the frequentist approach and provided strong evidence that higher SHR values were associated with significantly greater hazard of MACCE, short-term and long-term mortality. Further, prospective research is warranted to provide deeper insights into this newer index of stress hyperglycemia before its potential incorporation in clinical prediction scores.

MINOCA biomarkers: Non-atherosclerotic aspects

Myocardial infarction in the absence of obstructive coronary artery disease (MINOCA) is an important subtype of myocardial infarction. Although comprising less than 50% stenosis in the main epicardial coronary arteries, it constitutes a severe health risk. A variety of approaches have been recommended, but definitive diagnosis remains elusive. In addition, the lack of a comprehensive understanding of underlying pathophysiology makes clinical management difficult and unpredictable. This review highlights ongoing efforts to identify relevant biomarkers in MINOCA to improve diagnosis, individualize treatment and better predict outcomes.

MINOCA: A Working Diagnosis

Cases of patients presenting with myocardial infarction (MI) without angiographic obstructive CAD are not trivial and have significant prevalence. "The Fourth Universal Definition of MI" (4UDMI) published in 2018 introduced MI with non-obstructive coronary arteries (MINOCA). The new section was of great importance as it validated the diagnosis by defining its criteria and recognizing its presence in the community and the need for further investigation. Given the nature of the diagnosis of MINOCA, coronary angiography provides limited information about prognosis and risk stratification for future major adverse cardiovascular events (MACE). Thus, additional imaging to understand the underlying etiology of MINOCA in conjunction with a better understanding of prognostic factors is necessary to expand on the current guidelines and aid in screening for possible complications, risk of MACE, and all-cause mortality. Discerning the etiology of the presentation is crucial, and physiologic studies, as well as additional imaging, are an important part of this evaluation. These modalities include intravascular studies such as optical coherence tomography (OCT), intravascular ultrasound (IVUS), fractional flow reserve (FFR), and imaging in the form of cardiac CT (CCT) and cardiac MRI (CMR). This step is essential to target treatment regimens more efficiently. The purpose of promoting multiple imaging modalities beyond traditional angiography is to address the working MINOCA diagnosis, with the finality of identifying the specific ischemic pathophysiology. MINOCA has multiple causative mechanisms, making it a heterogeneous collection of etiologies, resulting in acute MI: atherosclerotic, and non-atherosclerotic. This literature revision demonstrates that MINOCA prevalence and mortality are not trivial, and the diagnosis affects quality of life. MINOCA presents a definitive risk of MACE without proper stratification and targeted medical therapy. Several prognostic factors of morbidity and mortality in MI-CAD patients have been identified to correlate with MINOCA patients, especially inflammatory markers. MINOCA is not an exclusion diagnosis but a working diagnosis for which further imaging studies should be performed.

Predictive value of the stress hyperglycemia ratio in dialysis patients with acute coronary syndrome: insights from a multi-center observational study

BACKGROUND

Various studies have indicated that stress hyperglycemia ratio (SHR) can reflect true acute hyperglycemic status and is associated with poor outcomes in patients with acute coronary syndrome (ACS). However, data on dialysis patients with ACS are limited. The Global Registry of Acute Coronary Events (GRACE) risk score is a well-validated risk prediction tool for ACS patients, yet it underestimates the risk of major events in patients receiving dialysis. This study aimed to evaluate the association between SHR and adverse cardiovascular events in dialysis patients with ACS and explore the potential incremental prognostic value of incorporating SHR into the GRACE risk score.

METHODS

This study enrolled 714 dialysis patients with ACS from January 2015 to June 2021 at 30 tertiary medical centers in China. Patients were stratified into three groups based on the tertiles of SHR. The primary outcome was major adverse cardiovascular events (MACE), and the secondary outcomes were all-cause mortality and cardiovascular mortality.

RESULTS

After a median follow-up of 20.9 months, 345 (48.3%) MACE and 280 (39.2%) all-cause mortality occurred, comprising 205 cases of cardiovascular death. When the highest SHR tertile was compared to the second SHR tertile, a significantly increased risk of MACE (adjusted hazard ratio, 1.92; 95% CI, 1.48-2.49), all-cause mortality (adjusted hazard ratio, 2.19; 95% CI, 1.64-2.93), and cardiovascular mortality (adjusted hazard ratio, 2.70; 95% CI, 1.90-3.83) was identified in the multivariable Cox regression model. A similar association was observed in both diabetic and nondiabetic patients. Further restricted cubic spline analysis identified a J-shaped association between the SHR and primary and secondary outcomes, with hazard ratios for MACE and mortality significantly increasing when SHR was > 1.08. Furthermore, adding SHR to the GRACE score led to a significant improvement in its predictive accuracy for MACE and mortality, as measured by the C-statistic, net reclassification improvement, and integrated discrimination improvement, especially for those with diabetes.

CONCLUSIONS

In dialysis patients with ACS, SHR was independently associated with increased risks of MACE and mortality. Furthermore, SHR may aid in improving the predictive efficiency of the GRACE score, especially for those with diabetes. These results indicated that SHR might be a valuable tool for risk stratification and management of dialysis patients with ACS.

High triglyceride-glucose index and stress hyperglycemia ratio as predictors of adverse cardiac events in patients with coronary chronic total occlusion: a large-scale prospective cohort study

BACKGROUND

The triglyceride-glucose (TyG) index and the stress hyperglycaemia ratio (SHR) are both positively associated with cardiovascular (CV) risk in patients with coronary heart disease. However, the prognostic value of these two biomarkers has not been well elucidated in patients with chronic total occlusion (CTO). Therefore, this study aims to evaluate the association of the TyG index and the SHR with long-term prognosis in patients with CTO.

METHODS

This prospective cohort study consecutively included 2740 angina patients with CTO from January 2017 to December 2018 at Fuwai Hospital. The outcomes are a composite of CV death and target vessel myocardial infarction (TVMI) and major CV cerebrovascular adverse events (MACCEs, including all-cause death, nonfatal MI, ischaemia-driven target vessel revascularization, and stroke). The association between biomarkers and prognosis was analysed by multivariable Cox proportional hazard models, and the predictive value was determined by a receiver-operating characteristic (ROC) curve.

RESULTS

During the follow-up with a median time of 3 years, 179 (6.5%) cases of MACCEs and 47 (1.7%) cases of CV death or TVMI were recorded. Patients with a high TyG index (> 9.10) and a high SHR (> 0.87) showed a significantly increased risk of CV death/TVMI (TyG index: HR 4.23, 95% CI 1.58-11.37; SHR: HR 5.14, 95% CI 1.89-13.98) and MACCEs (TyG index: HR 2.47, 95% CI 1.54-3.97; SHR: HR 2.91, 95% CI 1.84-4.60) compared with those with a low Tyg index and a low SHR (TyG < 8.56, SHR < 0.76). The area under the curve (AUC) values were 0.623 (TyG index) and 0.589 (SHR) for CV death/TVMI and 0.659 (TyG index) and 0.624 (SHR) for MACCEs. Furthermore, patients with both a high TyG index and a high SHR showed the highest risk of clinical outcomes among patients with different levels of these two biomarkers, and the AUC for the TyG-SHR combination was larger than the TyG index alone in predicting MACCE risk.

CONCLUSIONS

The study revealed that a high TyG index and a high SHR were significantly correlated with poor prognosis in patients with CTO and suggested that these two biomarkers are reliable in predicting long-term prognosis in CTO patients.