Predicting outcomes in patients with low ejection fraction undergoing coronary artery bypass graft.

Introduction: Reduced left ventricular ejection fraction (LVEF) is a well-known predictor of adverse events after cardiac surgery. We aimed to assess the outcomes in patients with low LVEF undergoing coronary artery bypass graft. Methods: In this retrospective cohort, we included all patients with left ventricular ejection fraction ≤ 40 who underwent coronary artery bypass grafting between March 2007 and March 2016 (with a median follow-up of nine years) at Tehran Heart Center. Demographics and clinical characteristics were extracted from the data registry. Akaike information criterion (AIC) was used. The univariate Cox regression was performed. We investigated the predictors of mortality and major adverse cardiac and cerebrovascular events (MACCE) using Cox multivariable regression. Results: In total, 5,532 cases (79 % male) with a mean age of 65.58 were included in the study. The nine-year overall survival was calculated at 68 %, and more than half of the patients had MACCE (55 %). In adjusted multivariable Cox regression analysis, moderate to severe mitral valve regurgitation, glomerular filtration rate ≤ 60, mild right ventricular dysfunction, and valvular heart disease independently predicted higher mortality. The abovementioned predictors and peripheral vascular disease significantly increased MACCE. Conclusion: Our study indicates the clinical significance of mitral regurgitation, valvular heart disease, and renal function in patients with low ejection fraction treated by coronary artery bypass grafting surgery. Identifying predictors of adverse events can help with clinical decision-making and risk stratification, ultimately improving patient outcomes.

Coronavirus Disease 2019 Pandemic and Reduced Surgical Site Infection After Cardiac Surgery: A Potential Blessing in Disguise.

Background: The coronavirus disease 2019 (COVID-19) pandemic has brought about drastic hygienic measures, one upside of which might be the mitigated occurrence of surgical site infection (SSI). This study investigated the association of the pandemic with SSI occurrence after cardiac surgeries. Patients and Methods: From 2014 to 2022, patients undergoing cardiac surgery were included and categorized into pre-pandemic and during-pandemic groups. Surgical site infections were classified into harvest-site, superficial sternal, and complex sternal infection. Multiple logistic regression and inverse probability weighting assessed the association of the pandemic with SSI. Results: Among a total of 26,143 patients, 793 SSIs occurred. The during-pandemic patients were younger (61.87 ± 10.58 vs. 65.64 ± 11.82) with a higher male proportion (70.1% vs. 67.4%) and a higher prevalence of all studied comorbidities/risk factors (expect cigarette smoking). Total SSI rate decreased substantially from 3.3% before COVID-19 to 1.8% afterward (p < 0.001). Inverse probability weights analyses evinced an independent association of the pandemic with a reduced risk of total (adjusted odds ratio [OR]; 0.59; 95% confidence interval [CI], 0.45-0.78), harvest-site (adjusted OR, 0.36; 95% CI, 0.19-0.70), and superficial sternal infection (adjusted OR, 0.60; 95% CI, 0.43-0.81). No significant association was observed with complex sternal site infection (adjusted OR, 1.05; 95% CI, 0.55-2.01). Multivariable regression recapitulated these findings. Conclusions: The COVID-19 pandemic independently pertained to more than a 40% reduction in SSI occurrence, particularly affecting harvest-site and superficial sternal infections. However, there remains the possibility of the implications of other known and unknown confounders on the observed association. To some extent, the decrease in SSIs after the pandemic can be justified by reinforced hygienic precautions, emphasizing the necessity of extending the adherence to these measurements into the post-COVID-19 era to maintain the status quo.

Sex-based association between high-density lipoprotein cholesterol and adverse outcomes after coronary artery bypass grafting.

BACKGROUND: High-density lipoprotein cholesterol (HDL-C) is shown to be an independent protective factor against coronary artery diseases (CAD). Yet there are limited studies focusing on the association between HDL-C and coronary artery bypass graft (CABG) surgery outcomes. HYPOTHESIS: Low levels of HDL-C are associated with higher incidence of adverse outcomes in patients undergoing CABG. METHODS: This registry-based study included 17,772 patients who underwent elective isolated CABG between 2007 and 2017. Patients were classified into low and desirable HDL-C groups based on their serum HDL-C levels at admission and were followed for one-year post-surgery. The study population included 13,321 patients with low HDL-C and 4,451 with desirable HDL-C. proportional hazard Cox models were performed to evaluate the association between HDL-C levels and incidence of mortality as well as major adverse cardiovascular and cerebrovascular events (MACCE), while adjusting for potential confounders. Moreover, participants were stratified based on sex and the association was also investigated in each subgroup separately. RESULTS: No significant difference was found between the groups regarding incidence of both mortality and MACCE, after adjusting with Inverse Probability Weighting (IPW) [HR (95%CI): 0.84 (0.46-1.53), p-value:0.575 and HR (95% CI): 0.91 (0.56-1.50), p-value:0.733, respectively]. According to the sex-based subgroup analysis, no significant association was observed after adjustment with IPW analysis. However, as we examined the association between the interaction of HDL-C levels, sex and cardiovascular outcomes, we found a significant association (HR;1.19 (95%CI: 1.04-1.45); p = 0.030). CONCLUSION: HDL-C level was not associated with either mortality or MACCE during one year after CABG procedure. Sex-based analysis showed that in males, HDL-C is significantly more protective against these outcomes, compared to females. Further studies are necessary to elucidate the exact mechanisms mediating such association.

Heart surgery over two decades: what we have learned about results and changing risks.

OBJECTIVES: Using the cardiac surgery database is of high importance in referral centers and can lead to a better quality of care for patients. Tehran Heart Center (THC) is a cardiovascular referral center that was inaugurated in 2001. In this report, we aimed to present the third report of trends in patients' cardiovascular risk factors and surgical procedures from 2002 to 2021 that have been gathered for all THC patients. METHODS: This serial cross-sectional study was conducted at Tehran Heart Center from 2002 to 2021. All patients undergoing cardiac surgeries were eligible to enter the study (N = 63,974). Those with miscellaneous types of surgeries were excluded (N = 9556). The distribution of cardiac surgeries (including isolated coronary artery bypass graft (CABG), isolated valve, and CABG + valve surgeries) and their respective in-hospital mortality were recorded. Furthermore, 20-year trends in the prevalence of various cardiovascular risk factors (CVRFs) among the following groups were evaluated: a) isolated CABG, b) aortic valve replacement/repair for aortic stenosis (AS/AVR/r), and c) isolated other valve surgeries (IVS). RESULTS: A total of 54,418 patients (male: 70.7%, age: 62.7 ± 10.8 years) comprised the final study population, with 84.5% prevalence of isolated CABG. Overall, the AS/AVR/r group was in between the CABG and IVS groups concerning CVRFs distribution. Excluding some exceptions for the AS/AVR/r group (in which the small sample size (N = 909) precluded observing a clear trend), all studied CVRFs demonstrated an overall rising trend from 2002 to 2021 in all three groups. Regarding in-hospital mortality, the highest rate was recorded as 4.0% in 2020, while the lowest rate was 2.0% in 2001. CONCLUSIONS: Isolated CABG remained the most frequent procedure in THC. Notable, increasing trends in CVRFs were observed during this 20-year period and across various types of cardiac surgeries, which highlights the clinical and policy-making implications of our findings.

Factors Affecting Late Atrial Fibrillation and Its Association With Coronary Artery Bypass Outcomes.

BACKGROUND: Although predictors and outcomes of postoperative atrial fibrillation (POAF) are well studied, evidence is lacking concerning postdischarge late/recurrent atrial fibrillation (AF). This study evaluated factors affecting late/recurrent AF and its association with coronary artery bypass grafting (CABG) outcomes in a real-world setting. METHODS: From 2012 through 2016, 5175 patients were included. Independent factors associated with late/recurrent AF were identified in a competing risk setting. Cox proportional hazard regression was used to evaluate the association between late/recurrent AF and study outcomes, consisting of all-cause mortality, major adverse cardio-cerebrovascular events, acute coronary syndrome, cerebrovascular events, and heart failure admissions. RESULTS: During a median follow-up of 60 months (quartile 1-quartile 3, 59.3-60.7 months), late/recurrent AF developed in 85 patients (1.64%). Independent factors associated with late/recurrent AF were age (subdistribution hazard ratio [sHR], 1.04; 95% CI, 1.02-1.07), left-ventricular ejection fraction (sHR, 0.97; 95% CI, 0.95-0.99), length of stay (sHR, 1.02; 95% CI, 1.01-1.04), and POAF (sHR, 4.02; 95% CI, 2.50-6.45). Late/recurrent AF was not significantly associated with all-cause mortality and major adverse cardio-cerebrovascular events at unadjusted or adjusted levels (adjusted hazard ratio, 0.80 [95% CI, 0.50-1.28] and 0.74 [95% CI, 0.48-1.13], respectively). Nevertheless, it significantly increased the unadjusted risk of cerebrovascular events (hazard ratio, 2.28; 95% CI, 01.07-4.87), which disappeared after adjustments. CONCLUSIONS: Patients with advanced age, a lower left-ventricular ejection fraction, and POAF are more likely to have late/recurrent clinical AF. Albeit counterintuitive, late/recurrent AF was not independently associated with worse midterm post-CABG outcomes. These observations need to be further elucidated in larger-scale studies and interpreted in the context of a developing country with limited resources for late AF surveillance.

Time-varying effect of postoperative cholesterol profile on long-term outcomes of isolated coronary artery bypass graft surgery.

BACKGROUND: Controlling cholesterol levels is one of the primary goals of preventing atherosclerotic plaque progression in patients undergoing coronary artery bypass graft (CABG) surgery. This study aimed to investigate the impact of serum cholesterol profile at multiple time points following isolated CABG surgery on long-term patient outcomes. METHOD: This retrospective cohort study was conducted on the admission and follow-up data of isolated CABG patients from the Tehran Heart Center registry between 2009 and 2016. The association of low-density lipoprotein (LDL), high-density lipoprotein (HDL), and their ratio as an atherogenic index with major adverse cardiac and cerebrovascular events (MACCE) and all-cause mortality were evaluated using time-varying survival analysis methods. RESULT: A total of 18657 patients were included in this analysis. After adjusting for known confounding factors, no significant difference in all-cause mortality and MACCE was observed at different LDL levels. The incidence of acute coronary syndrome (ACS) in patients with LDL > 100 mg/dl and LDL < 50 mg/dl was significantly higher than in the control group (P-value = 0.004 and 0.04, respectively). The incidence of cerebrovascular accidents (CVA) at LDL > 100 mg/dl was also significantly higher compared to the control group (P -value = 0.033). Lower HDL levels were significantly associated with a higher MACCE (P -value < 0.001), all-cause mortality (P -value < 0.001), ACS (P -value = 0.00), and CVA (P -value = 0.014). The atherogenic index was also directly related to MACCE and all its components (all P-values < 0.001). CONCLUSION: LDL/HDL ratio is suggested as a better marker for secondary prevention goals compared to LDL alone in patients undergoing CABG surgery.

Coronary Artery Bypass Graft Surgery After Primary Percutaneous Coronary Intervention in Patients With ST-Elevation Myocardial Infarction.

OBJECTIVE: To determine whether primary percutaneous coronary intervention (PPCI) is associated with adverse outcomes following coronary artery bypass graft (CABG) among patients with ST-elevation myocardial infarction (STEMI). METHODS: Patients presenting with acute STEMI who underwent CABG between September 2015 and November 2020 were included. Among 354 patients, 222 (62.7%) underwent PPCI prior to CABG (PPCI+CABG group) and were compared with the rest of the patients (CABG only group). The effects of PPCI on primary endpoints---including in-hospital mortality, length of stay (LOS), and bleeding events---were investigated using the stabilised inverse probability weighting method (S-IPW). Further, in-hospital mortality in various PPCI subgroups was analysed using univariable regression. RESULTS: Patients with and without PPCI were comparable regarding their baseline and surgical characteristics, except that those without PPCI were more likely to have left-main disease (29.5% vs 16.2%, p-value=0.003). Among the PPCI+CABG group, 3.6% mortality and 55.9% bleeding events occurred, and the LOS was 7 [5-10] days. The respective figures for the CABG only group were 4.5%, 50.8%, and 7 [6-10.5] days. Primary percutaneous coronary intervention, as a whole, was not significantly associated with either morality (S-IPW odds ratio (S-IPW OR) 0.61; p=0.393), LOS logarithm (S-IPW ß -0.050; p=0.403), or bleeding events (S-IPW OR 1.06; p=0.821). Nevertheless, the unadjusted mortality risk was significantly higher in complicated PPCIs compared with the CABG only group (OR 7.50, 95% CI 2.03-27.77); it was also higher among some other PPCI subgroups, albeit non-significantly. CONCLUSION: This study found that PPCI did not confer additional risk regarding in-hospital mortality, LOS, or bleeding among patients with acute STEMI who underwent CABG. However, some PPCI subgroups, especially those with complicated PPCI, were at increased risk.

A realistic approach to evaluating the effect of baseline lipid profile in postcoronary artery bypass grafting surgery.

BACKGROUND: There are still many uncertainties in the association between lipid profile and postcoronary artery bypass grafting (CABG) outcomes. Although simplifying the association to linear equations makes it understandable but cannot explain many findings. HYPOTHESIS: There is a nonlinear associatin between lipid profile indices and adverse outcomes after CABG. METHODS: A total of 17 555 patients who underwent isolated CABG between 2005 and 2016 were evaluated. During the median follow-up of 75.24 months, the Restricted Cubic Splines (RCS) estimated from the Cox regression model adjusted for all possible confounders was applied to show a nonlinear relationship of lipid profile contents with the "ln hazard ratio" of mortality and major cerebro-cardiac events (MACCE). RESULTS: The relationship between LDL-C and HDL-C with all-cause mortality was nonlinear (nonlinear p were .004 and <.001, respectively). The relationship between remnant cholesterol and all-cause mortality was linear (linearity p = .023). Among men, those in the highest LDL-C level (Q4, LDL-C > 114) and those in the lowest HDL-C level (Q1, HDL-C < 30) showed a significantly higher risk of all-cause mortality compared to other groups (compared with Q3, LDL-C Q4, HR = 1.16, 95% confidence interval [CI]:1.02-1.26, p = .014; HDL-C Q1, HR = 1.14, 95% CI: 1.01-1.31, p = .041). Female patients in the lowest HDL-C level (Q1, HDL-C < 30) showed a significantly higher (compared with Q3, HR = 1.14, 95% CI:1.01-1.31, p = .028) and those in the highest HDL-C level (Q4, HDL-C > 43) showed a significantly lower (compared with Q3, HR = 0.74, 95% CI:0.58-0.98, p = .019) risk of all-cause mortality. CONCLUSION: Determining a universal cut off for components of lipid profile may be misleading and should better be revised. Extreme values (very low or very high) for HDL-C and LDL-C have different effects on cardiovascular outcomes.

7-year outcomes in diabetic patients after coronary artery bypass graft in a developing country.

BACKGROUND: Revascularization in diabetic patients with coronary artery disease remains a challenge in cardiology practice. Although clinical trials have reported the mid-term superiority of coronary artery bypass grafting (CABG) surgery over percutaneous coronary intervention in these patients, little is known about the long-term outcomes of CABG in diabetic patients compared to non-diabetics, particularly in developing countries. METHODS: Between 2007 and 2016, we recruited all patients who underwent isolated CABG in a tertiary care cardiovascular center in a developing country. The patients were followed at 3-6 months and 12 months after surgery, and then annually. The study endpoints were 7-year all-cause mortality and major adverse cardiac and cerebrovascular events (MACCE). RESULTS: Of 23,873 patients (17,529 males, mean age 65.67 years) who underwent CABG, 9227 (38.65%) patients were diagnosed with diabetes. After adjustment for potential confounders, patients with diabetes experienced a 31% increase in MACCE seven years after surgery compared to the non-diabetic patients (HR = 1.31, 95% CI: 1.25-1.38, P-value < 0.0001). Meanwhile, diabetes contributes to a 52% increase in the risk of all-cause mortality after CABG (HR = 1.52, 95% CI: 1.42-1.61, P-value < 0.0001). CONCLUSIONS: Our study showed a higher risk of all-cause mortality and MACCE at seven years in diabetic patients undergoing isolated CABG. The outcomes in the studied center in a developing country were comparable to western centers. The high incidence of adverse outcomes in the long term in diabetic patients implies that not only short-term but long-term measures should be taken to improve the CABG outcomes in this challenging patient population.

Early and mid-term outcomes of off-pump versus on-pump coronary artery bypass surgery in patients with triple-vessel coronary artery disease: a randomized controlled trial.

BACKGROUND AND AIM OF THE STUDY: Several studies have compared early and late outcomes of on-pump coronary artery bypass grafting (CABG) and off-pump CABG. However, there is still an ongoing debate on this matter, especially in patients with triple-vessel coronary artery disease (3VD). METHODS: We randomly assigned 274 consecutive patients with 3VD to two equal groups to undergo on-pump CABG or off-pump CABG. The primary outcome was major adverse cardiac and cerebrovascular events (MACCE), including all-cause mortality, acute coronary syndrome, stroke or transient ischemic attack, and the need for repeat revascularization. The secondary outcomes were postoperative infection, ventilation time, ICU admission duration, hospital stay length, and renal failure after surgery. RESULTS: The median follow-up duration was 31.2 months (range 24.6-35.2 months). The mean age of patients was 61.4 ± 9.3 years (range: 38-86), and 207 (78.7%) were men. There were 15 (11.2%) and 9 (7.0%) MACCE occurrences in on-pump and off-pump groups, respectively (P value = 0.23). MACCE components including all-cause death, non-fatal MI, CVA, and revascularization did not significantly differ between on-pump and off-pump groups. We observed no difference in the occurrence of MACCE between off-pump and on-pump groups in multivariable regression analysis (HR = 0.57; 95% CI 0.24-1.32; P value = 0.192). There were no statistical differences in postoperative outcomes between the off-pump and on-pump CABG groups. CONCLUSIONS: Off-pump CABG is an equal option to on-pump CABG for 3VD patients with similar rates of MACCE and postoperative complications incidence when surgery is performed in the same setting by an expert surgeon in both methods. (IRCT20190120042428N1).

Opium consumption and long-term outcomes of CABG surgery in patients without modifiable risk factors.

Background: The question about the significance of opium consumption as a coronary artery disease (CAD) risk factor still remains open. The present study aimed to evaluate the association between opium consumption and long term outcomes of coronary artery bypass grafting (CABG) in patients without standard modifiable CAD risk factors (SMuRFs; hypertension, diabetes, dyslipidemia, and smoking). Methods: In this registry-based design, we included 23,688 patients with CAD who underwent isolated CABG between January 2006 to December 2016. Outcomes were compared in two groups; with and without SMuRF. The main outcomes were all-cause mortality, fatal and nonfatal cerebrovascular events (MACCE). Inverse probability weighting (IPW) adjusted Cox's proportional hazards (PH) model was used to evaluate the effect of opium on post-op outcomes. Results: During 133,593 person-years of follow-up, opium consumption was associated with increased risk of mortality in both patients with and without SMuRFs (weighted Hazard Ratio (HR)s: 1.248 [1.009, 1.574] and 1.410 [1.008, 2.038], respectively). There was no association between opium consumption and fatal and non-fatal MACCE in patients without SMuRF (HR = 1.027 [0.762-1.383], HR 0.700 [0.438-1.118]). Opium consumption was associated with earlier age of CABG in both groups; 2.77 (1.68, 3.85) years in SMuRF-less and 1.70 (1.11, 2.38) years in patients with SMuRFs. Conclusion: Opium users not only undergo CABG at younger ages but also have a higher rate of mortality regardless of the presence of traditional CAD risk factors. Conversely, the risk of MACCE is only higher in patients with at least one modifiable CAD risk factor.

Off-pump versus on-pump coronary artery bypass graft surgery outcomes in patients with severe left ventricle dysfunction: inverse probability weighted study.

OBJECTIVE: In this study we aimed to compare on-pump and off-pump coronary artery bypass grafting (CABG) outcomes in patients presented with low left ventricular ejection fraction (EF) as a high-risk group of patients. METHODS: In this registry-based study from 2014 and 2016, all patients with severe left ventricular dysfunction (EF less than 35%) were included and followed until 2020. The median follow-up period was 47.83 [38.41, 55.19] months. Off pump CABG (OPCABG) was compared with on-pump CABG (ONCABG) in terms of mid-term non-fatal cardiovascular events (CVEs) and all-cause mortality. Propensity score method (with inverse probability weighting technique) was used to compare these two groups. RESULTS: From 14,237 patients who underwent isolated CABG, 2055 patients with EF ≤ 35% were included; 1705 in ONCABG and 350 patients in OPCABG groups. Although OPCABG was associated with lower risk of 30-days mortality (Odds Ratio [OR]: 0.021; Confidence Interval [CI] 95% [0.01, 0.05], P < 0.001); there was no significant difference between OPCABG and ONCABG in term of mid-term mortality and non-fatal CVEs ((Hazard ratio [HR]: 0.822; 95%CI [0.605, 1.112], p = 0.208) and (HR: 1.246; 95%CI [0.805, 1.929], p = 0.324), respectively). Patients with more than three traditional coronary artery disease risk factors, had more favorable outcomes (in terms of mid-term mortality) if underwent OPCABG (HR: 0.420; 95%CI [0.178, 0.992], p = 0.048). CONCLUSION: OPCABG was associated with lower risk of 30-days mortality; however, mid-term outcomes were comparable in both OPCABG and ONCABG techniques.

BMI modifies HDL-C effects on coronary artery bypass grafting outcomes.

BACKGROUND: Despite the recognized implications of high-density lipoprotein cholesterol (HDL-C) in cardiovascular diseases, the role of body mass index (BMI) in HDL-C association with cardiovascular outcomes remains unclear. This study investigated the possible modifying implications of BMI on the correlation between HDL-C and coronary artery bypass grafting (CABG) outcomes. METHODS: The present cohort included isolated CABG patients (median follow-up: 76.58 [75.79-77.38] months). The participants were classified into three groups: 18.5 ≤ BMI < 25 (normal), 25 ≤ BMI < 30 (overweight), and 30 ≤ BMI < 35 (obese) kg/m2. Cox proportional hazard models (CPHs) and restricted cubic splines (RCSs) were applied to evaluate the relationship between HDL-C and all-cause mortality as well as major adverse cardio-cerebrovascular events (MACCEs) in different BMI categories. RESULTS: This study enrolled a total of 15,639 patients. Considering the final Cox analysis among the normal and overweight groups, HDL-C ≥ 60 was a significant protective factor compared to 40 < HDL-C < 60 for all-cause mortality (adjusted hazard ratio (aHR): 0.47, P: 0.027; and aHR: 0.64, P: 0.007, respectively). However, the protective effect of HDL-C ≥ 60 was no longer observed among patients with 30 ≤ BMI < 35 (aHR: 1.16, P = 0.668). RCS trend analyses recapitulated these findings; among 30 ≤ BMI < 35, no uniform inverse linear association was observed; after approximately HDL-C≈55, its increase was no longer associated with reduced mortality risk. RCS analyses on MACCE revealed a plateau effect followed by a modest rise in overweight and obese patients from HDL-C = 40 onward (nonlinear association). CONCLUSIONS: Very high HDL-C (≥ 60 mg/dL) was not related to better outcomes among obese CABG patients. Furthermore, HDL-C was related to the post-CABG outcomes in a nonlinear manner, and the magnitude of its effects also differed across BMI subgroups.

The association between different body mass index levels and midterm surgical revascularization outcomes.

BACKGROUND: There are conflicting results regarding the relationship between overweight/obesity and the outcomes of coronary artery bypass graft surgery (CABG), termed "the obesity paradox". This study aimed to evaluate the effects of body mass index (BMI) on the midterm outcomes of CABG. METHODS: This historical cohort study included all patients who underwent isolated CABG at our center between 2007 and 2016. The patients were divided into five categories based on their preoperative BMIs (kg/m2): 18.5≤BMI<25, 25≤BMI<30, 30≤BMI<35, 35≤BMI<40, and BMI≥40. Patients with BMIs below 18.5 kg/m2 were excluded. The endpoints of this study were all-cause mortality and major adverse cardio-cerebrovascular events (MACCEs), comprising acute coronary syndromes, cerebrovascular accidents, and all-cause mortality at five years. For the assessment of the linearity of the relationship between continuous BMI and the outcomes, plots for time varying hazard ratio of BMI with outcomes were provided. RESULTS: Of 17 751 patients (BMI = 27.30 ±4.17 kg/m2) who underwent isolated CABG at our center, 17 602 patients (mean age = 61.16±9.47 y, 75.4% male) were included in this study. Multivariable analysis demonstrated that patients with pre-obesity and normal weight had similar outcomes, whereas patients with preoperative BMIs exceeding 30 kg/m2 kg/m2 had a significantly higher risk of 5-year all-cause mortality and 5-year MACCEs than those with pre-obesity. Additionally, a positive association existed between obesity degree and all-cause mortality and MACCEs. Further, BMIs of 40 kg/m2 or higher showed a trend toward higher MACCE risks (adjusted hazard ratio, 1.32; 95% confidence interval, 0.89 to 1.95), possibly due to the small sample size. A nonlinear, albeit negligible, association was also found between continuous BMI and the study endpoints. CONCLUSIONS: Our findings suggest that preoperative obesity (BMI>30 kg/m2) in patients who survive early after CABG is associated with an increased risk of 5-year all-cause mortality and 5-year MACCEs. These findings indicate that physicians and cardiac surgeons should encourage patients with high BMIs to reduce weight for risk modification.

Machine learning algorithms for predicting mortality after coronary artery bypass grafting.

Background: As the era of big data analytics unfolds, machine learning (ML) might be a promising tool for predicting clinical outcomes. This study aimed to evaluate the predictive ability of ML models for estimating mortality after coronary artery bypass grafting (CABG). Materials and methods: Various baseline and follow-up features were obtained from the CABG data registry, established in 2005 at Tehran Heart Center. After selecting key variables using the random forest method, prediction models were developed using: Logistic Regression (LR), Support Vector Machine (SVM), Naïve Bayes (NB), K-Nearest Neighbors (KNN), Extreme Gradient Boosting (XGBoost), and Random Forest (RF) algorithms. Area Under the Curve (AUC) and other indices were used to assess the performance. Results: A total of 16,850 patients with isolated CABG (mean age: 67.34 ± 9.67 years) were included. Among them, 16,620 had one-year follow-up, from which 468 died. Eleven features were chosen to train the models. Total ventilation hours and left ventricular ejection fraction were by far the most predictive factors of mortality. All the models had AUC > 0.7 (acceptable performance) for 1-year mortality. Nonetheless, LR (AUC = 0.811) and XGBoost (AUC = 0.792) outperformed NB (AUC = 0.783), RF (AUC = 0.783), SVM (AUC = 0.738), and KNN (AUC = 0.715). The trend was similar for two-to-five-year mortality, with LR demonstrating the highest predictive ability. Conclusion: Various ML models showed acceptable performance for estimating CABG mortality, with LR illustrating the highest prediction performance. These models can help clinicians make decisions according to the risk of mortality in patients undergoing CABG.

Prognostic significance of positive family history in outcomes after coronary artery bypass grafting: Do we need to update our assumptions?

BACKGROUND: Recent research suggests a protective role for positive family history of premature cardiovascular disease (FHpCVD) in patients undergoing coronary artery bypass grafting. We aimed to further investigate this unlikely association. METHODS: In this registry-based cohort study, patients who underwent first-time non-emergent coronary bypass surgery at Tehran Heart Center between 2007 and 2016 were included. Patients with and without FHpCVD were compared in terms of all-cause mortality and first non-fatal cardiovascular events (CVEs) comprising non-fatal acute coronary syndrome, non-fatal stroke or transient ischemic attack, and repeat coronary revascularization. RESULTS: A total of 13,156 patients were included (mean age 60.83 ± 9.57, 74.5% male), among which 2684 (20.4%) patients had FHpCVD. Median follow-up was 77.7 months. FHpCVD was weakly associated with reduced all-cause mortality using inverse probability weight (IPW) method (hazard ratio [HR] = 0.853; 95% confidence interval [CI] 0.730-0.997; P = 0.046), and not associated with non-fatal CVEs considering death as the competing event (sub-distribution HR [SHR] = 1.124; 95% CI 0.999-1.265; P = 0.053). Within a subgroup of patients without previous myocardial infarction or revascularization (7403 cases; 56.3%), FHpCVD was associated with lower mortality (HR = 0.700; 95% CI 0.548-0.894; P = 0.004) and higher non-fatal CVEs (SHR = 1.197; 95% CI 1.019-1.405; P = 0.028), whereas among patients with previous coronary events, there was no association between FHpCVD and outcomes. CONCLUSIONS: FHpCVD was associated with lower all-cause mortality but higher non-fatal CVEs, especially in those without prior coronary events. Such discordance calls for caution in assuming a protective role for FHpCVD. The prognostic significance of FHpCVD needs further evaluation among surgical patients.

Effect of postoperative atrial fibrillation on early and mid-term outcomes of coronary artery bypass graft surgery.

OBJECTIVES: The long-term prognostic role of postoperative atrial fibrillation (POAF) in cardiovascular outcomes in patients undergoing cardiac surgery is uncertain. Our goal was to investigate the impact of new-onset POAF on midterm adverse cardiovascular events after coronary artery bypass graft (CABG) surgery. METHODS: We performed a retrospective cohort study of patients who underwent isolated CABG without a preoperative history of atrial fibrillation/flutter. POAF was defined as episodes of AF lasting ≥30 s during the hospitalization period. The effect of POAF on midterm all-cause mortality and cerebrovascular accidents/transient ischaemic attacks (CVA/TIA) was assessed using a Cox proportional hazard regression model in a competing risk setting. Additional analyses were performed on patients surviving an event-free early postoperative period (i.e. within 30 postoperative days after the index operation). RESULTS: A total of 9,310 patients were followed for a median duration of 48.7 months. New-onset POAF was associated with an increased risk of midterm all-cause mortality (HR = 1.648, 95% confidence interval: 1.402-1.937; P < 0.001) and CVA/TIA (subdistribution-HR = 1.635, 1.233-2.167; P = 0.001). After excluding patients who died during the early postoperative period, POAF remained significantly associated with higher late all-cause mortality (HR = 1.518, 1.273-1.811; P < 0.001). However, the risk of late CVA/TIA in patients who survived the early postoperative period without having a stroke was similar between those with and without POAF (subdistribution-HR = 1.174, 0.797-1.729; P = 0.418). CONCLUSIONS: New-onset POAF after CABG is associated with an increased risk of midterm overall mortality and stroke. However, late stroke risk is likely similar between patients with and without POAF who survive an event-free early postoperative period.

Effect of Different Blood Groups on Long-Term Outcomes of Surgical Revascularisation.

BACKGROUND: ABO blood groups are considered to be associated with cardiovascular disease. Nonetheless, the definite effect of ABO blood groups on the clinical outcome of coronary artery bypass graft surgery (CABG) is still undetermined. We evaluated whether ABO blood groups can predict long-term major adverse cardiocerebrovascular events (MACCE) in CABG patients. METHOD: In this retrospective cohort study, we retrieved the clinical files of eligible patients treated with isolated CABG in our hospital between March 2007 and March 2016. We divided the patients into four ABO subgroups. The primary study endpoints were the occurrence of all-cause mortality and MACCE during long-term follow-ups. We used Cox regression survival analysis to define the association of ABO blood groups with the occurrence of MACCE. RESULTS: Of 17,892 patients who underwent isolated CABG, 17,713 (mean age, 61.19±9.47 years, 74.6% male) were successfully followed, and their data used in the final analysis. Our multivariable analysis demonstrated that patients with different blood groups had similar 5-year mortality and 5-year MACCE. CONCLUSIONS: Our findings suggest that in patients who underwent CABG, ABO blood groups were not associated with long-term MACCE.

Sex difference in the risk factor distributions and outcomes after coronary artery bypass graft surgery in the young population.

OBJECTIVES: Coronary artery disease is becoming a major health concern in the young population. Male and female patients may experience different journeys after coronary artery disease events. We aimed to evaluate risk factors and compare outcomes between young male and female patients undergoing coronary artery bypass graft surgery (CABG). METHODS: In this registry-based large sample size study, patients undergoing isolated CABG at a young age (premature isolated CABG) between 2007 and 2016 were included and followed up until 2020. Premature was defined as women and men younger than 55 years old. The main end points of the study were 7-year all-cause mortality and 7-year major adverse cardiovascular and cerebrovascular events (MACCEs). RESULTS: Of a total of 24 428 patients who underwent CABG, 7217 patients (men-to-women ratio ≈4:1) with premature isolated CABG were included. The median follow-up duration was 78.5 months (75.2-81.6 months). The prevalence rates of diabetes mellitus, hypertension, dyslipidaemia and obesity were significantly higher in women than in men (58.3% vs 28.6%, 64.2% vs 38.5%, 69.7% vs 55.3% and 44.7 vs 23.9, respectively; all Ps < 0.05). The risk factor burden (mean of the risk factor count per year) was also higher among the female population. Diabetes mellitus was the common mortality predictor between men and women. In the subgroup analysis (interaction analysis in the adjusted model), hypertensive females had a higher rate of MACCE and a higher rate of mortality than hypertensive males; however, this difference was not significant in the non-hypertensive population. Opium addiction was a strong predictor of MACCE and all-cause mortality among men. Female patients had a higher rate of 7-year MACCE (hazard ratio, 1.33; 95% confidence interval, 1.16-1.51) and a higher rate of 7-year all-cause mortality (hazard ratio, 1.23; 95% confidence interval, 0.98-1.53). CONCLUSIONS: The risk factor profile and predictors of outcomes were different between our female and male patients. Women carried a higher risk of events and mortality after CABG at a young age.

Significance of preoperative left ventricular ejection fraction in 5-year outcome after isolated CABG.

BACKGROUND: Pre-operative ejection fraction (EF) and comorbidities affect post-op outcomes. We aimed to compare the mortality and adverse events of patients with different baseline EF and also to evaluate the distribution of comorbidities in each EF group. METHODS: A total of 20,937 patients who underwent isolated coronary artery bypass graft (CABG) surgery from January 2006 to December 2016 was included. Patients were divided into three groups based on their pre-operative left ventricular EF as follows; (1) Normal: EF ≥ 50%; (2) Mild to moderately reduced: 50% < EF ≤ 35%; and (3) Severely reduced: EF < 35%. The backward elimination method was considered for multivariate Cox-regression analysis to locate predictors of mortality and non-fatal cerebro-cardiovascular events (CCVEs). The median follow-up time was 5.61 [3.12-8.0] years. RESULTS: The mean age in the total population was 60.94 ± 9.51 years and 73.6% of the total population was male. Diabetes mellitus was the common risk factor of mortality and CCVE in all EF groups. Impaired renal function (GFR < 60 ml/min) was associated with a higher risk of mortality after CABG regardless of EF level. The median 5-year mortality rate in patients with normal EF, mild-moderately reduced EF and severely reduced EF were 9.5%, 12.8%, and 22.7% respectively (P < 0.001). Although the trend of CCVEs was higher in severe left ventricle (LV) dysfunction, it was not statistically significant (p = 0.071). CONCLUSION: Patients with severely reduced EF are at higher risk of mortality after CABG compared to those with higher EF levels; however, the rate of CCVEs may not be necessarily higher after adjustment for multiple pre-operative comorbidities.