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Background: Risk stratification for patients undergoing coronary artery bypass surgery (CABG) for left main coronary artery (LMCA) disease is essential for informed decision-making. This study explored the potential of machine learning (ML) methods to identify key risk factors associated with mortality in this patient group., Methods: This retrospective cohort study was conducted on 866 patients from the Gulf Left Main Registry who presented between 2015 and 2019. The study outcome was hospital all-cause mortality. Various machine learning models [logistic regression, random forest (RF), k-nearest neighbor, support vector machine, naïve Bayes, multilayer perception, boosting] were used to predict mortality, and their performance was measured using accuracy, precision, recall, F1 score, and area under the receiver operator characteristic curve (AUC)., Results: Nonsurvivors had significantly greater EuroSCORE II values (1.84 (10.08-3.67) vs. 4.75 (2.54-9.53) %, P <0.001 for survivors and nonsurvivors, respectively). The EuroSCORE II score significantly predicted hospital mortality (OR: 1.13 (95% CI: 1.09-1.18), P <0.001), with an AUC of 0.736. RF achieved the best ML performance (accuracy=98, precision=100, recall=97, and F1 score=98). Explainable artificial intelligence using SHAP demonstrated the most important features as follows: preoperative lactate level, emergency surgery, chronic kidney disease (CKD), NSTEMI, nonsmoking status, and sex. QLattice identified lactate and CKD as the most important factors for predicting hospital mortality this patient group., Conclusion: This study demonstrates the potential of ML, particularly the Random Forest, to accurately predict hospital mortality in patients undergoing CABG for LMCA disease and its superiority over traditional methods. The key risk factors identified, including preoperative lactate levels, emergency surgery, chronic kidney disease, NSTEMI, nonsmoking status, and sex, provide valuable insights for risk stratification and informed decision-making in this high-risk patient population. Additionally, incorporating newly identified risk factors into future risk-scoring systems can further improve mortality prediction accuracy., (Copyright © 2024 The Author(s). Published by Wolters Kluwer Health, Inc.)

Background: Preoperative intra-aortic balloon pump (IABP) before coronary artery bypass grafting (CABG) could improve operative outcomes by augmenting the diastolic coronary blood flow. Data on preoperative IABP use in patients with left-main coronary artery (LMCA) disease are limited. This study aimed to characterize patients who received preoperative IABP before CABG for LMCA and evaluate its effect on postoperative outcomes., Methods: This multicenter retrospective cohort study that included consecutive 914 patients who underwent CABG for unprotected LMCA disease from January 2015 to December 2019 in 14 tertiary referral centers. Patients were grouped according to the preoperative IABP insertion into patients with IABP (n=101) and without IABP (n=813). Propensity score matching adjusting for preoperative variables, with 1:1 match and a caliber of 0.03 identified 80 matched pairs. The primary outcomes used in propensity score matching were cardiac mortality and major adverse cardiac and cerebrovascular events (MACCE)., Results: IABP was commonly inserted in patients with previous myocardial infarction (MI), chronic kidney disease, peripheral arterial disease, and congestive heart failure. IABP patients had higher EuroSCORE [ES >8%: 95 (11.86%) vs. 40 (39.60%), P<0.001] and SYNTAX {29 [interquartile range (IQR) 25-35] vs. 33 (IQR 26-36); P=0.02} scores. Preoperative cardiogenic shock and arrhythmia were more prevalent in patients with IABP, while acute coronary syndrome was more prevalent in patients without IABP. After matching, there was no difference in vasoactive inotropic score between groups [3.5 (IQR 1-7.5) vs. 6 (IQR 1-13.5), P=0.06], and lactate levels were nonsignificantly higher in patients with IABP [2.4 (IQR 1.4-4.5) vs. 3.1 (IQR 1.05-7.75), P=0.05]. There were no differences between groups in acute kidney injury [20 (25%) vs. 26 (32.5%), P=0.34], cerebrovascular accidents [3 (3.75%) vs. 4 (5%), P>0.99], heart failure [5 (6.25%) vs. 7 (8.75%), P=0.75], MI [7 (8.75%) vs. 8 (10%), P>0.99], major adverse cardiac and cerebrovascular events [10 (12.5%) vs. 17 (21.25%), P=0.21], and cardiac mortality [6 (7.50%) vs. 14 (17.50%), P=0.09]. Patients who received IABP had longer ventilation times [8.5 (IQR 6-23) vs. 15.5 (IQR 5-50.5) h, P=0.03] and intensive care unit (ICU) stays [3 (IQR 2-5) vs. 4 (IQR 2-7.5) days, P=0.01]., Conclusions: Preoperative IABP in patients with LMCA might not be associated with reduced cardiac mortality or hospital complications. IABP could increase the duration of mechanical ventilation and ICU stay, and its use should be individualized for each patient., Competing Interests: Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://cdt.amegroups.com/article/view/10.21037/cdt-23-418/coif). The authors have no conflicts of interest to declare., (2024 Cardiovascular Diagnosis and Therapy. All rights reserved.)

Background: The use of dual antiplatelet therapy (DAPT) after coronary revascularization for left-main disease is still debated. The study aimed to characterize patients who received dual versus single antiplatelet therapy (SAPT) after coronary artery bypass grafting (CABG) for unprotected left-main disease and compare the outcomes of those patients., Results: This multicenter retrospective cohort study included 551 patients who were grouped into 2 groups: patients who received SAPT (n = 150) and those who received DAPT (n = 401). There were no differences in age ( P = 0.451), gender ( P = 0.063), smoking ( P = 0.941), diabetes mellitus ( P = 0.773), history of myocardial infarction ( P = 0.709), chronic kidney disease ( P = 0.615), atrial fibrillation ( P = 0.306), or cerebrovascular accident ( P = 0.550) between patients who received SAPT versus DAPT. DAPTs were more commonly used in patients with acute coronary syndrome [87 (58%) vs. 273 (68.08%); P = 0.027], after off-pump CABG [12 (8%) vs. 73 (18.2%); P = 0.003] and in patients with radial artery grafts [1 (0.67%) vs. 32 (7.98%); P < 0.001]. While SAPTs were more commonly used in patients with low ejection fraction [55 (36.67%) vs. 61 (15.21%); P < 0.001] and in patients with postoperative acute kidney injury [27 (18%) vs. 37 (9.23%); P = 0.004]. The attributed treatment effect of DAPT for follow-up major adverse cerebrovascular and cardiac events was not significantly different from that of SAPT [β, -2.08 (95% confidence interval (CI), -20.8-16.7); P = 0.828]. The attributed treatment effect of DAPT on follow-up all-cause mortality was not significantly different from that of SAPT [β, 4.12 (CI, -11.1-19.32); P = 0.595]. There was no difference in bleeding between groups ( P = 0.666)., Conclusions: DAPTs were more commonly used in patients with acute coronary syndrome, after off-pump CABG, and with radial artery grafts. SAPTs were more commonly used in patients with low ejection fraction and acute kidney injury. Patients on DAPT after CABG for left-main disease had comparable major adverse cerebrovascular and cardiac events and survival to patients on SAPT, with no difference in bleeding events., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Currently, gender is not considered in the choice of the revascularization strategy for patients with unprotected left main coronary artery (ULMCA) disease. This study analyzed the effect of gender on the outcomes of percutaneous coronary intervention (PCI) vs coronary artery bypass grafting (CABG) in patients with ULMCA disease. Females who had PCI (n = 328) were compared with females who had CABG (n = 132) and PCI in males (n = 894) was compared with CABG (n = 784). Females with CABG had higher overall hospital mortality and major adverse cardiovascular events (MACE) than females with PCI. Male patients with CABG had higher MACE; however, mortality did not differ between males with CABG vs PCI. In female patients, follow-up mortality was significantly higher in CABG patients, and target lesion revascularization was higher in patients with PCI. Male patients had no difference in mortality and MACE between groups; however, MI was higher with CABG, and congestive heart failure was higher with PCI. In conclusion, women with ULMCA disease treated with PCI could have better survival with lower MACE compared with CABG. These differences were not evident in males treated with either CABG or PCI. PCI could be the preferred revascularization strategy in women with ULMCA disease., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Introduction Cardiovascular disease (CVD), including coronary artery disease (CAD), is a leading global cause of death. Chronic kidney disease (CKD) is a significant risk factor, particularly in data-scarce Saudi Arabia, due to shared risk factors. A study aims to assess the CVD-CKD relationship, identifying clinical characteristics and risk factors to improve prevention and care in this context, filling a knowledge gap in Saudi Arabia's healthcare map. Methodology It is a single-center retrospective study aimed at evaluating the relationship between cardiovascular disease and chronic kidney disease, conducted between January 2023 and October 2023. Data was sourced from patient files using a data sheet based on a previous study. The data was cleaned in MS Excel (Redmond, USA) and analyzed in IBM Corp. Released 2022. IBM SPSS Statistics for Windows, Version 29.0. Armonk, NY: IBM Corp. Results Our study contains predominantly males (61%), aged 61-80 (54.1%), with a normal body mass index (BMI) (<25) (61.5%) and a high prevalence of smoking (72.3%). Diabetes, hypertension, and smoking were prevalent risk factors. The relationship between CAD severity, renal dysfunction, and ejection fraction (EF) was explored, emphasizing the association between declining renal function and more advanced CAD stages, as well as the decline in estimated glomerular filtration rate (eGFR) with decreasing EF. Age, smoking, CAD, and decreasing EF were linked to renal dysfunction, while smoking, stroke history, peripheral vascular disease (PVD), BMI, and decreasing EF were associated with CAD stage severity. Conclusion Our study explored that as CAD severity increases, renal function decreases, showing both CVD and CKD connected with each other, and a similar correlation occurs between decreasing EF and decreasing eGFR, revealing significant associations with various risk factors. Further research is warranted to explore potential interventions aimed at mitigating the synergistic impact of CVD and CKD on patient morbidity and mortality., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2023, Elheet et al.)

The optimal stenting strategy for unprotected left main coronary artery (ULMCA) disease remains debated. This retrospective observational study (Gulf Left Main Registry) analyzed the outcomes of 1 vs 2 stents in patients with unprotected left main percutaneous coronary intervention (PCI). Overall, 1222 patients were evaluated; 173 had 1 stent and 1049 had 2 stents. The 2-stent group was older with more comorbidities, higher mean SYNTAX scores, and more distal bifurcation lesions. In the 1-stent group, in-hospital events were significant for major bleeding, and better mean creatinine clearance. At median follow-up of 20 months, the 1-stent group was more likely to have target lesion revascularization (TLR). Total mortality was numerically lower in the 1-stent group (.00% vs 2.10%); however, this was not statistically significant ( P =.068). Our analysis demonstrates the benefits of a 2-stent approach for ULMCA patients with high SYNTAX scores and lesions in both major side branches, while the potential benefit of a 1-stent approach for less complex ULMCA was also observed. Further studies with longer follow-up are needed to definitively demonstrate the optimal approach.

Background: The optimal revascularization strategy in patients with left main coronary artery (LMCA) disease in the emergency setting is still controversial. Thus, we aimed to compare the outcomes of percutaneous coronary interventions (PCI) vs. coronary artery bypass grafting (CABG) in patients with and without emergent LMCA disease., Methods: This retrospective cohort study included 2138 patients recruited from 14 centers between 2015 and 2019. We compared patients with emergent LMCA revascularization who underwent PCI (n = 264) to patients who underwent CABG (n = 196) and patients with non-emergent LMCA revascularization with PCI (n = 958) to those who underwent CABG (n = 720). The study outcomes were in-hospital and follow-up all-cause mortality and major adverse cardiovascular and cerebrovascular events (MACCE)., Results: Emergency PCI patients were older and had a significantly higher prevalence of chronic kidney disease, lower ejection fraction, and higher EuroSCORE than CABG patients. CABG patients had significantly higher SYNTAX scores, multivessel disease, and ostial lesions. In patients presenting with arrest, PCI had significantly lower MACCE (P = 0.017) and in-hospital mortality (P = 0.016) than CABG. In non-emergent revascularization, PCI was associated with lower MACCE in patients with low (P = 0.015) and intermediate (P < 0.001) EuroSCORE. PCI was associated with lower MACCE in patients with low (P = 0.002) and intermediate (P = 0.008) SYNTAX scores. In non-emergent revascularization, PCI was associated with reduced hospital mortality in patients with intermediate (P = 0.001) and high (P = 0.002) EuroSCORE compared to CABG. PCI was associated with lower hospital mortality in patients with low (P = 0.031) and intermediate (P = 0.001) SYNTAX scores. At a median follow-up time of 20 months (IQR: 10-37), emergency PCI had lower MACCE compared to CABG [HR: 0.30 (95% CI 0.14-0.66), P < 0.003], with no significant difference in all-cause mortality between emergency PCI and CABG [HR: 1.18 (95% CI 0.23-6.08), P = 0.845]., Conclusions: PCI could be advantageous over CABG in revascularizing LMCA disease in emergencies. PCI could be preferred for revascularization of non-emergent LMCA in patients with intermediate EuroSCORE and low and intermediate SYNTAX scores., (© 2023. The Author(s).)

Introduction: The aim of this study was to evaluate the effects of baseline anemia and anemia following revascularization on outcomes in patients with unprotected left main coronary artery (ULMCA) disease., Methods: This was a retrospective, multicenter, observational study conducted between January 2015 and December 2019. The data on patients with ULMCA who underwent revascularization through percutaneous coronary intervention (PCI) or coronary artery bypass graft (CABG) were stratified by the hemoglobin level at baseline into anemic and non-anemic groups to compare in-hospital events. The pre-discharge hemoglobin following revascularization was categorized into very low (&lt;80 g/L for men and women), low (≥80 and ≤119 g/L for women and ≤129 g/L for men), and normal (≥130 g/L for men and ≥120 g/L for women) to assess impact on follow-up outcomes., Results: A total of 2,138 patients were included, 796 (37.2%) of whom had anemia at baseline. A total of 319 developed anemia after revascularization and moved from being non-anemic at baseline to anemic at discharge. There was no difference in hospital major adverse cardiac and cerebrovascular event (MACCE) and mortality between CABG and PCI in anemic patients. At a median follow-up time of 20 months (interquartile range [IQR]: 27), patients with pre-discharge anemia who underwent PCI had a higher incidence of congestive heart failure (CHF) (p &lt; 0.0001), and those who underwent CABG had significantly higher follow-up mortality (HR: 9.85 (95% CI: 2.53-38.43), p = 0.001)., Conclusion: In this Gulf LM study, baseline anemia had no impact upon in-hospital MACCE and total mortality following revascularization (PCI or CABG). However, pre-discharge anemia is associated with worse outcomes after ULMCA disease revascularization, with significantly higher all-cause mortality in patients who had CABG, and a higher incidence of CHF in PCI patients, at a median follow-up time of 20 months (IQR: 27)., (© 2023 S. Karger AG, Basel.)

Coronary artery bypass grafting (CABG) and percutaneous coronary intervention (PCI) in revascularization of left main coronary artery (LMCA) disease has been evaluated in previous studies. However, there has been minimal study of the relationship between co-existing non-coronary atherosclerosis (NCA) and LMCA disease revascularization. We aim to examine this relationship. The Gulf-LM study is a retrospective analysis of unprotected LMCA revascularization cases undergoing PCI with second generation drug-eluting stent vs CABG across 14 centers within 3 Gulf countries between January 2015 and December 2019. A total of 2138 patients were included, 381 with coexisting NCA and 1757 without. Outcomes examined included major adverse cardiovascular and cerebrovascular events (MACCE), cardiac and non-cardiac death, and all bleeding. In patients with NCA, preexisting myocardial infarction and congestive heart failure were more common, with PCI being the most common revascularization strategy. A statistically significant reduction in in-hospital MACCE and all bleeding was noted in patients with NCA undergoing PCI as compared to CABG. At a median follow-up of 15 months, MACCE and major bleeding outcomes continued to favor the PCI group, though no such difference was identified between revascularization strategies in patients without NCA.In this multicenter retrospective study of patients with and without NCA who require revascularization (PCI and CABG) for unprotected LMCA disease, PCI demonstrated a better clinical outcome in MACCE both in-hospital and during the short-term follow-up in patients with NCA. However, no such difference was observed in patients without NCA., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Aims: The impact of left ventricular dysfunction on clinical outcomes following revascularization is not well established in patients with unprotected left main coronary artery disease (ULMCA). In this study, we evaluated the impact of left ventricular ejection fraction (LVEF) on clinical outcomes of patients with ULMCA requiring revascularization with percutaneous coronary intervention (PCI) compared with coronary artery bypass graft (CABG)., Methods: The details of the design, methods, end points, and relevant definitions are outlined in the Gulf Left Main Registry: a retrospective, observational study conducted between January 2015 and December 2019 across 14 centres in 3 Gulf countries. In this study, the data on patients with ULMCA who underwent revascularization through PCI or CABG were stratified by LVEF into three main subgroups; low (l-LVEF <40%), mid-range (m-LVEF 40-49%), and preserved (p-LVEF ≥50%). Primary outcomes were hospital major adverse cardiovascular and cerebrovascular events (MACCE) and mortality and follow-up MACCE and mortality., Results: A total of 2137 patients were included; 1221 underwent PCI and 916 had CABG. During hospitalization, MACCE was significantly higher in patients with l-LVEF [(10.10%), P = 0.005] and m-LVEF [(10.80%), P = 0.009], whereas total mortality was higher in patients with m-LVEF [(7.40%), P = 0.009] and p-LVEF [(7.10%), P = 0.045] who underwent CABG. There was no mortality difference between groups in patients with l-LVEF. At a median follow-up of 15 months, there was no difference in MACCE and total mortality between patients who underwent CABG or PCI with p-LVEF and m-LVEF., Conclusion: CABG was associated with higher in-hospital events. Hospital mortality in patients with l-LVEF was comparable between CABG and PCI. At 15 months' follow-up, PCI could have an advantage in decreasing MACCE in patients with l-LVEF., (Copyright © 2022 Italian Federation of Cardiology - I.F.C. All rights reserved.)

Introduction: The evidence about the optimal revascularization strategy in patients with left main coronary artery (LMCA) disease and impaired renal function is limited. Thus, we aimed to compare the outcomes of LMCA disease revascularization (percutaneous coronary intervention [PCI] vs. coronary artery bypass grafting [CABG]) in patients with and without impaired renal function., Methods: This retrospective cohort study included 2,138 patients recruited from 14 centers between 2015 and 2,019. We compared patients with impaired renal function who had PCI (n= 316) to those who had CABG (n = 121) and compared patients with normal renal function who had PCI (n = 906) to those who had CABG (n = 795). The study outcomes were in-hospital and follow-up major adverse cardiovascular and cerebrovascular events (MACCE)., Results: Multivariable logistic regression analysis showed that the risk of in-hospital MACCE was significantly higher in CABG compared to PCI in patients with impaired renal function (odds ratio [OR]: 8.13 [95% CI: 4.19-15.76], p &lt; 0.001) and normal renal function (OR: 2.59 [95% CI: 1.79-3.73]; p &lt; 0.001). There were no differences in follow-up MACCE between CABG and PCI in patients with impaired renal function (HR: 1.14 [95% CI: 0.71-1.81], p = 0.585) and normal renal function (HR: 1.12 [0.90-1.39], p = 0.312)., Conclusions: PCI could have an advantage over CABG in revascularization of LMCA disease in patients with impaired renal function regarding in-hospital MACCE. The follow-up MACCE was comparable between PCI and CABG in patients with impaired and normal renal function., (© 2023 The Author(s). Published by S. Karger AG, Basel.)

Background: Real-world data for managing patients with diabetes and left main coronary artery (LMCA) disease are scarce. We compared percutaneous coronary intervention (PCI) outcomes versus coronary artery bypass grafting (CABG) in diabetes and LMCA disease patients., Methods: We retrospectively studied patients with LMCA presented to 14 centers from 2015 to 2019. The study included 2138 patients with unprotected LMCA disease; 1468 (68.7 %) had diabetes. Patients were grouped into; diabetes with PCI (n = 804) or CABG (n = 664) and non-diabetes with PCI (n = 418) or CABG (n = 252)., Results: In diabetes, cardiac (34 (5.1 %) vs. 22 (2.7 %); P = 0.016), non-cardiac (13 (2 %) vs. 6 (0.7 %); P = 0.027) and total hospital mortality (47 (7.1 %) vs. 28 (3.5 %); P = 0.0019), myocardial infarction (45 (6.8 %) vs. 11 (1.4 %); P = 0.001), cerebrovascular events (25 (3.8 %) vs. 12 (1.5 %); P = 0.005) and minor bleeding (65 (9.8 %) vs. 50 (6.2 %); P = 0.006) were significantly higher in CABG patients compared to PCI; respectively. The median follow-up time was 20 (10-37) months. In diabetes, total mortality was higher in CABG (P = 0.001) while congestive heart failure was higher in PCI (P = 0.001). There were no differences in major adverse cerebrovascular events and target lesion revascularization between PCI and CABG. Predictors of mortality in diabetes were high anatomical SYNTAX, peripheral arterial disease, chronic kidney disease, and cardiogenic shock., Conclusions: In this multicenter retrospective study, we found no significant difference in clinical outcomes during the short-term follow-up between PCI with second-generation DES and CABG except for lower total mortality and a higher rate of congestive heart failure in PCI group of patients. Randomized trials to characterize patients who could benefit from each treatment option are needed., Competing Interests: Declaration of competing interest None., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Coronary artery bypass surgery (CABG) has been the standard of care for revascularization for patients with obstructive unprotected left main coronary disease (ULMCA). There have been multiple randomized and registry data demonstrating the technical and clinical efficacy of PCI in certain patients with ULMCA. The purpose of this study is to evaluate clinical outcomes of ULMCA PCI as compared to CABG in patients requiring revascularization in three Gulf countries. All ULMCA cases treated by PCI with DES versus CABG were retrospectively identified from 14 centers in 3 Arab Gulf countries (KSA, UAE, and Bahrain) from January 2015 to December 2019. In total, 2138 patients were included: 1222 were treated with PCI versus 916 with CABG. Patients undergoing PCI were older, and had higher comorbidities and mean European System for Cardiac Operative Risk Evaluation (EuroSCORE). Aborted cardiac arrest and cardiogenic shock were reported more in the PCI group at hospital presentation. In addition, lower ejection fractions were reported in the PCI group. In hospital mortality and major adverse cardiovascular and cerebrovascular events (MACCE) occurred more in patients undergoing CABG than PCI. At median follow-up of 15 months (interquartile range, 30), no difference was observed in freedom from revascularization, MACCE, or total mortality between those treated with PCI and CABG. While findings are similar to Western data registries, continued follow-up will be needed to ascertain whether this pattern continues into latter years., (Copyright © 2021 Elsevier Inc. All rights reserved.)

The COVID-19 pandemic had significant impact on health care worldwide which has led to a reduction in all elective admissions and management of patients through virtual care. The purpose of this study is to assess changes in STEMI volumes, door to reperfusion, and the time from the onset of symptoms until reperfusion therapy, and in-hospital events between the pre-COVID-19 (PC) and after COVID-19 (AC) period. All acute ST-segment elevation myocardial infarction (STEMI) cases were retrospectively identified from 16 centers in the Kingdom of Saudi Arabia during the COVID-19 period from January 01 to April 30, 2020. These cases were compared to a pre-COVID period from January 01 to April 30, 2018 and 2019. One thousand seven hundred and eighty-five patients with a mean age 56.3 (SD ± 12.4) years, 88.3% were male. During COVID-19 Pandemic the total STEMI volumes was reduced (28%, n = 500), STEMI volumes for those treated with reperfusion therapy was reduced too (27.6%, n= 450). Door to balloon time < 90 minutes was achieved in (73.1%, no = 307) during 2020. Timing from the onset of symptoms to the balloon of more than 12 hours was higher during 2020 comparing to pre-COVID 19 years (17.2% vs <3%, respectively). There were no differences between the AC and PC period with respect to in-hospital events and the length of hospital stay. There was a reduction in the STEMI volumes during 2020. Our data reflected the standard of care for STEMI patients continued during the COVID-19 pandemic while demonstrating patients delayed presenting to the hospital., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Background: Femoral arterial sheath thrombosis and distal embolization are well-recognized complications of cardiac catheterization but the occlusion is extremely rare. Heparinized saline flushes are used during diagnostic coronary angiography to prevent thrombus formation within the sheath lumen. However, the use of prophylactic intravenous heparin following the femoral arterial sheath insertion is controversial. The aim of this study is to evaluate the effectiveness of 2000 units of intravenous heparin bolus in comparison to a saline placebo on the thrombus formation within the arterial sheath during the diagnostic coronary angiography., Methods: Eligible patients were randomized to receive either a study drug or placebo at the time of femoral sheath insertion. The sheath was aspirated and flushed for any presence of thrombus after each catheter exchange and at the end of the procedure. Five milliliters of blood were extracted and visualized on clean gauze followed by a saline flush. The primary end-point was the effectiveness of the study drug on reducing the incidence of sheath-thrombus formation., Results: Three hundred and twenty patients were randomized into two arms. Three hundred and four patients were analyzed: 147 patients in heparin arm and 157 patients in placebo arm after exclusion of 13 patients in heparin arm and three in placebo arm because of incomplete reports. The baseline characteristics were similar and sheath-thrombi formation was observed in 20% of the total cohort. Of the heparin arm, 12% (19 patients) developed sheath-thrombus formation, whereas 26% (42 patients) in the placebo arm, p-value = 0.002. An adjusted logistic regression model showed that the only predictor for the sheath-thrombus formation was the study drug (i.e. heparin). The odds ratio of developing a thrombus in the control arm was 2.5 (95% CI: 1.4-4.5, p = 0.003). There were no bleeding events observed., Conclusion: The risk of thrombus formation is significant and intravenous heparin significantly reduced thrombus formation during diagnostic coronary angiography, with no excess bleeding events.