Preoperative Prediction of Early Mortality in Patients with Low Ejection Fraction Undergoing Coronary Artery Bypass Grafting

Surgical Management of Ischemic Heart Disease Patients With Left Ventricular Dysfunction in Lower-Middle-Income Countries: Our Strategies and Experience at the Medical Teaching Institute-Hayatabad Medical Complex (MTI-HMC) Peshawar, Pakistan

Introduction and objectives Severe left ventricular dysfunction (LVD) in coronary artery disease (CAD) is linked to high risks and limited outcomes. Coronary artery bypass grafting (CABG) remains a key surgical intervention for these patients. This study aimed to assess hospital and short-term outcomes in patients with severe LVD undergoing isolated CABG and identify predictors of adverse outcomes. Methodology We conducted a retrospective study of 454 patients who underwent CABG for CAD with significant LVD at Hayatabad Medical Complex between 2018 and 2024. Data were extracted from clinical records and analyzed statistically to evaluate outcomes and predictors. Results The study included 454 patients with a mean age of 58.14 ± 9.576 years and a mean ejection fraction of 35.59 ± 3.996%. There were 396 (87.2%) male patients with common comorbidities, including hypertension (122, 26.9%), diabetes mellitus (88, 19.4%), and smoking (39, 8.6%). Intraoperative findings showed a mean cardiopulmonary bypass (CPB) time of 155.94 ± 38.120 minutes, with 451 (99.3%) achieving LIMA (left internal mammary artery) to LAD (left anterior descending artery) revascularization. Postoperative in-hospital mortality was 21 (4.6%), re-intubation occurred in 18 (4.0%), and arrhythmias were observed in 26 (5.7%). Wound infections were minimal (444 (97.8%) without infection), and 406 (89.4%) underwent elective CABG, while nine (2.0%) had emergent CABG, mostly due to ventricular septal rupture. Conclusion CABG remains a vital surgical intervention for patients with severe LVD, offering favorable short-term outcomes despite the inherent risks. Key factors contributing to these results include comprehensive myocardial revascularization, effective use of internal mammary artery grafting, and advanced myocardial protection strategies. This study highlights the potential of CABG to improve survival and functional outcomes in this high-risk population.

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.

Six-years survival and predictors of mortality after CABG using cold vs. warm blood cardioplegia in elective and emergent settings

Background

The aim of this study was to determine whether intermittent warm blood cardioplegia (IWC) is associated with comparable myocardial protection compared to cold blood cardioplegia (ICC) in patients undergoing elective vs. emergent CABG procedures.

Methods

Out of 2292 consecutive patients who underwent isolated on-pump CABG surgery using cardioplegic arrest either with ICC or IWC between January 2008 and December 2010, 247 consecutive emergent patients were identified and consecutively matched 1:2 with elective patients based on gender, age (<50 years, 50–70 years, >70 years) and ejection fraction (<40 %, 40–50 %, >50 %). Perioperative outcomes and long-term mortality were compared between ICC and IWC strategies and predictors for 30-day mortality and perioperative myocardial injury were identified in both elective and emergent subgroups of patients.

Results

Preoperative demographics and baseline characteristics, logistic Euroscore, CPB-time, number of distal anastomoses and LIMA-use were comparable. Aortic cross clamp time was significantly longer in the IWC-group regardless of the urgency of the procedure (p = 0.05 and p = 0.015 for emergent and elective settings). There were no significant differences regarding ICU-stay, ventilation time, total blood loss and need for dialysis. The overall 30-day, 1-, 3- and 6-year survival of the entire patient cohort was 93.7, 91.8, 90.4 and 89.1 %, respectively, with significantly better outcomes when operated electively (p < 0.001) but no differences between ICC and IWC both in elective (p = 0.857) and emergent (p = 0.741) subgroups. Multivariate analysis did not identify the type of cardioplegia as a predictor for 30-day mortality and for perioperative myocardial injury. However, independent factors predictive of 30-day mortality were: EF < 40 % (OR 3.66; 95 % CI: 1.79–7.52; p < 0.001), atrial fibrillation (OR 3.33; 95 % CI: 1.49-7.47; p < 0.003), peripheral artery disease (OR 2.51; 95 % CI: 1.13–5.55; p < 0.023) and COPD (OR 0.26; 95 % CI: 1.05–6.21; p < 0.038); predictors for perioperative myocardial infarction were EF < 40 % (OR 2.04; 95 % CI: 1.32–3.15; p < 0.001), preoperative IABP support (OR 3.68; 95 % CI: 1.34-10.13; p < 0.012), and hemofiltration (OR 3.61; 95 % CI: 2.22–5.87; p < 0.001).

Conclusion

Although the aortic cross clamp time was prolonged in the IWC group our results confirm effective myocardial protection under IWC, regardless of the urgency of the procedure. We suggest that intermittent warm cardioplegia in emergent CABG setting is a low-cost alternative and safe. It is associated with similar long-term outcomes both in elective and emergent settings compared to intermittent cold cardioplegia.

Tidal lung recruitment and exhaled nitric oxide during coronary artery bypass grafting in patients with and without chronic obstructive pulmonary disease

BACKGROUND

We studied the occurrence of intraoperative tidal alveolar recruitment/derecruitment, exhaled nitric oxide (eNO), and lung dysfunction in patients with and without chronic obstructive pulmonary disease (COPD) undergoing coronary artery bypass grafting (CABG).

METHODS

We performed a prospective observational physiological study at a university hospital. Respiratory mechanics, shunt, and eNO were assessed in moderate COPD patients undergoing on-pump (n = 12) and off-pump (n = 8) CABG and on-pump controls (n = 8) before sternotomy (baseline), after sternotomy and before cardiopulmonary bypass (CPB), and following CPB before and after chest closure. Respiratory system resistance (R (rs)), elastance (E (rs)), and stress index (to quantify tidal recruitment) were estimated using regression analysis. eNO was measured with chemiluminescence.

RESULTS

Mechanical evidence of tidal recruitment/derecruitment (stress index <1.0) was observed in all patients, with stress index <0.8 in 29% of measurements. Rrs in on-pump COPD was larger than in controls (p < 0.05). Ers increased in controls from baseline to end of surgery (19.4 ± 5.5 to 27.0 ± 8.5 ml cm H(2)O(-1), p < 0.01), associated with increased shunt (p < 0.05). Neither Ers nor shunt increased significantly in the COPD on-pump group. eNO was comparable in the control (11.7 ± 7.0 ppb) and COPD on-pump (9.9 ± 6.8 ppb) groups at baseline, and decreased similarly by 29% at end of surgery(p < 0.05). Changes in eNO were not correlated to changes in lung function.

CONCLUSIONS

Tidal recruitment/derecruitment occurs frequently during CABG and represents a risk for ventilator-associated lung injury. eNO changes are consistent with small airway injury, including that from tidal recruitment injury. However, those changes are not correlated with respiratory dysfunction. Controls have higher susceptibility to develop complete lung derecruitment.