Coronary artery bypass grafting (CABG) remains a cornerstone in the care of patients with severe coronary artery disease, especially in those with multivessel involvement or diabetes.¹

Traditionally, CABG is conducted utilizing cardiopulmonary bypass (CPB), also known as on-pump CABG, which offers a bloodless and immobile field to enable exact anastomoses. However, CPB use has been associated to a range of potential issues, including systemic inflammatory response, coagulopathies, renal failure, and neurocognitive deterioration.^{2, 3} In response to these concerns, off-pump CABG (OPCAB), which operates on a beating heart instead of CPB, has emerged as a viable alternative. OPCAB is said to lower perioperative morbidity by reducing the systemic effects of CPB, which could assist high-risk patients ^4,5. Several randomized controlled trials and observational studies have investigated the comparative effectiveness of OPCAB and on-pump CABG, yielding inconsistent results. Some studies imply that OPCAB is related with less perioperative bleeding and a decreased incidence of renal dysfunction,^6,7 although others find no meaningful difference in early mortality or complications.⁸

The applicability and outcomes of CABG techniques can be influenced by patient selection, surgical expertise, and institutional protocols. In India, where the burden of coronary artery disease is rising and patient demographics vary considerably from Western populations, there is a need for context-specific data to inform clinical decision-making^9,10.

This study compares the early postoperative outcomes of off-pump versus on-pump CABG. The findings could serve to improve surgical methods in the local population and drive evidence-based practice. India, with its diverse population and varying access to healthcare resources, is a suitable site for evaluating the feasibility and effectiveness of off-pump CABG. Understanding the outcomes in this environment will provide useful information about the effectiveness of various surgical methods in Indian tertiary care settings. We analysed the 30-day short-term results of patients who received both on- and off-pump CABG.

OBJECTIVES :

Primary Objective:

To assess the short-term results (mortality, morbidity, complications, and recovery) of patients receiving off-pump vs on-pump CABG at VMMC & SJH (Vardhman Mahavir Medical College & Safdarjung Hospital), New Delhi, from January 2023 to January 2024.

Secondary Objectives:

To assess complications such as myocardial infarction, stroke, arrhythmias, infection, and renal failure in both groups, as well as recovery characteristics such as ICU stay.

Study Design:

In order to compare the results of two patient groups—those who had off-pump CABG and those who had on-pump CABG between January 2023 and January 2024—this study used a retrospective cohort design. Information was taken from follow-up visits, surgical logs, and patient records.

Study Setting:

The study took place at VMMC & SJH, New Delhi, which is a tertiary care hospital. The hospital has a specialized cardiac surgery unit, a dedicated ICU for cardiac patients, and a well-established post-operative care system.

Inclusion Criteria:

- Adult patients (≥18 years) who underwent either off-pump or on-pump CABG between January 2023 and January 2024.

- Both elective and emergency CABG surgeries.

- Patients undergoing single or multi-vessel CABG.

- Patients with a minimum follow-up of 1 month post-surgery.

Exclusion Criteria:

- Patients undergoing “combined surgeries” (e.g., valve replacement, heart transplantation) at the time of CABG.

- Patients under 18 years of age.

- Incomplete medical records or lack of follow-up data.

Data Collection:

1. Demographic and Clinical Characteristics:

   - Age, gender, comorbidities (e.g., hypertension, diabetes, hyperlipidemia), smoking, and family history of CAD.

   - Pre-operative data: coronary angiography findings, left ventricular ejection fraction (LVEF), number of vessels involved.

2. Surgical Approach:

   - Surgical technique: off-pump vs. on-pump CABG.

   - Intraoperative variables: type and number of grafts, choice of graft (internal mammary artery, radial artery, saphenous vein), and use of other medications.

   - Surgical duration, intraoperative complications, and the use of hemodynamic support.

3. Post-Operative Outcomes:

   - Immediate complications: renal failure, respiratory failure, cardiac arrest, bleeding, arrhythmias, and infections.

   - Recovery metrics: ICU stay, ventilator time.

   - Mortality rates: in-hospital mortality and 30-day mortality.

SAMPLE SIZE

In the study “Off pump vs on pump coronary artery bypass grafting: Perioperative complications and early clinical outcomes” by Ayman El Naggar, et.al,¹¹ it was reported that 20% of participants in on-pump group had post operative bleeding while in off pump group it was observed in 3%. Taking these values as reference with 5% error, 80% power and 10% attrition, the minimum sample size is 54 per group. As there are two groups, the total sample size is 108.

STATISTICAL ANALYSIS

The STATA 15.0 program was used for statistical analysis after the data was imported into MS-Excel.  The data's normality was assessed using the Shapiro-Wilk test.  The study employed descriptive statistics, presenting continuous data as mean ± SD and categorical variables as frequency and percentage.  The Mann-Whitney test was used to compare continuous variables with study groups, including age, BMI, time to extubation, and others.  Pre-, intra-, and post-operative data were examples of categorical variables that were compared between research groups using the Chi-square test.  The significance level was set at less than 0.05.

The study included 108 patients who had coronary artery bypass grafting (CABG), with 54 in the off-pump and 54 in the on-pump group. The dataset used for analysis had no missing values.

Table 1: Baseline characteristics of the study participants

As shown in Table 1, the average age of patients in the off-pump group was comparable to that of the on-pump group. The gender distribution was similar in both groups. There were no statistically significant age or gender differences between the groups.

Table 2: History of the study participants

Table 2 presents the history of the study participants. The two groups showed no significant differences in terms of family history of coronary artery disease, hypertension, diabetes, smoking status, or other coexisting conditions. This shows that the off-pump and on-pump groups have comparable baseline risk profiles.

Table 3: Comparison of pre-operative parameters amongst study groups

As indicated Table 3 shows no significant difference between the two groups in preoperative clinical indicators such as ejection fraction, serum creatinine levels, hemoglobin concentration, and lipid profiles. This suggests that both groups had similar prior cardiac and metabolic condition.

Table 4: Comparison of intra-operative parameters amongst study groups

Table 4 describes the intraoperative findings. There were no statistically significant differences between the groups with regard to graft count, surgery length, or cross-clamp time (where relevant for the on-pump group). The intraoperative blood loss and transfusion requirements were comparable.

Table 5: Comparison of post-operative parameters amongst study groups

Table 5 presents the postoperative parameters. Most postoperative variables, including ventilation duration, ICU stay, bleeding rates were similar across two groups. However, the on-pump group used considerably more inotropes (p < 0.05). This shows a higher need for immediate postoperative hemodynamic support in patients following on-pump CABG.

Table 6: Comparison of clinical outcome amongst study groups

Table 6 demonstrates that the two groups had no statistically significant difference in early postoperative outcomes such as 30-day mortality, myocardial infarction, stroke, renal failure, and wound infection. Both surgical procedures demonstrated comparable safety in terms of early clinical results.

The goal of this study was to compare early postoperative outcomes for off-pump vs on-pump coronary artery bypass grafting (CABG) procedures conducted at a tertiary care hospital in New Delhi, India.Our findings show that both approaches produce similar early outcomes in terms of death, serious complications, and hospital stay, with the only statistically significant difference being lower inotrope usage in the off-pump group. This shows that avoiding cardiopulmonary bypass (CPB) has a hemodynamic benefit.

Previous randomized controlled studies and meta-analyses have produced conflicting results regarding the comparative efficacy Off-pump and on-pump CABG. The ROOBY and CORONARY trials, two major multicentre studies found no significant differences in short-term mortality, stroke, or myocardial infarction between the two techniques.^{12, 13} Our findings are consistent with previous research, demonstrating that off-pump CABG is a safe and effective alternative to the traditional on-pump surgery for certain patients.

Our investigation found that the off-pump group required less inotropic support, which is consistent with earlier publications that have highlighted the hemodynamic stability and reduced myocardial damage associated with the off-pump technique.^{14, 15} Avoiding CPB decreases the systemic inflammatory response syndrome (SIRS) and cardiac reperfusion damage associated with pump use, perhaps contributing to improved perioperative hemodynamics.¹⁶

Importantly, our study did not observe significant differences in ventilation time, ICU or hospital stay, renal dysfunction between the groups. These findings challenge earlier studies suggesting Significant advantages of off-pump CABG in terms of reduced postoperative morbidity,^17,18 and instead support more recent meta-analyses indicating near equivalence of both techniques in most early clinical outcomes.¹⁹

Patient demographics and baseline risk variables, such as age and gender, comorbidities, and preoperative left ventricular function, were comparable between the groups in our study, minimizing the influence of confounding variables. Furthermore, the uniformity in intraoperative variables, including the number of grafts indicates consistent surgical practice across groups.

While the off-pump approach may offer theoretical advantages in high-risk populations—such as the elderly or those with severe aortic calcification—these benefits were not the primary focus of this study. Our findings suggest that in a general surgical cohort, off-pump CABG does not significantly improve short-term clinical outcomes compared to the on-pump technique, but may still offer a lower requirement for inotropic support postoperatively.

Limitations

The single-center, non-randomized design of this study has limitations, including the possibility of selection bias. Although the groups' baseline characteristics were similar, unmeasured confounders cannot be totally dismissed. Furthermore, the study focused primarily on early postoperative outcomes; Long-term graft patency, quality of life, and survival statistics were not evaluated, but require future examination.

Off-pump CABG is a safe and effective alternative to on-pump CABG, with comparable early postoperative outcomes. The reduced usage of inotropes in the off-pump group shows a potential hemodynamic advantage in the immediate postoperative term. These findings support the use of either technique, based on surgical expertise and individual patient factors, with off-pump CABG offering possible benefits in selected cases.

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