|Year : 2022 | Volume
| Issue : 2 | Page : 68-73
Prospective analysis of early outcomes of off-pump coronary artery bypass in high-risk patients and role of EuroSCORE-II
Darshak Patel1, Mrinal Patel1, ZS Meharwal2
1 Department of Cardiovascular and Thoracic Surgery, U. N. Mehta Institute of Cardiology and Research Center (Affiliated to B. J. Medical College), Ahmedabad, Gujarat, India
2 Department of Cardiovascular Surgery, Fortis Escort Heart Institute, Okhala, New Delhi, India
|Date of Submission||05-Mar-2022|
|Date of Decision||20-Mar-2022|
|Date of Acceptance||24-Mar-2022|
|Date of Web Publication||12-Aug-2022|
Dr. Darshak Patel
Department of Cardiovascular and Thoracic Surgery, U. N. Mehta Institute of Cardiology and Research Center (Affiliated to B. J. Medical College), Ahmedabad, Gujarat
Source of Support: None, Conflict of Interest: None
Background: Off-pump coronary artery bypass (OPCABG) grafting has emerged as an effective alternative technique for allowing coronary revascularization without the use of cardiopulmonary bypass. OPCABG has been associated with decreased postoperative morbidity, shorter hospital stay, reduced cost, and reduced operative mortality in some studies.
Materials and Methods: A total of 190 patients who underwent isolated coronary artery bypass graft surgery were evaluated with the European System for Cardiac Operative Risk Evaluation (EuroSCORE) risk scoring system. Moreover, we also compared the discriminatory potentials between the EuroSCORE II with <5 and >5 scores.
Results: EuroSCORE high-risk patients showed higher rates of blood transfusion (66.9%), intraaortic balloon pump insertion (12.6%), atrial fibrillation (21%), and renal failure (46.8%). There was one mortality in each EuroSCORE group.
Conclusion: OPCABG can be accomplished safely in selected high-risk patients with acceptable morbidity and mortality without compromising complete revascularization. Severe renal failure needing dialysis, stroke, and deep sternal wound infection in the postoperative period carries high morbidity and mortality after OPCABG. There is no ideal risk prediction model for an individual patient but multidisciplinary approach and individual patient factors determine the operative risk.
Keywords: European system for cardiac operative risk evaluation II, left ventricular ejection fraction, off-pump coronary artery bypass
|How to cite this article:|
Patel D, Patel M, Meharwal Z S. Prospective analysis of early outcomes of off-pump coronary artery bypass in high-risk patients and role of EuroSCORE-II. Heart India 2022;10:68-73
|How to cite this URL:|
Patel D, Patel M, Meharwal Z S. Prospective analysis of early outcomes of off-pump coronary artery bypass in high-risk patients and role of EuroSCORE-II. Heart India [serial online] 2022 [cited 2023 Jun 2];10:68-73. Available from: https://www.heartindia.net/text.asp?2022/10/2/68/353730
| Introduction|| |
Off-pump coronary artery bypass (OPCABG) grafting has emerged as an effective alternative technique for allowing coronary revascularization without the use of cardiopulmonary bypass.,, OPCABG has been associated with decreased postoperative morbidity, shorter hospital stay, reduced cost, and reduced operative mortality in some studies.,,, Most of the previous studies have focused on low-risk or a mixed group of patients. However, OPCABG has its greatest benefit in high-risk patients. Today, increasing number of patients referred for CABG has more comorbidities making them high risk for operation.
The European System for Cardiac Operative Risk Evaluation (EuroSCORE) is a cardiac risk model for predicting mortality after cardiac surgery. It was launched in 1999 and revised in 2012 as EuroSCORE II. It has been widely used to predict operative mortality and as benchmark of results in hospitals.
| Materials and methods|| |
Study design and population
High-risk patients with Coronary Artery Disease (CAD) planned for CABG who gave informed written consent were included in the study. Patients were excluded if they had undergone CABG with other procedures or OPCABG converted to ONCABG (on-pump CABG).
Definition of high-risk patients
The patients who had one or more of the following features were considered high-risk for this study: EuroSCORE II ≥5, left main coronary artery critical (≥70%) stenosis, elderly patients (age ≥75 years), renal dysfunction (serum creatinine ≥2.0 mg/dl), previous history of stroke with or without residual neurological deficit, poor left ventricular ejection fraction (LVEF) (EF <35%), and redo CABG.
All the patients who were operated for OPCABG in the hospital and fulfilled the above mentioned criteria for high-risk patients were included as the study population. EuroSCORE-II was calculated for all patients using hospital-approved software.
Cohort was divided on the basis of EuroSCORE-II value for subgroup analysis of mortality as presented in [Table 1]:
|Table 1: Subgroups based on European system for cardiac operative risk evaluation II|
Click here to view
Sample size estimate
As per the previously published study, the sample size was calculated based on the following parameters:
- Mortality in the EuroSCORE <5 groups: Po ≤0.5%
- Mortality in the EuroSCORE ≥5 groups: P1 = 9%
- Ratio of patients in the EuroSCORE <5 groups versus the EuroSCORE ≥5 groups: m = 2
- α = 0.05
- β = 0.20
- Desired power = 0.80.
Based on the above parameters, the required sample size was n = 190. Estimated required sample size for 80% probability (power = 0.80) of finding a positive result with 95% accuracy (P = 0.05 i.e., significant) for mortality was n = 190.
After taking informed written consent from each patient, following data collection was done using the subject enrollment form.
Preoperative demographic and clinical parameters collected were age, gender, the New York Heart Association Class (NYHA), history of recent myocardial infarction (MI) (90 days) and stroke, body mass index (BMI) calculation, serum creatinine, and history of risk factors for CAD such as Hypertension (HT), diabetes, chronic obstructive pulmonary disease, smoking, hyperlipidemia, hypothyroidism, and family history of CAD.
All patients had preoperative echocardiography (ECG), chest X-ray, carotid and femoral arterial color Doppler screening. Rest and redistribution thallium scan was done in patients with severe LV dysfunction with LVEF <25% for viable and hibernating myocardium and prognosis estimation.
Intraoperative parameters measured were operation time, number of grafts, type of grafts used, need for intraaortic balloon pump (IABP) and inotropic and vasopressor support, incidence of intraoperative arrhythmia (ventricular and supraventricular), and number of blood products transfused.
Each patient had a radial arterial line and central venous line for monitoring of blood pressure and central venous pressure, respectively. Pulmonary artery catheterization (Swan-Ganz catheter) and transesophageal echocardiography were used in patients with severe left ventricular dysfunction, high-pulmonary artery pressure on transthoracic echocardiography, and recent MI. Cell saver was used in patients with preoperative low hemoglobin level and rare blood group. Grafts used were left internal mammary artery (LIMA), right internal mammary artery (RIMA), radial artery, and great saphenous vein. All patients had median sternotomy. OCTOPUS® (Medtronic) stabilizer and Starfish (Medtronic) apical suction device for cardiac positioning were used in all patients. Intracoronary shunts were used in all patients and coronary sling was used in some patients for shunt placement and to decrease the blood loss during distal anastomosis. Graft patency was checked in all patients with Doppler ultrasound.
Postoperative parameters and follow-up till discharge
Early postoperative parameters measured were need for re-exploration, inotropic and vasopressor support, IABP support, ST-T changes in ECG, cardiac enzymes (CPK-MB and TROPONIN I) after 6 h and 24 h, arrhythmia, duration on ventilator and re-intubation, stroke, mediastinal bleeding, and blood products requirement, duration of intensive care unit (ICU) stay, renal dysfunction, and need for dialysis.
Renal dysfunction was determined by the international Kidney Disease: Improving Global Outcomes (KDIGO) staging classification of acute kidney injury (AKI). AKI was defined as any of the following: increase in serum creatinine by ≥0.3 mg/dl within 48 h, or increase in serum creatinine to ≥1.5 times baseline, or urine volume ≤0.5 ml/kg/h for 6 h. Postoperative echocardiography was done in patients with raised cardiac enzymes (>10 times). Incidence of sternal wound infection (superficial and deep), duration of hospital stay, and mortality were measured till discharge of the patient.
Descriptive analysis was carried out. Categorical variables were presented as numbers (%). Continuous variables were presented as mean ± standard deviation or median with 25th–75th percentile as appropriate. Group-wise comparisons for categorical variables were performed using the Chi-square test or Fisher exact test, whichever was applicable. Group-wise comparisons for continuous variables were performed by Student's t-test. Data analysis was performed using IBM SPSS statistical software (IBM SPSS Statistics for Windows, Version 22.0. Armonk, NY: IBM Corp., USA).
| Results|| |
Study population characteristics
From May 2013 to April 2014, a total of 190 patients were enrolled in the study. The preoperative characteristics of the patients are provided in [Table 2].
Distribution of patients according to age is presented in [Figure 1].
The intraoperative data are explained in [Table 3].
Detailed lists of postoperative changes are provided in [Table 4].
Perioperative parameters are depicted in [Table 5].
Mortality in high-risk coronary artery bypass patients
Mortality was 1.1% in this study. [Table 6] provides information on mortality.
Subgroup analysis between the European system for cardiac operative risk evaluation groups for mortality
As mentioned in [Table 7], one patient with EuroSCORE <5 and one patient with EuroSCORE ≥5 died in this study.
| Discussion|| |
A total of 190 patients were enrolled in the present study. Twenty-two (11.6%) patients in the current study were considered elderly (age >75 years) as high-risk criterion for selection as shown in the previous study. Poor LVEF (EF <35%) was reported in 43.7% of patients in the present study. Five (2.6%) patients had severe MR. Severe MR in these patients was not surgically treated in this study. Postoperative echo in these patients revealed mild MR in four patients and moderate MR in one patient. Fifty-eight (30%) of patients in our study had critical left main coronary artery stenosis ≥70.
The mean number of grafts was 3 ± 0.8 in our study. Hence, the revascularization was complete in our study in contrast to the other studies which showed incomplete revascularization in OPCABG. Internal mammary artery (IMA) was used as graft in 123 (64.8%) patients. In 67 (35.3%) patients, IMA was not used as graft. The reasons for not using IMA were diffusely diseased LAD or critical left main stenosis requiring immediate revascularization or poor LIMA flow. The radial artery was used in patients with age <60 years and who had critical lesions in Obtuse Marginal (OM) or Right Coronary Artery (RCA) after negative Alan's test with pulse oximeter.
Perioperative IABP was used in 24 (12.6%) patients. Previously published studies have shown that perioperative IABP was used in 15% of patients. Thirteen patients had preoperative IABP before entering to the operation theater. The indications of preoperative IABP were cardiogenic shock following acute MI (<7 days) or critical left main coronary artery stenosis and triple vessel disease with unstable angina waiting for surgery etc., In 10 patients, IABP was inserted after induction or during grafting due to high PA pressures or hemodynamic instability due to low LVEF. Moreover, only one patient required IABP insertion in the postoperative period in ICU due to hemodynamic instability.
Forty-nine (25.8%) patients did not require any blood products transfusion during hospital stay leading to less morbidity which was reflected in relatively short median ICU and hospital stay in this high-risk cohort.
Twelve (6.3%) patients developed postoperative MI in our study which was lower compared to the study by Al-Ruzzeh et al. in which 9.4% of patients developed postoperative MI. Of these 12 patients, only four patients had regional wall motion abnormality and decreased LVEF on echocardiography. All these four patients showed ST-T changes in postoperative ECG as well. Four (2.1%) patients developed postoperative stroke. Of 21 patients who had previous history of stroke, 2 (9.5%) patients developed postoperative stroke.
Eighty-nine (46.8%) patients developed Stage 1 AKI. Of these 89 patients, 16 patients had preoperative. Serum creatinine ≥2.0. Raised serum creatinine in AKI was transient in most patients which reduced to basal level over 2–3 days. However, severe renal failure requiring hemodialysis developed in 4 (2.1%) patients. Of these four patients, two mortalities occurred. All four patients who developed severe renal failure requiring hemodialysis had preoperative serum creatinine <2.0. There was a high incidence of AKI in our study as compared to other studies in which AKI was in 40% cases because renal dysfunction in this study was determined by the international KDIGO staging classification of AKI.,
Two (1.1%) patients developed deep sternal wound infection. Previous studies have shown that 1.59% of patients developed deep sternal wound infection. In two patients who developed deep sternal wound infection, both patients required sternal rewiring due to sternal instability and in both cases, mortality occurred.
One hundred and thirty-one (68.9%) patients had EuroSCORE <5 and 59 (31.1%) patients had EuroSCORE ≥5. The lowest EuroSCORE was 0.55% and the highest EuroSCORE was 35.55% in our study with the mean EuroSCORE of 4.4% ± 4.2%. 2 (1.1%) mortalities occurred in our study, which was less compared to previously published studies which reported 3% and 3.3% mortality. There was one mortality in each EuroSCORE group. This shows poor calibration and discrimination of EUROSCORE as risk prediction model as shown in other studies., However, no risk model is ideal because of variation in demography and institutional practices. Moreover, no single risk factor by itself determines mortality.
Limitations of this study were a single-center study, no randomization for the selection of the study patients, and the sample size was relatively small. Furthermore, there was no follow-up of patients after discharge.
| Conclusion|| |
OPCABG can be accomplished safely in selected high-risk patients with acceptable morbidity and mortality without compromising complete revascularization. Severe renal failure needing dialysis, stroke, and deep sternal wound infection in the postoperative period carries high morbidity and mortality after OPCABG. There is no ideal risk prediction model for an individual patient but a multidisciplinary approach and individual patient factors determine the operative risk.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
Enrollment of the patients done after taking approval of institutional ethics committee.
Dr. Darshak Patel: This author helped in Concepts, Design, Literature search, Clinical studies, Experimental studies, Data analysis, Manuscript preparation, Manuscript review and finalize the study. Dr. Mrunal Patel: This author helped in Literature search, Experimental studies, Data analysis and in Manuscript preparation.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7]