Coronary Artery Bypass Grafting: A Comparative Exercise between Patients from the BYPASS Registry and Patients from a University Hospital

Introduction The coronary artery bypass grafting (CABG) data provided by the Brazilian Registry of Cardiovascular Surgeries in Adults (BYPASS) Registry is a Brazilian reality. Objective To carry out a comparative exercise between the BYPASS Registry published data and data from patients operated on in a randomly chosen period (2013-2015) at Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo (HCFMRP-USP). Methods This is a retrospective study reviewing 173 electronic medical records of CABG patients from the HCFMRP-USP. These data were compared with the BYPASS Registry published data. Chi-square test was used to verify the changes within the prevalence of adequate/inadequate biochemical tests before and after surgery. The sample was divided into groups consistent with cardiopulmonary bypass (CPB) time (CPB ≤ 120 minutes and CPB > 120 minutes). For the complications, prevalence by the chi-square test was adopted. Significant P-values are < 0.05. Results The comparative operative data of the BYPASS Registry and the HCFMRP-USP patients were quite similar, except for the isolate use of only arterial grafts, which was more frequent on HCFMRP-USP patients (30.8% vs. 15.9%), and the use of radial artery, also more frequent on HCFMRP-USP patients (48.8% vs. 1.1%) Conclusion The comparative study suggested that the BYPASS Registry should be a reference for CABG quality control.


INTRODUCTION
Worldwide, cardiovascular disease remains the leading cause of death for both women and men. Regulatory agencies and public funding agencies have put forth recommendations to improve inclusivity and diversity in clinical trials; however, only limited progress has been made. According to Khan & Mitchell (2021) [1] , the homogeneity of cardiovascular clinical trial populations limits the generalizability of results and compounds health inequities faced by women, older adults, and people of color. This article highlights the importance of diversity in clinical trial populations and describes multifaceted interventions that might help to close the diversity gap in trial enrolment. Although it has high international prestige, Brazilian cardiac surgery failed to carry out a large "trial" on coronary artery bypass grafting (CABG) [2] . The Brazilian Registry of Cardiovascular Surgeries in Adults (BYPASS) Registry project is fulfilling the purpose of portraying cardiovascular surgery in Brazil [3,4] and should be a crucial reference for indications and comparisons of therapeutic procedures. Therefore, this presentation aimed to carry out a comparative exercise between BYPASS Registry data and data from patients operated on in a randomly chosen period (2013)(2014)(2015) at Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo (HCFMRP-USP). This presentation intends to be a kind of test incentive and consequently reinforces the BYPASS Registry as a pivotal Brazilian cardiac surgery database.

Patients
The , and ischemia) also were collected because they got to use vasoactive drugs after CPB. Postoperative parameters were also evaluated, as the necessity for blood transfusion and intra-aortic balloon use, the prevalence of deaths and causes, and the need for reintervention and their reasons.

Statistical Analysis
Continuous variables were presented as mean ± standard deviation and categorical variables as percentages. The chi-square test was used to verify the changes within the prevalence of adequate/inadequate biochemical tests before and after surgery. The sample was divided into groups consistent with CPB time (CPB ≤ 120 minutes and CPB > 120 minutes) and mechanical ventilation (MV) time (MV ≤ 2 days and MV > 2 days). For the complications, prevalence by the chi-square test was adopted. The collected data was analyzed using the IBM Corp. Released 2011, IBM SPSS Statistics for Windows, version 20.0, Armonk, NY: IBM Corp. Significant P-values are < 0.05.

Patients Operated at HCFMRP-USP
1) The prevalence of patients undergoing CABG was higher in males; 2) most had hypertension, severe coronary lesion, dyslipidemia, and were smokers; 3) the foremost commonly used medications were acetylsalicylic acid (ASA), beta-blockers, and simvastatin; 4) there was evidence of renal and hepatic dysfunction; 5) most of the surgical reinterventions were bleeding, stroke, and acute myocardial infarction (AMI). Numbers are presented in Table 1

Patients From the Bypass Registry
Data of the BYPASS Registry group were obtained from the BJCVS.  (Tables 3 and 4). Concerning comparative postoperative data, the BYPASS Registry patients presented low reoperation rate (2.3 vs. 8%), less renal failure (4.8 vs. 24.4%), and low mortality (2.8 vs. 7.3%); the HCFMRP-USP patients presented fewer arrhythmias (4.6 vs. 14.1%) Finally, the other postoperative differences between BYPASS Registry and HCFMRP-USP patients are shown on Table 5.

DISCUSSION
The BYPASS Registry database is an important reference for indications and comparisons of therapeutic procedures, as well as to propose subsequent models to improve patient safety and the quality of surgical practice in the country [3][4][5] .
Concerning the most important differences, the BYPASS Registry patients were older, and presented more heart failure. It is notable the AMI difference, which was more prevalent in the BYPASS Registry (41.1%) than in the HCFMRP-USP (3.4%) patients. Also, it is notable that operative mortality in the BYPASS Registry (2.8%) was lowest than HCFMRP-USP 30-day mortality (7.5%). The postoperative hospital outcomes were analyzed. Patients referred to CABG in Brazil are predominantly male (71%), with prior myocardial infarction in 41.1% of cases, diabetes in 42.5%, and ejection fraction < 40% and > 9.7%. The Heart Team surgery decided 32.9% of the surgical indications. Most of the patients underwent CPB (87%), and cardioplegia was the strategy of myocardial protection chosen in 95.2% of the cases. The left internal thoracic artery was used as a graft in 91% of the cases, the right internal thoracic artery in 5.6%, and the radial artery in 1.1%. The saphenous vein graft was used in 84.1% of the patients, being the only graft employed in 7.7% of the patients. The median number of coronary vessels treated was three.
Operative mortality was 2.8%, and the incidence of cerebrovascular accident was 1.2%. The HCFMRP-USP postoperative 30-day hospital mortality rate value is higher than the BYPASS Registry value, but it is an acceptable value, according to the present literature, even though the study was done in a university hospital, where the work involves the participation of academics and residents, as well as teachers and bosses.   surgery, and 16.5% for "complex" operations (e.g., thoracic aorta and combined procedures). The investigators also found that hospitals with annual volumes of less than 341 operations had higher mortality. Unfortunately, it was not possible to define this parameter in the present study, since a group of patients were operated on in a single hospital (HCFMRP-USP) and BYPASS Registry patients were operated on in several hospitals. But the anecdotal observation remains that mortality is higher in services that operate less. It would still be necessary to consider a bias created by the possibility of centralizing surgeries to correct complex heart diseases for specialized hospitals with fewer surgeries.
According to Cram (2005) [6] and Hwang (2007) [7] , it is supposed that cardiac specialty hospitals assert better patient outcomes and efficiency, whereas general hospitals attract healthier patients. Favorable patient selection may occur at cardiac specialty hospitals. Although healthier patients are comparably across types of hospitals, patients with greater comorbid disease seem to experience worse 30-day post-discharge mortality at specialty hospitals [7] . According to Anglemyer et al. (2014) [8] , researchers and organizations often use evidence from randomized controlled trials to determine the efficacy of a treatment or intervention under ideal conditions. Studies of observational designs are often used to measure the  effectiveness of an intervention in "real world" scenarios. Also, according to Black (1996) [9] , when trials cannot be conducted, well designed observational methods offer an alternative to doing nothing. They also offer the opportunity to establish high external validity, something that is difficult to achieve in randomized trials. Instead of advocates of each approach criticizing the other method, everyone should pursue for greater rigor in the in the execution of research, regardless of the method used.

Limitations
The BJCVS announced the fully operational BYPASS Registry in 2016, and the data inclusion has exceeded 1,500 patients in the first nine months of operation. The establishment of the BYPASS Registry sets a long-standing need for fundamental understanding of the real figures pertaining to the cardiovascular surgery practice, resulting in developing strategies for improvements in quality and excellence, the main motivation of the present investigation [3][4][5] .

CONCLUSION
In conclusion, we emphasize three main points: • CABG data in Brazil provided by the BYPASS Registry analysis are representative of our national reality and practice. This database constitutes an important reference for indications and comparisons of therapeutic procedures, as well as to propose subsequent models to improve patient safety and the quality of surgical practice in the country. • The comparative operative data of the BYPASS Registry and the HCFMRP-USP patients were quite similar, except for the use of only arterial grafts, which were more frequent on the