Short Term Prognosis in Patients with Diabetes Mellitus after Coronary Revascularization

In the modern world, diabetes presents enormous health and financial difficulties, particularly in underdeveloped nations. In 2021, there were approximately 53.7 billion persons worldwide had diabetes particularly with India having the second-highest number of such individuals (7.42 billion).^1,2 It affects quality of life and the development of a wide spectrum of complications, including cardiovascular risk. Compared to people without diabetes, cardiovascular mortality rate is twice as high in patients with diabetes.^3,4 The pathological profile of coronary lesions in diabetic individuals with CVD is more complex and is characterized by calcified, diffuse, multivessel disease and a greater burden of atherosclerotic plaques.⁵ As a result, these patients require revascularization and assessment of their coronary lesions, in addition to obtaining the finest medical care possible.⁶

Clinicians have become increasingly concerned about the epidemiological transition, rising prevalence of diabetes as a key risk factor for CAD, and choice of treatment plan. Revascularization using two techniques CABG Coronary Artery Bypass Graft (CABG) and Percutaneous Coronary Intervention (PCI), has generated a great deal of interest in these treatment options as possible measures for this high-risk patient population. This is because patients with diabetes account for one-fourth of the 1.5 million revascularizations performed each year.^7,8 Following the advent of new oral antiplatelet medications and drug-eluting stents (DES), there was a significant decrease in the clinical results of the two techniques involved. ^9,10

The optimal revascularization approach for individuals with diabetes and CVD is still unknown, despite the introduction of DES and a decrease in repeat revascularization and in-stent restenosis compared with bare-metal stents.¹¹ The present study was carried out in a South Indian tertiary care hospital to compare the short-term clinical outcomes following revascularization in a cohort of patients with and without diabetes following percutaneous coronary intervention or coronary artery bypass graft.

Patients with CVD who were hospitalized for revascularization at the Cardiology Department of Kovai Medical Center and Hospital (KMCH), Coimbatore, were included in this prospective study. The study received approval from Institutional Ethical Committee (reference number EC/AP/907/05/2022) of Kovai Medical Centre and Hospital for a period of five months. Informed consent from patients was obtained during study. Patients over 18 years old who had successful surgery between December 2022 and June 2023 were included in the study. Patients who had multiple surgical procedure (undergone previous cardiac surgeries, CABG with valvular intervention, peripheral arterial bypass grafting) were excluded. The baseline demographics, in-hospital outcomes, and clinical and procedural characteristics were all gathered prospectively from hospital records. Based on the revascularization method and the presence or absence of diabetes mellitus, each cohort was split into two groups and a subgroup. The patients within diabetes group included those who had confirmed diagnosis of diabetes and were on hypoglycemic treatments like insulin or oral anti diabetic medications. Patients were followed-up for the first 30 days since surgery, and major clinical outcomes were noted in both groups.

IBM SSPS version 22 was used to conduct statistical analysis of the data. This study presented a distribution that based on the revascularization technique in the diabetic and non-diabetic cohorts. Mean and Standard Deviation (SD) were used to describe the data for continuous variables. The percentages were calculated using the entire set of variables. The student’s t-test was used to analyze baseline characteristics between different groups for continuous variables, while the chi-squared test method was used for discrete variables. p values were considered two-sided, and statistical significance was set at p<0.05. Kaplan-Meier survival chart was plotted using log rank (Mantel-Cox) test. Mortality was considered as event occurred and survival time was referred as days elapsed. Graphical representation was used for the visual comprehension of the data collected.

We enrolled two hundred twenty-eight patients who underwent successful revascularization in the study center, but only two hundred and three patients who satisfied our criteria were included. Fourteen patients were lost on the follow-up. In total, one hundred eight-nine people were chosen for the study (Figure 1).

Figure 1:
Sequence chart displaying selection procedure.

Out of the total participants, 53.9% had diabetes mellitus, one hundred patients (52.9%) (diabetic: 60; non-diabetic: 40) were in the CABG arm and 89 patients (47.1%) (diabetic: 42; non-diabetic: 47) were in the PCI arm as shown in Figure 2.

Figure 2:
Bar chart displaying cohort layout under study.

Majority of patients were males. The subjects had a mean BMI of 25.2 kg/m² (Table 1) with a mean age of 60.5 years. In the CABG group, the smoking and alcohol consumption rates in the diabetes group were 13.3% and 11.7% respectively. Except for the history of hypertension, history of renal failure, urea level, and RBS level between the diabetic and non-diabetic groups, no statistically significant differences were observed. 50% of the study population had Myocardial Infarction (MI) history and 6.7% had a history of CVA. In the PCI arm, 46% of the study population had history of MI and 7.2% had a history of CVA (Table 1).

Categorization of the diabetes and non-diabetic group was performed based on hypoglycemia treatment. The mean blood glucose levels were calculated before and after surgery. HBA1C was estimated 7.9 in the CABG and 8.1 in the PCI arm. Compared with insulin treatment, OHA is preferred (Table 2).

Nearly all patients in the CABG arm, those with and without diabetes underwent off-pump surgery. Patients with diabetes received four grafts on average (46.67%), compared to three (45%) in the non-diabetic group. In the CABG group, triple-vessel disease was discovered to be significant in both diabetic and non-diabetic individuals (Table 3).

In the PCI arm, 82% of patients with diabetes received stents compared to 79% of those without diabetes. In the PCI arm, both the diabetic and non-diabetic patients had single-vessel disease. In the PCI research cohort, hospital stays were of shorter periods (Table 4) compared to CABG.

After a 30-day follow-up period following surgery in patients after PCI and CABG, analysis of Kaplan-Meier survival curves (Figure 3) showed that both the patients with and without DM had higher and similar survival rates with a log-rank p-value of 0.99

Figure 3:
Probability plot of Kaplan-Meier survival estimates for CABG and PCI.

Diabetes is considered as an independent risk factor for cardiovascular disorders. In those with diabetes mellitus, 80% of unexpected fatalities are mostly due to arteriosclerosis. Based on the several studies carried out, CABG was preferred for adverse CAD, but PCI was chosen for high operational risk factors such as diabetes mellitus, advanced age, and severe comorbidities.¹² When illness progression is rapid and wider, CABG is the preferred choice of therapy, especially for those with diabetes.¹³ The most current revascularization recommendations advocate CABG for subgroups such as diabetics with high SYNTAX score and Multivessel Disease (MVD). However, an increased proportion of patients are at a high surgical risk due to substantial comorbidities, advanced age, and poor left ventricular ejection fraction.¹⁴ We observed an increase in high-risk PCI (Percutaneous Coronary procedures) in our study group. Presence of severe comorbidities, diabetes mellitus and the anatomical severity of CVD should be among the key considerations when choosing the unique therapeutic procedures with a balanced treatment procedure, as suggested in the Heart Team study for both CABG and PCI revascularization techniques.¹⁵

In line with the findings of a research by Draznin et al., our study group had a higher percentage of males in the categories of diabetes and non-diabetes.¹⁶ We found a significant difference in urea, salt, history of hypertension, and random blood sugar levels between the diabetic and non-diabetic groups. In comparison to the non-diabetic group, the results were higher in the diabetes group, our study aligned with the outcomes of diabetes mellitus after coronary artery bypass surgery in a study conducted at Urmia.¹⁷

According to our analysis, there was no significant difference between the PCI and CABG groups in terms of prior MI, CVA, cardiac surgery or COPD. However, it was found that a history of MI, CVA, and prior cardiac surgery was significant and more common in individuals with diabetes, but a history of COPD was not significant and was more common in non-diabetics. According to a research conducted by Estrada et al. carried out to analyse the relationship between perioperative hyperglycemia and CABG, the choice of drugs for diabetes and non-diabetes groups, it was more likely for diabetes.¹⁸ According to the Kubal research, renal failure and diabetes are significantly correlated, which is consistent with our findings.¹⁹ Hemoglobin, potassium, and creatinine levels were found to be insignificant in our investigation, which was consistent with the results of the earlier study, while BMI was not found to be relevant, in contrast to the study by Wahid et al.²⁰ Due to the substantial operational risk involved in cardiac surgery, the number of people with CVD and DM in high-risk cohorts is increasing and many of them typically have distinct grounds for PCI. Arrhythmia, re-exploration for bleeding, stroke after revascularization, Pulmonary Embolism (PE), perioperative mortality, neurological (strokes and ischemic attacks) within-discharge mortality, and postoperative mortality within 30 days of follow-up were all analyzed as clinical outcomes. Between the DM and non-DM cohorts, we did not discover any statistically significant differences. High-risk DM patients who had PCI did not experience a noticeably higher in-hospital MACCE rate (Major Adverse Cardiac and Cerebrovascular Events) or an obvious change in one-month survival.

The study possesses certain limitations. The investigation was conducted using a small cohort from a single tertiary care center in South India hence limiting the possibility of extrapolating results and establishing causality to overall population.

To sum up, diabetes has little influence on adverse clinical outcomes or immediate side effects in our participants who had coronary revascularization. It was also observed that additional independent risk variables, such as urea, salt levels, and hypertension, need to be considered even though diabetes is often regarded as a major risk factor for coronary disease. To identify delayed complications in diabetic patients following revascularization, a bigger prospective randomized controlled multicenter trial with long-term follow-up data is needed.

The authors express heartfelt gratitude towards Kovai Medical Center and Hospital (KMCH), for providing all the facilities for completion of research.