Effect of Diabetes Mellitus on Long-Term Outcomes of Surgical Revascularization in Patients with Ischemic Heart Failure: A Propensity Score-Matching Study
Ischemic heart disease (IHD), diabetes mellitus (DM), and heart failure (HF) are significant public health concerns worldwide. Among these, IHD is the leading cause of HF, while DM plays a critical role in the occurrence, development, and long-term outcomes of HF caused by IHD. Coronary artery bypass grafting (CABG) is widely accepted as the standard treatment for IHD. For patients with ischemic heart failure (IHF), which refers to HF caused by IHD, CABG demonstrates better outcomes compared to percutaneous intervention and oral medication therapy. Current guidelines recommend CABG as the first-line treatment for IHF patients. However, the impact of DM on the long-term outcomes of CABG in IHF patients remains controversial. This study aims to evaluate the effect of DM on the long-term outcomes of IHF patients undergoing CABG, providing contemporary evidence for clinical practice.
The study is a single-center retrospective analysis of IHF patients who underwent CABG at the PLA General Hospital from January 2007 to December 2017. A total of 439 patients were included, with a mean follow-up period of 73 months. Patients were divided into two groups based on the presence or absence of DM. The primary endpoint was all-cause death, and the secondary endpoint was a composite of all-cause death, stroke, recurrent myocardial infarction (MI), and revascularization. Propensity score matching was used to balance baseline characteristics between the DM and non-DM groups, ensuring a fair comparison.
Before matching, the DM group consisted of 183 patients, while the non-DM group had 256 patients. After propensity score matching, 173 pairs of patients were selected, ensuring comparable baseline characteristics. The matching criteria included pre-operative echocardiographic parameters such as left ventricular ejection fraction (LVEF) and left ventricular end-diastolic dimension (LVEDD), as well as risk factors from the Euroscore, such as age and sex. The baseline characteristics of the patients, including demographic data, comorbidities, and pre-operative status, were thoroughly analyzed and presented in Table 1.
All CABG procedures were performed under general anesthesia using a median sternotomy approach, with or without cardiopulmonary bypass, depending on the patient’s condition and surgeon’s preference. The left internal mammary artery (LIMA) was preferentially grafted to the left anterior descending artery, while the great saphenous vein was used for other lesions. Post-operatively, all patients received standard dual antiplatelet therapy, consisting of aspirin and clopidogrel, for at least one year, followed by either aspirin or clopidogrel alone. Additionally, patients were treated with statins, angiotensin-converting enzyme inhibitors, and beta-blockers as needed. Patients in the DM group received oral hypoglycemic agents or insulin to control blood glucose levels, aiming for a target of 6 mmol/L before surgery.
The primary outcome of the study was all-cause mortality, while the secondary outcome was the incidence of major adverse cardiovascular and cerebrovascular events (MACCE), which included all-cause death, stroke, MI, and revascularization. The results showed no significant difference in all-cause mortality between the DM and non-DM groups (5.8% vs. 4.1%, P = 0.216). However, the incidence of MACCE was significantly higher in the DM group compared to the non-DM group (10.4% vs. 8.1%, P = 0.023). This indicates that while DM does not significantly affect long-term survival in IHF patients undergoing CABG, it does increase the risk of adverse cardiovascular and cerebrovascular events.
Kaplan-Meier analysis was used to assess the cumulative incidence of primary and secondary outcomes. The analysis revealed no significant difference in the incidence of all-cause death between the DM and non-DM groups (Figure 2A). However, the DM group had a significantly higher risk of composite endpoint events (Figure 1). Cox regression analysis further confirmed that the non-DM group had a lower risk of MACCE compared to the DM group (hazard ratio = 0.605; 95% CI 0.39 to 0.94, P = 0.024). There were no significant differences in the individual components of the composite endpoint, including stroke, MI, and revascularization, between the two groups (Figures 2B, 2C, and 2D).
The study also examined perioperative outcomes, including in-hospital mortality, severe ventricular arrhythmia, post-operative renal failure, low cardiac output, and respiratory insufficiency. No significant differences were observed between the DM and non-DM groups in these perioperative adverse events (Table 2). This suggests that DM does not significantly impact the immediate post-operative outcomes of CABG in IHF patients.
The findings of this study are consistent with previous research indicating that DM is a high-risk factor for adverse cardiovascular events in patients undergoing CABG. However, the study also highlights that advancements in treatment strategies and glucose control have improved the long-term survival of DM patients with cardiovascular disease. The use of propensity score matching in this study helps to eliminate baseline characteristic biases, providing more robust evidence on the impact of DM on long-term outcomes in IHF patients undergoing CABG.
DM affects the outcomes of CABG through both anatomical and metabolic mechanisms. Anatomically, DM accelerates atherosclerosis and alters the microvascular structure, leading to more severe and diffuse coronary lesions. Metabolically, long-term abnormal glucose metabolism causes myocardial remodeling, hypertrophy, and fibrosis, contributing to diabetic cardiomyopathy (DCM). DCM is an independent risk factor for HF, further complicating the management of IHF patients with DM. Despite these challenges, CABG remains a standard treatment for IHF patients with DM, offering relatively good clinical benefits when combined with meticulous pre-operative evaluation and perioperative management.
In conclusion, DM negatively impacts the long-term outcomes of IHF patients undergoing CABG by significantly increasing the overall incidence of MACCE. However, there is no significant difference in long-term survival between DM and non-DM patients. These findings underscore the importance of comprehensive management strategies for IHF patients with DM undergoing CABG, focusing on both glucose control and cardiovascular risk reduction. Future large-scale, multicenter studies or randomized controlled trials are needed to further evaluate the effect of DM on the long-term outcomes of CABG in IHF patients.
doi.org/10.1097/CM9.0000000000001421
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