Impact of lipid levels and high-intensity statins on vein graft patency after CABG: Midterm results of the ACTIVE trial

Medical Therapy After CABG: the Known Knowns, the Known Unknowns, and the Unknown Unknowns

PURPOSE

Medical therapies play a central role in secondary prevention after surgical revascularization. While coronary artery bypass grafting is the most definitive treatment for ischemic heart disease, progression of atherosclerotic disease in native coronary arteries and bypass grafts result in recurrent adverse ischemic events. The aim of this review is to summarize the recent evidence regarding current therapies in secondary prevention of adverse cardiovascular outcomes after CABG and review the existing recommendations as they pertain to the CABG subpopulations.

RECENT FINDINGS

There are many pharmacologic interventions recommended for secondary prevention in patients after coronary artery bypass grafting. Most of these recommendations are based on secondary outcomes from trials which include but did not focus on surgical patients as a cohort. Even those designed with CABG in mind lack the technical and demographic scope to provide universal recommendations for all CABG patients.

CONCLUSION

Recommendations for medical therapy after surgical revascularization are chiefly based on large-scale randomized controlled trials and meta-analyses. Much of what is known about medical management after surgical revascularization results from trials comparing surgical to non-surgical approaches and important characteristics of the operative patients are omitted. These omissions create a group of patients who are relatively heterogenous making solid recommendations elusive. While advances in pharmacologic therapies are clearly adding to the armamentarium of options for secondary prevention, knowing what patients benefit most from each therapeutic option remains challenging and a personalized approach is still required.

Adherence to secondary prevention recommendations after coronary artery bypass graft surgery

OBJECTIVE

This study was undertaken to assess and evaluate adherence to secondary prevention recommendations and risk factor modifications among a patient cohort at a single-tertiary centre in Ireland, following coronary artery bypass grafting (CABG).

METHODS

This is a retrospective observational study analysing patients who had CABG from 2015 to 2020, identified via the Adult Cardiac Surgery Database. Patients were asked a number of questions either over the phone or via postal survey, regarding blood pressure, cholesterol control, adherence to medication, attendance at cardiac-rehab and lifestyle factors. Any repeat interventions following CABG were noted.

RESULTS

A total of 540 patients were invited to take part in this study. One hundred seventy-three patients consented to participate, ranging from 47 to 86 years old. Postoperatively, 59% of participants attended cardiac rehab. 90.2% of patients report taking a statin, 91.3% report taking an antiplatelet, 77.4% report taking a β-blocker and 75.7% take an antihypertensive. 93.1% of patients questioned in this study reported full compliance with their daily medications. Sixteen patients continue to have hypertension despite their current regimen. Thirteen patients continue to have hypercholesterolemia despite their current prescription. 62.4% of participants have quit smoking with only 4.6% remaining current smokers. No patients required re-operation, and eight patients required stenting. Compliance with diet and exercise modifications was suboptimal.

CONCLUSION

In this patient population, adherence to medication and control of risk factors is acceptable. However, there is room for improvement in terms of attendance at cardiac rehab (59%) and maintenance of a healthy lifestyle post-CABG.

Effect of Perioperative Lipid Status on Clinical Outcomes after Cardiac Surgery

Patients undergoing cardiac surgery are at increased cardiovascular risk, which includes altered lipid status. However, data on the effect of cardiac surgery and cardiopulmonary bypass (CPB) on plasma levels of key lipids are scarce. We investigated potential effects of CPB on plasma lipid levels and associations with early postoperative clinical outcomes. This is a prospective bio-bank study of patients undergoing elective cardiac surgery at our center January to December 2019. The follow-up period was 1 year after surgery. Blood sampling was performed before induction of general anesthesia, upon weaning from cardiopulmonary bypass (CPB), and on the first day after surgery. Clinical end points included the incidence of postoperative stroke, myocardial infarction, and death of any cause at 30 days after surgery as well as 1-year all-cause mortality. A total of 192 cardiac surgery patients (75% male, median age 67.0 years (interquartile range 60.0-73.0), median BMI 26.1 kg/m² (23.7-30.4)) were included. A significant intraoperative decrease in plasma levels compared with preoperative levels (all p < 0.0001) was observed for total cholesterol (TC) (Cliff's delta d: 0.75 (0.68-0.82; 95% CI)), LDL-Cholesterol (LDL-C) (d: 0.66 (0.57-0.73)) and HDL-Cholesterol (HDL-C) (d: 0.72 (0.64-0.79)). At 24h after surgery, the plasma levels of LDL-C (d: 0.73 (0.650.79)) and TC (d: 0.77 (0.69-0.82)) continued to decrease compared to preoperative levels, while the plasma levels of HDL-C (d: 0.46 (0.36-0.55)) and TG (d: 0.40 (0.29-0.50)) rebounded, but all remained below the preoperative levels (p < 0.001). Mortality at 30 days was 1.0% (N = 2/192), and 1-year mortality was 3.8% (N = 7/186). Postoperative myocardial infarction occurred in 3.1% of patients (N = 6/192) and postoperative stroke in 5.8% (N = 11/190). Adjusting for age, sex, BMI, and statin therapy, we noted a protective effect of postoperative occurrence of stroke for pre-to-post-operative changes in TC (adjusted odds ratio (OR) 0.29 (0.07-0.90), p = 0.047), in LDL-C (aOR 0.19 (0.03-0.88), p = 0.045), and in HDL-C (aOR 0.01 (0.00-0.78), p = 0.039). No associations were observed between lipid levels and 1-year mortality. In conclusion, cardiac surgery induces a significant sudden drop in levels of key plasma lipids. This effect was pronounced during the operation, and levels remained significantly lowered at 24 h after surgery. The intraoperative drops in LDL-C, TC, and HDL-C were associated with a protective effect against occurrence of postoperative stroke in adjusted models. We demonstrate that the changes in key plasma lipid levels during surgery are strongly correlated, which makes attributing the impact of each lipid to the clinical end points, such as postoperative stroke, a challenging task. Large-scale analyses should investigate additional clinical outcome measures.