Attainment of Lipid Targets Following Coronary Artery Bypass Graft Surgery: Can We Do Better?

Intensive Lipid-Lowering Therapy as per the Latest Dyslipidemia Management Guideline in Predicting Favorable Long-Term Clinical Outcomes in Patients Undergoing Coronary Artery Bypass Grafting: A Retrospective Cohort Study

Background There are limited data on low-density lipoprotein cholesterol (LDL-C) goal achievement per the 2019 European Society of Cardiology/European Atherosclerosis Society dyslipidemia management guidelines and its impact on long-term outcomes in patients undergoing coronary artery bypass grafting (CABG). We investigated the association between LDL-C levels attained 1 year after CABG and the long-term outcomes. Methods and Results A total of 2072 patients diagnosed with multivessel coronary artery disease and undergoing CABG between 2011 and 2020 were included. Patients were categorized by lipid levels at 1 year after CABG, and the occurrence of major adverse cardiovascular and cerebrovascular events (MACCEs) was evaluated. The goal of LDL-C <1.40 mmol/L was attained in only 310 patients (14.9%). During a mean follow-up of 4.2 years after the index 1-year assessment, 25.0% of the patients experienced MACCEs. Multivariable-adjusted hazard ratios (95% CIs) for MACCEs, cardiac death, nonfatal myocardial infarction, nonfatal stroke, revascularization, and cardiac rehospitalization were 1.94 (1.41-2.67), 2.27 (1.29-3.99), 2.45 (1.55-3.88), 1.17 (0.63-2.21), 2.47 (1.31-4.66), and 1.87 (1.19-2.95), respectively, in patients with LDL-C ≥2.60 mmol/L, compared with patients with LDL-C <1.40 mmol/L. The LDL-C levels at 1-year post-CABG were independently associated with long-term MACCEs. Conclusions This retrospective analysis demonstrates that lipid goals are not attained in the vast majority of patients at 1 year after CABG, which is independently associated with the increased risk of long-term MACCEs. Further prospective, multicenter studies are warranted to validate if intensive lipid management could improve the outcomes of patients undergoing CABG.

Are Only p-Values Less Than 0.05 Significant? A p-Value Greater Than 0.05 Is Also Significant!

Statistical hypothesis testing compares the significance probability value and the significance level value to determine whether or not to reject the null hypothesis. This concludes "significant or not significant." However, since this process is a process of statistical hypothesis testing, the conclusion of "statistically significant or not statistically significant" is more appropriate than the conclusion of "significant or not significant." Also, in many studies, the significance level is set to 0.05 to compare with the significance probability value, p-value. If the p-value is less than 0.05, it is judged as "significant," and if the p-value is greater than 0.05, it is judged as "not significant." However, since the significance probability is a value set by the researcher according to the circumstances of each study, it does not necessarily have to be 0.05. In a statistical hypothesis test, the conclusion depends on the setting of the significance level value, so the researcher must carefully set the significance level value. In this study, the stages of statistical hypothesis testing were examined in detail, and the exact conclusions accordingly and the contents that should be considered carefully when interpreting them were mentioned with emphasis on statistical hypothesis testing and significance level. In 11 original articles published in the Journal of Lipid and Atherosclerosis in 2022, the interpretation of hypothesis testing and the contents of the described conclusions were reviewed from the perspective of statistical hypothesis testing and significance level, and the content that I would like to be supplemented was mentioned.

Impact of low-density lipoprotein cholesterol and lipoprotein(a) on mid-term clinical outcomes following coronary artery bypass grafting: A secondary analysis of the DACAB trial

Purpose

The objective was to evaluate the influence of low-density lipoprotein cholesterol (LDL-C) and lipoprotein(a) [Lp(a)] on clinical outcomes in patients undergoing coronary artery bypass grafting (CABG).

Methods

This is a secondary analysis of a 5-year follow-up of the DACAB trial (NCT02201771), in which 500 patients who underwent primary isolated CABG were randomized to three-antiplatelet therapy for 1 year after surgery. Of them, 459 patients were recruited in this secondary analysis. Baseline LDL-C and Lp(a) levels were collected, and repeated measurement of LDL-C levels during the follow-up were recorded. Cut-off values for LDL-C were set at 1.8 and 2.6 mmol/L; thus, the patients were stratified into LDL-C <1.8, 1.8-<2.6, and ≥2.6 mmol/L subgroups. Cut-off value for Lp(a) was 30 mg/dL; thus, the patients were divided into Lp(a) <30 and ≥30 mg/dL subgroups. The primary outcome was 4-point major adverse cardiovascular events (MACE-4), a composite of all-cause death, myocardial infarction, stroke, and repeated revascularization. Median follow-up time was 5.2 (interquartile range, 4.2-6.1) years.

Results

During the follow-up, 129 (28.1%) patients achieved the attainment of LDL-C <1.8 mmol/L, 186 (40.5%) achieved LDL-C 1.8-<2.6 mmol/L, and 144 (31.4%) remained LDL-C ≥2.6 mmol/L. Compared with the postoperative LDL-C <1.8 mmol/L group, the risk of MACE-4 was significantly higher in the LDL-C 1.8-<2.6 mmol/L group [adjusted hazard ratio (aHR) = 1.92, 95% CI, 1.12-3.29; P = 0.019] and LDL-C ≥2.6 mmol/L group (aHR = 3.90, 95% CI, 2.29-6.64; P < 0.001). Baseline Lp(a) ≥30 mg/dL was identified in 131 (28.5%) patients and was associated with an increased risk of MACE-4 (aHR = 1.52, 95% CI, 1.06-2.18; P = 0.022).

Conclusions

For CABG patients, exposure to increased levels of postoperative LDL-C or baseline Lp(a) was associated with worse mid-term clinical outcomes. Our findings suggested the necessity of achieving LDL-C target and potential benefit of adding Lp(a) targeted lipid-lowering therapy in CABG population.