Reducing Low-Density Lipoprotein Cholesterol After Myocardial Infarction in Older Individuals, Levels Versus Change: Can Observational Studies Answer the Questions?

Low-density lipoprotein cholesterol in oldest old with acute myocardial infarction: Is lower the better?

BACKGROUND

the relationship between low-density lipoprotein cholesterol (LDL-C) and adverse outcomes among the older people remains controversial.

OBJECTIVE

to further clarify the association between admission LDL-C levels and cardiovascular mortality (CVM) among oldest old individuals (≥80 years) with acute myocardial infarction (AMI).

DESIGN

a prospective cohort study.

SETTING

two-centre.

SUBJECTS

a consecutive sample of 1,224 oldest old individuals with AMI admitted to Beijing FuWai and Shenzhen FuWai hospitals.

METHODS

all individuals were subdivided according to baseline LDL-C levels (<1.8, 1.8-2.6 and ≥ 2.6 mmol/l) and further stratified by high-sensitivity C-reactive protein (hsCRP) concentrations (<10 and ≥10 mg/l). The primary outcome was CVM. The time from admission to the occurrence of CVM or the last follow-up was analysed in Kaplan-Meier and Cox analyses.

RESULTS

the median age of the overall population was 82 years. During an average of 24.5 months' follow-up, 299 cardiovascular deaths occurred. Kaplan-Meier analysis showed that LDL-C < 1.8 mmol/l group had the highest CVM among oldest old individuals with AMI. Multivariate Cox regression analysis further revealed that compared with those with LDL-C levels <1.8 mmol/l, subjects with LDL-C levels ≥2.6 mmol/l (hazard ratio: 0.67, 95% confidence interval: 0.46-0.98) had significantly lower risk of CVM, especially in those with high hsCRP levels. Moreover, when categorising according to LDL-C and hsCRP together, data showed that individuals with low LDL-C and high hsCRP levels had the highest CVM.

CONCLUSIONS

LDL-C < 1.8 mmol/l was associated with a high CVM after AMI in oldest old individuals, especially when combined with high hsCRP levels, which may need to be confirmed by randomised controlled trials.