Low serum cholesterol. Hazardous to health?

High levels of C-reactive protein with low total cholesterol concentrations additively predict all-cause mortality in patients with coronary artery disease

BACKGROUND

This study aimed to investigate independent and additive predictive effects of raised C-reactive protein (CRP) levels and decreased total cholesterol levels on mortality in patients with chronic coronary artery disease (CAD). Low total cholesterol (TC) levels are associated with worsened survival in chronic and acute diseases. Elevated CRP level is an important predictor of vascular events and mortality in patients with CAD. Potential inhibition of immune activation by circulating lipoproteins could be a link between cholesterol and inflammatory markers.

MATERIALS AND METHODS

A group of 387 patients (median age 59 years) with CAD and with or without severe heart failure (HF) were followed for a median of 5.06 years. Serum total cholesterol and CRP concentrations were measured at enrollment.

RESULTS

The relationship between lipoproteins, CRP and survival was explored. High CRP concentrations were in significant association with severity of HF and predicted worsened survival in patients with CAD (hazard ratio 5.214, 95% CI 1.762-15.427). The association between CRP levels and mortality was independent of potential confounding factors such as age, body-mass index, severity of HF, smoking habits, hypertension and TC levels. The prediction of mortality by low TC levels was significant (hazard ratio 2.932, 95% CI 1.021-8.422). Furthermore, patients with increased CRP and decreased TC (additive predictive effect) phenotype had 11.714-times higher risk (95% CI 2.619-52.385) of being nonsurvivors than patients with low CRP/high TC.

CONCLUSIONS

High CRP levels and low TC concentrations are independent and additive predictors of mortality in patients with CAD. Our data indicate that joint analysis of circulating lipoproteins and inflammatory biomarkers may improve prediction of survival in patients with CAD.

Low serum total cholesterol is associated with marked increase in mortality in advanced heart failure

BACKGROUND

Although hypercholesterolemia is a well-defined risk factor for morbidity and mortality in coronary artery disease, the relationship between cholesterol and heart failure (HF) has rarely been investigated.

METHODS

Cholesterol and lipoproteins were measured in 1,134 patients with advanced HF who presented to a single center for HF management and transplant evaluation. Patients were stratified into five groups based on quintiles of total cholesterol (TC) level, and differences in patient characteristics and survival were evaluated.

RESULTS

Patients with low TC had significantly lower low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, triglycerides (TG), sodium, albumin, left ventricular ejection fraction, and cardiac output. The TC quintiles were similar in terms of HF etiology, hypertension, diabetes, and lipid-lowering therapy at time of referral. TC, LDL, HDL, and TG each predicted survival (P < or = .01) on univariate analysis, with improved survival at higher levels. After adjustment for risk factors using a Cox proportional hazards model, relative risks were 2.071, 1.369, 1.391, 1.006 for the first, second, third, and fourth TC quintiles, with quintile 5 as reference.

CONCLUSIONS

Serum TC represents a novel prognostic factor for patients with advanced HF. Further studies are necessary to investigate a potential role of low cholesterol and lipoproteins in the pathophysiology of HF progression.