Updated April, 2006
A study published in the December 3, 2003 edition of the Journal lf the American College of Cardiology reports a relationship between lower cholesterol levels and increased mortality in patients with heart failure.
The study was conducted in the Royal Brompton Chronic Heart Failure Clinic in London, by investigators who were intrigued by earlier reports suggesting a surprising association betwen lower cholesterol levels and higher death rates in heart failure patients. So they measured cholesterol levels in over 400 patients with varying degrees of heart failure at the Royal Brompton, and followed their outcomes. They found that in these patients, the lower the cholesterol levels, the higher the risk of dying.
Based on data from this and other studies, it can be estimated that heart failure patients whose total cholesterol is below 190 or 200 mg/dL may have a 2 to 3-fold increased risk of dying, compared to similar patients whose cholesterol levels are higher.
DrRich comments:
What does this new finding really mean?When combined with scattered reports from other small observational studies, there is increasingly solid evidence that low cholesterol can be bad in some medical conditions. Patients with severe trauma, multiple organ failure, kidney disease and severe infections have been reported to have worse outcomes when cholesterol levels are low.
The authors of the report cited above speculate that in patients with medical conditions that create high metabolic demand - heart failure and the other medical conditions just mentioned would qualify - cholesterol requirements may simply be higher than in patients without such a metabolic demand. (Cholesterol is required in many key metabolic processes within cells.) If this theory is correct, then reducing cholesterol in patients who have these sorts of conditions may cause more harm than good. However, it cannot be determined accurately from observational studies, such as this one, whether the low cholesterol levels themselves actually cause increased risk, or whether they are merely a marker of a worse prognosis.
In any case, it is especially interesting to note, in this light, that several studies have now indicated that the use of statin drugs improve the outcome of patients with heart failure, and furthermore, the most significant improvement appears to occur in patients who had low cholesterol levels to start with (and therefore were the "sickest"). The accumulated evidence, while not definitive, has convinced many heart failure experts that statins indeed are helpful. If this is the case, then the statins must be acting through some mechanism aside from their cholesterol-lowering properties.
As it turns out, statins have several possible mechanisms by which they could improve heart failure. Statins slow atherosclerisis; they reduce inflammation; they improve vascular function and reduce vascular "stiffness;" they reduce oxidative stress; they tend to normalize the balance of the autonomic nervous system; and they help prevent abnormal blood clotting. So the observation that statins help in heart failure, despite the observation that low cholesterol has a bad prognosis in heart failure, still makes sense.
Two randomized trials are now underway to more definitively answer the question of whether statin therapy improves the outcome of patients with heart failure - the CORONA and the GISSI- HF trials. In the meantime, if doctors feel that the weight of evidence currently supports the use of statins in these patients, many patients with heart failure currently have a legitimate indication for using statins. Such indications would include the presence of known coronary artery disease, diabetes, or LDL cholesterol levels greater than 100.
