Europe, especially the U.K., has become much enamored of statins in recent years. The U.K. now has the dubious distinction of being the only country where statins can be purchased over-the-counter, and the amount of statin consumption there has increased more than 120% in recent years (Walley et al, 2005). Increasingly, orthopedic clinics are seeing patients whose problems turn out to be solvable by simply terminating statin therapy, as evidenced by a recent report of three cases within a single year in one clinic, all of whom had normal creatine kinase levels, the usual indicator of muscle damage monitored with statin usage, and all of whom were "cured" by simply stopping statin therapy (Shyam Kumar et al., 2008). In fact, creatine kinase monitoring is not sufficient to assure that statins are not damaging your muscles (Phillips et al., 2002).
Since the liver synthesizes much of the cholesterol supply to the cells, statin therapy greatly impacts the liver, resulting in a sharp reduction in the amount of cholesterol it can synthesize. A direct consequence is that the liver is severely impaired in its ability to convert fructose to fat, because it has no way to safely package up the fat for transport without cholesterol (Vila et al., 2011). Fructose builds up in the blood stream, causing lots of damage to serum proteins.
The skeletal muscle cells are severely affected by statin therapy. Four complications they now face are: (1) their mitochondria are inefficient due to insufficient coenzyme Q10, (2) their cell walls are more vulnerable to oxidation and glycation damage due to increased fructose concentrations in the blood, reduced choleserol in their membranes, and reduced antioxidant supply, (3) there's a reduced supply of fats as fuel because of the reduction in LDL particles, and (4) crucial ions like sodium and potassium are leaking across their membranes, reducing their charge gradient. Furthermore, glucose entry, mediated by insulin, is constrained to take place at those lipid rafts that are concentrated in cholesterol. Because of the depleted cholesterol supply, there are fewer lipid rafts, and this interferes with glucose uptake. Glucose and fats are the main sources of energy for muscles, and both are compromised.
As I mentioned earlier, statins interfere with the synthesis of coenzyme Q10 (Langsjoen and Langsjoen, 2003), which is highly concentrated in the heart as well as the skeletal muscles, and, in fact, in all cells that have a high metabolic rate. It plays an essential role in the citric acid cycle in mitochondria, responsible for the supply of much of the cell's energy needs. Carbohydrates and fats are broken down in the presence of oxygen to produce water and carbon dioxide as by-products. The energy currency produced is adenosine triphosphate (ATP), and it becomes severely depleted in the muscle cells as a consequence of the reduced supply of coenzyme Q10.
The muscle cells have a potential way out, using an alternative fuel source, which doesn't involve the mitochondria, doesn't require oxygen, and doesn't require insulin. What it requires is an abundance of fructose in the blood, and fortunately (or unfortunately, depending on your point of view) the liver's statin-induced impairment results in an abundance of serum fructose. Through an anaerobic process taking place in the cytoplasm, specialized muscle fibers skim off just a bit of the energy available from fructose, and produce lactate as a product, releasing it back into the blood stream. They have to process a huge amount of fructose to produce enough energy for their own use. Indeed, statin therapy has been shown to increase the production of lactate by skeletal muscles (Pinieux et al, 1996).
Converting one fructose molecule to lactate yields only two ATP's, whereas processing a sugar molecule all the way to carbon dioxide and water in the mitochondria yields 38 ATP's. In other words, you need 19 times as much substrate to obtain an equivalent amount of energy. The lactate that builds up in the blood stream is a boon to both the heart and the liver, because they can use it as a substitute fuel source, a much safer option than glucose or fructose. Lactate is actually an extremely healthy fuel, water-soluble like a sugar but not a glycating agent.
So the burden of processing excess fructose is shifted from the liver to the muscle cells, and the heart is supplied with plenty of lactate, a high-quality fuel that does not lead to destructive glycation damage. LDL levels fall, because the liver can't keep up with fructose removal, but the supply of lactate, a fuel that can travel freely in the blood (does not have to be packaged up inside LDL particles) saves the day for the heart, which would otherwise feast off of the fats provided by the LDL particles. I think this is the crucial effect of statin therapy that leads to a reduction in heart attack risk: the heart is well supplied with a healthy alternative fuel.
This is all well and good, except that the muscle cells get wrecked in the process. Their cell walls are depleted in cholesterol because cholesterol is in such short supply, and their delicate fats are therefore vulnerable to oxidation damage. This problem is further compounded by the reduction in coenzyme Q10, a potent antioxidant. The muscle cells are energy starved, due to dysfunctional mitochondria, and they try to compensate by processing an excessive amount of both fructose and glucose anaerobically, which causes extensive glycation damage to their crucial proteins. Their membranes are leaking ions, which interferes with their ability to contract, hindering movement. They are essentially heroic sacrificial lambs, willing to die in order to safeguard the heart.
Muscle pain and weakness are widely acknowledged, even by the statin industry, as potential side effects of statin drugs. Together with a couple of MIT students, I have been conducting a study which shows just how devastating statins can be to muscles and the nerves that supply them (Liu et al, 2011). We gathered over 8400 on-line drug reviews prepared by patients on statin therapy, and compared them to an equivalent number of reviews for a broad spectrum of other drugs. The reviews for comparison were selected such that the age distribution of the reviewers was matched against that for the statin reviews. We used a measure which computes how likely it would be for the words/phrases that show up in the two sets of reviews to be distributed in the way they are observed to be distributed, if both sets came from the same probability model. For example, if a given side effect showed up a hundred times in one data set and only once in the other, this would be compelling evidence that this side effect was representative of that data set. Table 1 shows several conditions associated with muscle problems that were highly skewed towards the statin reviews.
I believe that the real reason why statins protect the heart from a heart attack is that muscle cells are willing to make an incredible sacrifice for the sake of the larger good. It is well acknowledged that exercise is good for the heart, although people with a heart condition have to watch out for overdoing it, walking a careful line between working out the muscles and overtaxing their weakened heart. I believe, in fact, that the reason exercise is good is exactly the same as the reason statins are good: it supplies the heart with lactate, a very healthy fuel that does not glycate cell proteins.