In clinic a person asks me about the dose of the statin he is on.

"I don't think we know."

"What do you mean, we don't know."

He is on a statin for a TIA. Transient ischemic attack. I try to explain. We are trying to reduce the risk of a stroke.

I've been in medicine for thirty years and it is changing fast. So the dose of statin is unknown for TIAs. The dose of statin has more evidence for heart disease and heart attacks and sudden death. The last guidelines for statins recommended high dose statins for anyone with known coronary artery disease and anyone with diabetes. For people with an LDL over 190 or a ten year risk calculator of over 7.5%, the recommendation is a moderate dose statin. He is on a low dose.

"What about cutting the dose in half?"

I think about it, checking the neurologist's note.

"She does not say anything about dose. The thing is, you are on a low dose. If you cut that in half, it's a pediatric dose. I recommend sticking."

I show him the US Preventative Services Task Force site. "Also, these are the recommendations in the US. Canada is different, the UK is different, and it all changes as new evidence arrives." I talk about levels of evidence. I give the most weight to the taskforce, where it is multidisciplinary and they do not have skin in the game. That is, I give less weight to the society of radiologists yelling mammograms every year. They make money off it.

"The recommendations change." I say. "Thirty years ago we were not adding a statin routinely for a TIA."

"Why should I do the echocardiogram?" he asks.

"The neurologist wants it to measure your left atrium in your heart. If the atrium is enlarged, you are more likely to be going in and out of atrial fibrillation. In atrial fibrillation, the atria, the chambers at the top of the heart, are not beating. They are twitching. A clot can form and then if the heart goes back to sinus rhythm, that can be the source of the clots causing the TIA. If the atria is enlarged, we will do a three week heart monitor. If you are going in and out of atrial fibrillation, we would recommend a different blood thinner than aspirin. Coumadin, most likely."

"Would imaging show that the statin is decreasing blockage in the arteries in my neck?"

"No. I don't think so. And since the imaging involves dye in the arteries, it has risks. There are studies where they are doing heart catheterizations and then changing diet and lifestyle and then repeating the cath, but it's a study. If you want to look for a study in Seattle, I support that."

"No." he says. He decides to stay on the aspirin, stay on the statin and proceed with the echocardiogram. He has already had a brain MRI, MRA of the carotid and brain arteries, seen the neurologist who agrees that the event was consistent with a TIA, and had an ECG. Next is the echocardiogram.

"The treatment changes over time. This is the best we have at this time and it will change."

He is not comfortable that medicine is a moving target, not a cookbook. But he understands.