About a year and a half ago I injured my back fairly severely. I was relatively immobile for several days (although I continued to work), and one night the pain became so unbearable that I took a (appropriately-prescribed) narcotic pain reliever. A short while later I was able to move around a bit better, but as I was climbing down the stairs I began to experience some shortness of breath and a pressure sensation in my mid-chest.
I've been putting off writing about certain aspects of heart disease for a long time. I'm very comfortable writing about the medical prevention and treatment of heart disease---this is a big part of my practice, and I'm pretty familiar with the literature. But when medication either fails or is not the optimal treatment, the literature explodes with huge, well-done studies often with conflicting conclusions.
Over the last several days, well-known blogger PZ Myers of Pharyngula has written of his new journey into the world of heart disease. He's written a very humorous and human account of his own angioplasty (contributing to the evidence against the claim that he is demon-spawn). This seems a unique opportunity to try to shed a bit of light on the invasive treatment of coronary heart disease.
The heart requires an uninterrupted source of oxygen in order to function properly. This is supplied by the coronary arteries, which take off from the aorta immediately after it exits the heart. These vessels receive blood when it is at it's highest pressure and highest oxygen content (more or less).
Over time, these arteries can develop plaques on their inner surfaces (atherosclerosis). These plaques are caused by a combination of factors, including inherited an genetic predisposition, hypertension, diabetes, and tobacco use. All of these can contribute to inflammation of the plaque, which can rupture, blocking the artery and cutting off the blood/oxygen supply to part of the heart muscle. Without oxygen, this part of the muscle will soon stop beating and die. We call that a myocardial infarction, or heart attack.
We know a great deal about primary and secondary prevention of heart disease. The risk factors we can control (i.e., not the patient's genetics) can be treated aggressively with life style modification and medication. (I've addressed this extensively in earlier posts.) But acute and established heart disease can also be treated invasively.
It's not unusual for the first recognized symptoms of coronary heart disease to be a heart attack, but often their are warnings such as chest pain or difficulty breathing with physical activity. These symptoms often lead to some sort of intervention.
This is a procedure that can be used either in a heart attack or in symptomatic heart disease that hasn't yet resulted in a heart attack. The current terminology, preferred because it is a general term, is "percutaneous coronary intervention" (PCI). In PCI, the procedure that PZ just underwent, a catheter is placed in an artery in the arm or groin, and threaded into the heart.
If blockages are identified, the cardiologist can inflate a balloon to open the artery and (usually) place stent, a sort of metal scaffolding.
Coronary artery bypass grafting (CABG, or "cabbage") is a procedure where the chest is cut open and the blockages are bypassed by placing a vein or artery to take blood from above the blockage and deliver it below.
From the description, it's pretty clear that CABG is far more invasive than than PCI, but these procedure have different roles, and as I mentioned earlier, the data are often conflicting.
In places were angioplasty is not available, clot-dissolving drugs can be given to stop a heart attack in progress. Both procedures effectively halt a heart attack, but a follow up intervention such as PCI or CABG is usually needed for more definitive therapy. CABG is occasionally done in this setting, but that's another story.
Symptomatic Coronary Heart Disease
In patients having symptoms caused by blocked arteries, the data become more difficult. Often, medical therapy alone is as good as PCI. In cases where intervention seems more appropriate, there are several factors to consider in choosing PCI vs. CABG. Part of this depends on the outcome you look at. If you look at the need for re-intervention, you get one answer; mortality, another answer; future heart attack, yet another answer. Also important is the extent of the disease and concurrent risk factors. Some patients simply don't have an anatomy amenable to PCI. If they have multiple vessels involved or are diabetic, there is evidence that CABG is a better choice (once again, depending on the outcome we're looking at).
PZ described having been called to the hospital for an angiogram, after a visit to the hospital for an episode of suspicious chest pain. He told us that several stents were placed. These may have been placed in a single vessel or multiple vessels. These days, chances are the stents are coated with drugs that help prevent re-occlusion of the artery, and these types of stents require prolonged use of anti-platelet drugs. These drugs are very both useful and necessary, but come with their own set of problems.
Our understanding of heart disease, its prevention, and treatment has expanded rapidly over the last three decades. We have never had so many useful tools available for the treatment and prevention of heart disease, and despite the inconsistencies in the data, people are doing much better than they ever have. In the year 2000 alone, approximately 340,000 heart disease deaths were prevented by the modern approach to heart disease, even with the uncertainties.
On the night I had trouble breathing, I thought I was having a panic attack. It seemed logical that the narcotic---a drug I'm not accustomed to taking---was contributing to my "not feeling right". But I couldn't talk myself down from my symptoms. My relative inactivity put me at risk for developing a blood clot in my leg which could travel to my lung, and my high cholesterol put me at risk for heart disease. I spent the evening at the ER, and a number of tests confirmed my original hypothesis---my heart an lungs were fine, so I was probably having a panic attack, an experience I hadn't had either before or since.
Hlatky, M., Boothroyd, D., Bravata, D., Boersma, E., Booth, J., Brooks, M., Carrié, D., Clayton, T., Danchin, N., & Flather, M. (2009). Coronary artery bypass surgery compared with percutaneous coronary interventions for multivessel disease: a collaborative analysis of individual patient data from ten randomised trials The Lancet, 373 (9670), 1190-1197 DOI: 10.1016/S0140-6736(09)60552-3
Hansson, G. (2005). Inflammation, Atherosclerosis, and Coronary Artery Disease New England Journal of Medicine, 352 (16), 1685-1695 DOI: 10.1056/NEJMra043430
Serruys, P., Morice, M., Kappetein, A., Colombo, A., Holmes, D., Mack, M., Ståhle, E., Feldman, T., van den Brand, M., Bass, E., Van Dyck, N., Leadley, K., Dawkins, K., & Mohr, F. (2009). Percutaneous Coronary Intervention versus Coronary-Artery Bypass Grafting for Severe Coronary Artery Disease New England Journal of Medicine, 360 (10), 961-972 DOI: 10.1056/NEJMoa0804626