The last post in this series discussed new advances in cardiology – the two themes of genetically informed therapy and technical advances. I will continue with three additional themes – regenerative medicine, minimally invasive approaches and prevention.
The third of the five themes is regenerative medicine. One major area of investigation is whether stem cells can heal the damaged heart. Perhaps the field is “more glamour than fact” just now but progress is being made. Among the questions are: What is the correct cell type to use (mesenchymal stem cells, local cardiac progenitor cells, peripheral blood stem cells, etc?). What is the best delivery route (intravenous infusion, infusion into the coronary arteries, injection at time of open surgery, etc?). And what are the longer term consequences of cellular regeneration therapy?
In recent years there has been a wealth of attempts to deliver various stem cell types to patients after myocardial infarction. Some have had modest positive results. Bone marrow stem cells have been shown to increase contractility and improve heart muscle oxygenation and increased patients’ exercise tolerance. There is an increased interest in C-Kit+ cells which are multipotent and can give rise to endothelial, myocardial and smooth muscle cells. They apparently have a key regulatory role in angiogenesis and in the infracted myocardium can drive the repair process. In congestive heart failure, mesenchymal cells seem to help some but the myocyte progenitor C-Kit+ cells appear to have better activity. One source of C-Kit+ cells is from a biopsy of the right atrium. The numbers obtained are small so they need to be multiplied in the laboratory before being replaced into the heart. An experiment in progress is to take C-Kit+ cells from the right atrium at the first palliative surgery of infants with hypoplastic single ventricles, multiply them and implant them three months later at the time of the second scheduled palliative surgery. It will be interesting to see how these cells may or may not assist development of the ventricle. In the laboratory, stem cells can be shown to improve heart function and there is a growing hope that cellular therapies could improve congenital heart diseases sufficiently to avoid the need for a heart transplant.
New data shows that the earliest stem cell that leads to all of the hearts cell types – contracting muscle, smooth muscle and vessels– is the ISL1+ progenitor cell. These can be found in the developing embryo at just the places where major congenital anomalies develop such as the ascending aorta.
The fourth theme is continuing advances in minimally invasive approaches. The advent of angioplasty and stents led the way and replaced many cases of open surgery. Coronary artery bypass surgery itself is increasingly done in less invasive manners and with robotics. Although robotic surgery can be used to do less invasive surgery it is essential that the operator does it regularly and becomes highly proficient. Percutaneous LVADs and percutaneous valve repair and replacement are other examples of less invasive approaches. Overall, invasive procedures are down with the recognition that less invasive or even medical approaches are often as good. Certainly there will be continued and possibly greater use of angioplasty and stent placement for acute infarcts – an approach that has been clearly shown to be beneficial. The most critical problem now is assuring that every patient who needs these procedures gets them and gets them in the needed short time frame after initial symptoms begin.
The fifth theme is prevention. There is a greater intersection today of integrative medicine approaches with traditional western medicine with a greater awareness of the importance of emotional and spiritual health in preventing, slowing the progression of and even helping to reverse heart disease. The work, for example, of cardiologist Dean Ornish demonstrated that a program of a low fat diet, meditation, support groups and moderate stretching and exercise daily had a salutary benefit for those with preexistent coronary artery disease with objective reductions in angiographically proven plaques and PET scan abnormalities. In a Duke study, a multidimensional intervention based on integrative medicine principles reduced the risk of CHD. Risk was reduced compared to standard therapy when participants were taught and encouraged to make use of, as appropriate to the patient’s own situation, mindfulness meditation, stress reduction techniques, relaxation approaches and motivational techniques.
Some “nutraceuticals” may become the next important dugs – fish oils to prevent atherosclerosis; docosahexaenoic acid (DHA) and perhaps eicosapentaenoic acid (EPA) to help reverse or at least slow the progression of heart failure; EPA and perhaps DHA for those with elevated LDL and DHA for those with advanced coronary artery disease. Although we are routinely encouraged to consume cold water fish, the average American only takes in about 150 mg per day of which is well below the recommended level of about 650 mg DHA and EPA combined per day. Since fish obtain their omega 3 fatty acids from algae, it has been found possible to extract the DHA and the EPA from the algae and make it available in capsule form. In one study it was found that adhering to a Mediterranean diet with some fish each week supplemented with 900 mg per day of DHA/EPA would reduce the incidence of cardiovascular death by 45% among those who have had a prior myocardial infarct. A study reported in April, 2011 compared patients with nonischemic dilated cardiomyopathy heart failure given very high doses of DHA/EPA supplements or a placebo and followed for one year. Ejection fraction was increased by about 10%, exercise tolerance increased and hospitalizations were marked decreased from 30% among the placebo group over the 12 months to only 6%.
Cardiac care is advancing rapidly. Genomics is allowing more effective drug therapy; stem cells are continuing to be studied with promising results, many new technologies such as percutaneously repairing or replacing heart valves are being approved, more and more procedures are done less invasively or not at all. And most importantly it is clear that coronary artery disease can be largely prevented with attention to diet, exercise, stress and not smoking perhaps with the added assistance of nutraceuticals.
Stephen C. Schimpff is an internist, professor of medicine and public policy, and former CEO of the University of Maryland Medical Center. He is the author of The Future of Medicine — Megatrends in Healthcare and blogs at Medical Megatrends and the Future of Medicine.
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