New UCLA study reports which patients fare worse after heart transplantation
According to UCLA cardiologists, heart transplant patients are very prone to developing an aggressive form of coronary artery disease, which often results in heart failure, death, or the need for repeat transplantation.
Furthermore, the condition may have a negative impact on future cardiac procedures, such as stenting. UCLA researchers have determined which heart transplant patients are prone to have poor long-term survival. Their study, one of the largest and longest follow-up studies of this patient population, was published in the June 15 edition of the American Journal of Cardiology.
The researchers note that transplant patients are among those at highest risk of adverse outcomes when receiving a stent to address a blockage in an artery. Compared with the general public, these patients have a much higher rate of restenosis, a side effect of stenting in which the artery becomes re-blocked because of an exaggerated scarring process at the stenting site. New research by UCLA researchers and colleagues has found that heart transplant patients who develop restenosis after receiving a stent have poor long-term survival.
“The findings point to the need for improvements in prevention and treatment of transplant coronary artery disease that may help reduce restenosis for patients who require later cardiac procedures like stenting,” noted Dr. Michael Lee, an assistant professor of cardiology at the David Geffen School of Medicine at UCLA. A stenting procedure begins with an angioplasty, in which a catheter is placed in an artery of the groin and a tiny wire is snaked up through the artery to the blocked area of the heart. The clogged artery is cleaned out, and then a stent — a tiny wire-mesh tube — is passed up through the artery and deployed to keep the artery open, allowing blood to flow freely through the heart again.
Dr. Lee noted that, currently, there are no guidelines or treatment recommendations for in-stent restenosis for transplant coronary artery disease. He suggests that a scoring system to help pinpoint risks might help identify good candidates for stenting and other catheter-based procedures.
The study group was comprised of 105 heart transplant patients who underwent a stent procedure at UCLA Medical Center between 1995 and 2009. The patients received either a bare metal stent or, in the later years of the study, a newer medication-coated stent that can help impede restenosis development. At the seven-year follow-up evaluation, the patients who had not developed in-stent restenosis were further from an end-point of death, heart attack, or repeat transplantation (63.2% percent) than patients who had developed restenosis (27.9%). The authors noted that this was primarily due to a lower survival rate in patients who developed restenosis (38.5%) compared to patients who did not (84.2%).
Dr. Lee notes that approximately 50% of heart transplant patients who receive a medication-coated stent develop restenosis, compared with only 5-10% of the general population. To date, transplant researchers have not uncovered the exact mechanism that heightens the risk of death and heart attack as well as an increased need for additional transplant in patients with transplant coronary artery disease who develop in-stent restenosis. Dr. Lee added that organ rejection may contribute to transplant coronary disease and play a role in the increased risk of mortality. The development of blood clots in the arteries, known as intracoronary thrombus, may also contribute to mortality. He explained, “We may find that development of restenosis in heart transplant patients may be a marker of a more aggressive inflammatory response and part of transplant rejection.”
The researcher plan further studies will help better understand the role of other factors in developing transplant coronary artery disease and in-stent restenosis.
UCLA Health System has a robust heart transplant program, which has been operational since 1984. Last August, UCLA announced that their new heart transplant program is now operational. One recent technological advantage currently under investigation is the transport of the donor heart still beating; rather than chilled in an ice chest. The experimental device that keeps the hear warm and beating with oxygen and nutrient-rich blood during transport. UCLA is currently involved in an ongoing national study of an experimental organ-preservation system that allows donor hearts to continue functioning in a near-physiologic state outside the body during transport. The trial is being led by principal investigator Dr. Abbas Ardehali, surgical director of the heart and lung transplantation program at UCLA.
The Organ Care System (OCS), developed by medical device company TransMedics, works this way: After a heart is removed from a donor's body, it is placed in a high-tech OCS device and is immediately revived to a beating state, perfused with oxygen and nutrient-rich blood, and maintained at an appropriate temperature. The device also features monitors that display how the heart is functioning during transport. According to Ardehali, the technology could also improve donor-heart function and could potentially help transplant teams better assess donor hearts — including identifying possible rejection factors that could complicate tissue-matching — since the organs can be tested in the device, over a longer period of time.
UCLA Health System
American Journal of Cardiology