Decreasing Risks After Heart Transplantation
By Amanda Chase, PhD
April 22, 2020
Heart failure, or the inability of the heart to pump enough blood to meet the needs of the body, is a very common condition. Although there is no cure for heart failure, there are available treatments to allow longer and more active lives. Heart failure can progress to the point where lifestyle changes and medications no longer control symptoms, and a heart transplant is then considered. Heart transplantation is not without significant side effects, including atrial fibrillation (AF; irregular heartbeat) or venous thromboembolism (VTE; blood clot starting in vein of leg, groin, or arm). Both AF and VTE lead to an increased risk of blood clots, which can lead to heart attack or stroke. A team at Stanford led by Erik Henricksen, PharmD, and Maxime Tremblay-Gravel, MD, and senior author Kiran Khush, MD, aimed to understand the best course of treatment to prevent blood clots in heart transplantation patients. Their results were recently published in the Journal of Heart and Lung Transplantation.
VTE, or blot clot formation in veins, is the third leading vascular diagnosis, behind heart attack and stroke, with 300,000 – 600,000 affected yearly. VTE is a common, preventable cause of death, and thus reducing incidences has a huge potential public health benefit. Atrial fibrillation is an irregular heartbeat that disrupts blood flow and leads to an increased risk of blood clots forming in the heart. Patients are put on blood thinners, or anticoagulants, to treat and/or prevent the formation of blood clots. Historically, warfarin was the most commonly prescribed anticoagulant, but it requires frequent monitoring with monthly blood draws, several dietary restrictions, and has many known adverse interactions with other drugs. Newer drugs, direct oral anticoagulants (DOAC), are now available, but there is limited guidance for use, particularly after transplantation. DOACs have an advantage of requiring less monitoring, having fewer drug and food interactions, and they begin to work faster than warfarin. This study compared DOACs to warfarin after heart transplant, looking at 73 heart transplant patients who had received anticoagulants between January 2012 and July 2019 for AF or VTE.
The authors showed that, compared to warfarin, DOAC therapy resulted in a lower risk of bleeding that required transfusion. In addition, they found that administration of DOACs appeared to be safe and well tolerated by heart transplant recipients. Importantly, this was the largest study in heart transplantation treated with DOACs to-date. It provides evidence that DOACs are an acceptable alternative to warfarin for heart transplant patients, and may even provide benefits over warfarin. While this study calls for additional studies with larger cohorts to validate the findings, it provides an important step towards addressing the public health need for better treatment options for AF and VTE in high risk populations.
Other Stanford-affiliated authors include Yasbanoo Moayedi, Wenjia Yang, Roy Lee, William Hiesinger, and Jeffrey Teuteberg. Heather Ross from University Health Network, Toronto was also a contributing author.