When all other options for heart failure therapy have been exhausted, the option of heart transplantation is still open for some patients. At the Heart Failure Congress of the European Society of Cardiology (ESC) in Paris, international experts provided information on current aspects of heart transplantation. Since last year, there have been new guidelines for including heart failure patients on the transplant waiting list.
What are the criteria for selecting patients for heart transplantation? Prof. Mandeep Mehra, Boston (USA), spoke on this question. Initial guidelines were written in 2006, with an update in 2016 [1,2]. Some aspects that were new in 2006 are now routine. For example, many centers no longer have a set “age guillotine,” which used to be 70. And patients who have cancer are no longer required to have a minimum survival time after cancer therapy. The assessment of how long to wait for heart transplantation after tumor remission depends largely on the type of tumor and the risk of recurrence or death. a metastasis. “Even the order of cancer therapy first, then transplantation, is no longer always followed,” Prof. Mehra explained. “In patients with low-malignant prostate cancer, it is sometimes treated after heart transplantation.”
New in the Guidelines: Recommendations on Frailty, HIV and Cannabis
In the current guidelines, the cut-off value for heart transplantation is now a BMI <35 and an HbA1c <7.5. Inclusion of a patient on the waiting list for heart transplantation solely on the basis of peak oxygen uptake (peak VO2) is no longer recommended because different cut-off values may apply to women, young patients, and overweight individuals than to average patients. Instead of age, the degree of frailty is now used as an inclusion or exclusion criterion, because younger people can also be frail. Indications of frailty include weight loss of more than 10 kg in the past year, muscle wasting, slow walking speed, and low physical activity. Also, patients with HIV or chronic HBV/HCV infection are no longer a priori excluded from heart transplantation; under certain circumstances (HIV: no opportunistic infections, good compliance, HIV RNA undetectable), they can be placed on the waiting list.
Cannabis abuse, on the other hand, is more problematic. “We don’t recommend putting patients on the waiting list who can’t detectably stop smoking marijuana,” the speaker said. “These individuals are at increased risk of using other illicit drugs and suffering from cognitive impairment. This has a bad effect on compliance.” In addition, the risk of fungal infections is increased in “potheads”. However, not only marijuana is harmful, but also normal cigarette smoke. Amazingly, one third of all patients start smoking again after a heart transplant! The life expectancy of these patients is also reduced by one-third due to smoking: the median lifespan of a transplanted heart is about 15 years, 4.5 years less for smokers.
Donor hearts after cardiac arrest
In Europe, the number of heart transplants has declined over the past 20 years, while the number of people on the waiting list has tripled since 2002. An organ is available for only about half of those waiting. For this reason, methods are being sought to increase the number of donor hearts. One possibility is “donation after cardiac arrest” (DCD), about which Prof. Steven Tsui, Cambridge (UK), provided information.
Transplantation of a heart after cardiovascular arrest is possible only if the heart does not experience ischemia. There are basically three ways to keep the heart alive in people who die of cardiovascular arrest in the hospital:
- In situ cold cardioplegia: after a brief “no touch” period following the onset of death, the heart is cooled with a cardioplegic solution [3].
- In situ warm perfusion: after death occurs, the heart is immediately harvested and transplanted [4].
- Ex-situ warm perfusion: after death occurs, the heart is removed and perfused outside the body to keep it beating until transplantation (enormously complex).
Which of these options may be used at all depends strongly on regulations in the respective country (definition of death). DCD is fundamentally highly controversial because it involves many ethical questions: when is a person truly dead? And in what cases should it be permissible – if at all – not to resuscitate a person in cardiovascular arrest but to remove his or her heart? Heart transplantation after DCD is being performed in various countries as part of studies. Recent studies from Sydney (Australia) and London and Cambridge (UK) with a total of 47 DCD hearts show promising results: 97.8% of the hearts survived the first 30 days after transplantation, 89.4% the first year. “Transplantation of DCD hearts can significantly increase the number of heart transplants in centers,” Prof. Tsui said.
Immunosuppression and renal insufficiency
Some facts about immunosuppression after heart transplantation were given by Prof. Finn Gustafsson, Copenhagen (Denmark). As better drugs become available to suppress rejection and patients live longer after heart transplantation, the side effects of immunosuppressants are now coming under increased scrutiny. Renal toxicity of ciclosporin is a major problem: about 20% of patients after heart transplantation develop chronic renal failure. This significantly reduces their life expectancy. Everolimus and sirolimus are not nephrotoxic, but switching to one of these agents did not improve renal function in several studies. “The problem is that glomerular filtration rate drops significantly already in the first three weeks after transplantation,” Prof. Gustafsson said. “For this reason, ciclosporin should be discontinued as soon as possible after transplantation or at least the dose should be significantly reduced.” However, this therapy regime also has its price, because without the administration of ciclosporin, rejection reactions occur more frequently. It is important that further studies be conducted to further improve immunosuppression therapy after organ transplantation without compromising patient health from side effects.
Source: “Novel aspects in heart transplantation” symposium, ESC Heart Failure Congress, April 29-May 2, 2017, Paris (F).
Literature:
- Mehra MR, et al: Listing criteria for heart transplantation: International Society for Heart and Lung Transplantation guidelines for the care of cardiac transplant candidates – 2006. J Heart Lung Transplant 2006; 25(9): 1024-1042.
- Mehra MR, et al: The 2016 International Society for Heart Lung Transplantation listing criteria for heart transplantation: A 10-year update. J Heart Lung Transplant 2016; 35(1): 1-23.
- Dhital KK, et al: Adult heart transplantation with distant procurement and ex-vivo preservation of donor hearts after circulatory death: a case series. Lancet 2015; 385(9987): 2585-2591.
- Messer SJ, et al: Functional assessment and transplantation of the donor heart after circulatory death. J Heart Lung Transplant 2016; 35(12): 1443-1452.
HAUSARZT PRAXIS 2017; 12(7): 42-43
CARDIOVASC 2017; 16(4): 32-33
