Despite careful patient selection, only about 75 percent of heart recipients survive three years after the transplant surgery. Identifying the patients most in need of additional care has always been tricky, but now Stanford researchers have found a better way to predict which heart transplant recipients have a higher risk of dying or needing another heart transplant, as reported in Circulation today.
One key reason transplant patients die is cardiac allograft vasculopathy, an accelerated and aggressive form of coronary artery disease.
William Fearon, MD, professor of medicine and senior author, explained the significance of their results in a recent email:
Identifying patients at higher risk of dying from cardiac allograft vasculopathy is helpful, because it allows the transplant physicians to be more aggressive with medical therapy and monitoring than they might otherwise be, in order to hopefully prevent adverse events.
The researchers conducted a clinical trial involving 74 heart transplant recipients, whose heart physiology was invasively assessed within eight weeks and one year after transplantation. They found that two particular diagnostic procedures were able to successfully identify high-risk recipients — fractional flow reserve and index of microcirculatory resistance.
Fractional flow reserve is a procedure that measures the blood pressure and flow through a specific part of the coronary artery. It is often used to determine whether blood flow is significantly obstructed by a blockage or lesion, guiding a cardiologist’s decision of whether to stent the blockage.
Fearon’s team determined that a low fractional flow reserve measured soon after the transplant independently predicted the heart transplant recipients’ risk of death or retransplantation.
Index of microcirculatory resistance measures the functionality of the tiny vessels that supply blood to the heart. Fearon found that a higher than normal reading measured one year after the heart transplant was also an independent predictor of the recipient’s survival.
The Stanford researchers hope that more emphasis will be placed on these two invasive assessments of cardiac physiology in heart transplant recipients, so their medical regimen can be adjusted to improve the odds of their survival.
Previously: Dick Cheney on his heart transplant: “It’s the gift of life itself,” A simple blood test may unearth the earliest signs of heart transplant rejection and Ask Stanford Med: Stanford interventional cardiologist taking questions on heart health
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