Results from a large, retrospective study conducted at City of Hope National Medical Center indicate that patients who receive stem cell transplants are at a higher risk of developing heart disease than the general population.

The researchers found that patients who underwent a donor transplant and developed graft-versus-host disease, a common transplant-related complication, were at the greatest risk of developing heart disease.

“Our findings show that the process of receiving a stem cell transplant alone increases a recipient’s risk of developing heart disease,” said the study’s lead investigator Dr. Saro Armenian from City of Hope in Duarte, California, in a press release. “However, the type of transplant and whether the recipient was treated for [graft-versus-host disease] can also increase that survivor’s heart disease risk,” he added.

The researchers believe that their data could be used to identify patients who have an increased risk for heart disease and therefore need close monitoring and management of the risk factors.

“The results of this study demonstrate the importance of intervention strategies that can help mitigate these modifiable heart disease risk factors in transplant recipients before and after transplant, and we hope they can serve as a basis for creating a predictive model to identify those patients at highest risk of developing heart disease,” said Dr. Armenian.

According to Dr. Armenian and his colleagues, heart disease is one of the leading causes of death after stem cell transplantation.

In the general population, high blood pressure, diabetes, and high cholesterol levels are risk factors that have been associated with the development of heart disease.

The researchers point out that patients receiving stem cell transplants may be at an increased risk of developing these risk factors because of the high-dose chemotherapy used during the procedure as well as the development of transplant-related complications.

Previous studies that sought to evaluate these heart disease risk factors in patients receiving stem cell transplants were limited by small patient populations and short follow-up times.

In order to more thoroughly assess the heart disease risk factors and development of heart disease in patients who received stem transplants, Dr. Armenian and his colleagues retrospectively analyzed data from 1,963 patients who received a stem cell transplant for a blood-related cancer at City of Hope between 1995 and 2004. Approximately 15 percent of the patients had multiple myeloma.

“Our study sought to better determine the specific factors before and after transplant that can lead to heart disease in a large group of transplant recipients,” said Dr. Armenian.

The median age at transplant was 44 years, and all patients survived for at least one year following the procedure.

Furthermore, 43 percent of patients received a donor (allogeneic) transplant. An allogeneic transplant involves transplanting a healthy donor’s stem cells into a patient after high-dose chemotherapy. However, multiple myeloma patients most often receive autologous stem cell transplants, in which the patients’ own stem cells are re-infused into their bodies after high-dose chemotherapy.

For the purposes of the study, heart disease risk factors included high blood pressure, diabetes, and high cholesterol levels. Heart disease was measured as the occurrence of heart failure, angina, heart attack, or stroke.

The median follow-up time was 5.9 years.

The researchers found that 36 percent of patients had high blood pressure after their transplant, of which approximately one half had the condition at the time of transplant, and the other half developed it after the transplant. The median time to post-transplant high blood pressure was 0.4 years.

In addition, 17 percent of patients had diabetes after their transplant, of which 55 percent developed the condition after the transplant. The median time to post-transplant diabetes was 1.9 years.

The most common heart disease risk factor was high cholesterol levels (44 percent of patients). Approximately half of the patients (57 percent ) developed this condition after the transplant in a median of 0.5 years.

The investigators also compared risk factors in patients receiving allogeneic versus autologous stem cell transplants. Overall, they found that patients who received allogeneic transplants developed heart disease risk factors significantly faster than those who had autologous transplants.

For instance, the median time to high blood pressure following transplantation was much shorter for allogeneic transplant recipients than for autologous transplant recipients (0.2 years versus 3.7 years).

This trend was also true for post-transplant diabetes (1.2 years versus 3.3 years) and high cholesterol levels (0.2 years versus 1.6 years).

The researchers found that patients who developed graft-versus-host disease after an allogeneic transplant were most vulnerable to heart disease. Graft-versus-host disease is a common allogeneic transplant-related complication in which the donor cells recognize the patient’s cells as “foreign” and attack them.

The results showed that 55 percent of these patients had high blood pressure, 26 percent had diabetes, and 53 percent had high cholesterol after their transplant.

Investigators also found that older age and obesity were significant predictors of these risk factors in transplant patients.

Ultimately, 6 percent of patients developed heart disease at a median of four years after transplant.

Patients who had more risk factors had a higher chance of developing heart disease (5 percent for none, 7 percent for one, and 11 percent for at least two risk factors).

For more information, please see the study in the journal Blood ^[1] (abstract) and the American Society of Hematology ^[2] press release.