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Revealing the Need for Additional Research
Pulmonary Hypertension Risk in Thalassemia Underappreciated

October, 2011 - A new study conducted through the Thalassemia Clinical Research Network (TCRN) indicates that many patients with Thalassemia major are at risk for pulmonary hypertension. An elevated tricuspid regurgitant jet velocity (TRV) on Doppler echocardiogram (ultrasound of the heart and lungs) is more prevalent than expected in the thalassemia population. A high TRV identifies patients at risk for pulmonary hypertension (PH) , however it is not associated with short-term increased mortality in this patient population as typically seen in other blood disorders like sickle cell disease.

"High TRV is a biomarker for risk of pulmonary hypertension, a potentially life-threatening condition in which the blood pressure going from the heart to the lungs is elevated. This means that if a patient has an elevated TRV, they are at an increased risk for PH," explains CHORI clinical scientist, pediatric emergency medicine physician and first author, Claudia Morris, MD.

“Pulmonary hypertension, a potentially life-threatening condition in which the blood pressure going from the heart to the lungs is elevated.”

"Previous research has shown a 40 percent mortality rate within four years associated with an elevated TRV in patients with sickle cell disease, so we wanted to determine if the same was true with thalassemia patients," says Dr. Morris.

Pulmonary hypertension is a condition associated with increased mortality, and is a complication that can occur with many different conditions across many different specialties. Over the past few decades, there has been a growing appreciation for the fact that PH is a complication of hemolytic blood disorders, such as sickle cell disease and thalassmia.

“In thalas-
semia in particular, the literature over the last 20 years has demonstrated an over-
whelming amount of evidence of PH being a problem , but very little to date has been done on how to go about treating it.”

As a starting point to understand the extent of the problem,  Dr. Morris and Children’s Hospital Oakland Hematology/Oncology Director, Elliott Vichinsky, MD, and their colleagues, utilized data through the TCRN, the National Institutes of Health (NIH)-sponsored network of international hematology centers, in order to assess the incidence, risk factors and clinical implications of an elevated TRV  in thalassemia patients treated at 16 different centers.

“Elevated TRV levels can be captured during routine Doppler echocardiograms by simply measuring the amount of regurgitated blood that passes across the valve that separates the right atrium from the right ventricle, an indication that PH could be present,” explains Dr. Morris.

The results of the study indicate that high TRV levels are common in the thalassemia population. However no patients in this group  with high TRV levels  received a follow up evaluation by cardiac catheterization to definitively determine if in fact they had true pulmonary hypertension,  or to determine if treatment was warranted.

"It is important that hematologists who routinely care for thalassemia patients refer patients to cardiologists with expertise in PH  diagnosis and treatment when there are indications that certain thalassemia patients may be at risk for PH,” says Dr. Morris.  “Everyone really needs to be at the same table so that the experts in each area are working together.”

Additional results of significant note include the fact that there was a high prevalence of elevated TRV in children as well as in adults. Older patients were at a higher risk of having an elevated TRV, but  advancing agevwas also associated with hepatitis C or having had their spleens removed, both of which are known to be associated with PH.

"The biggest observation, and perhaps the most significant, was that the mortality was very low," says Dr. Morris.

“In the thalassemia population, unlike in patients with sickle cell disease, having a high TRV alone was not a significant red flag that the patient was going to die early.”

."The fact that this same biomarker in sickle cell disease patients isn't associated with similar mortality rates in thalassemia is very encouraging news, and perhaps suggests alternate pathophysiology," says Dr. Morris.

While the lack of significant mortality rates in thalassemia patients with elevated TRV was a welcome discovery, the results of the study as a whole underscore the need for longterm follow-up and randomized controlled trials of PH in thalassemia.

"Folks have been talking about PH in thalassemia for years, and we really need to address its role so that we can learn how PH may or may not differ in the thalassemia population from other patient populations in which PH is prevalent, and offer treatment options to patients who may benefit from it" says Dr. Morris.


Tuesday, November 15, 2011 11:23 AM

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