Biomarker IDs Fibrotic Heart Failure
Galectin-3 (Gal-3), a biomarker for fibrosis, may have a role in identifying heart failure caused by cardiac amyloidosis, researchers suggested.
Levels of Gal-3 were significantly more elevated in patients with cardiac amyloidosis compared to those with left ventricular (LV) hypertrophy (P<0.050) and those with systolic heart failure (P<0.05), according to Eitan A. Friedman, MD, of Vanderbilt University in Nashville, Tenn., and colleagues.
Although levels of Gal-3 were elevated in the other two groups as well, researchers found no differences between those two groups in the biomarker levels, they reported here at the annual meeting of the Heart Failure Society of America.
"The challenging thing in the case of amyloidosis is that heart function is normal as best we can tell from echo, but these patients have very significant heart failure symptoms," senior author Daniel Lenihan, MD, explained to MedPage Today. "The heart muscle can't relax because it is infiltrated by amyloid."
Patients with amyloidosis often present with LV hypertrophy on echo, making the diagnosis of amyloidosis difficult. "The important element here is that noninvasive testing or symptoms cannot discriminate between these different groups of patients," Lenihan said.
"That is why we are searching for other markers that can tell us if amyloid is involved, because early recognition and treatment can improve outcomes in cardiac amyloidosis," he said.
One potential therapy for cardiac amyloidosis is treatment with cardiac stem cells, which has shown some promise in small studies. Drug companies are also trying to find a treatment for the disease.
For the study, Friedman and colleagues evaluated 34 patients with cardiac amyloidosis (mean age 61), 43 patients with LV hypertrophy (mean age 54), and 42 patients with systolic heart failure (mean age 56).
They collected serum from patients in Vanderbilt's main heart registry in the following groups:
- Cardiac amyloidosis (systemic amyloidosis plus positive biopsy, MRI, EKG, or echo)
- LV hypertrophy (LV mass index greater than 115 g/m2 in men and greater than 95 g/m2 in women with relative wall thickness greater than 0.44)
- Systolic heart failure (LV ejection fraction at 30% or lower and NYHA class at III or greater)
Gal-3 levels in the three groups, respectively, were:
- 34.4 ng/mL
- 19.8 ng/mL
- 24.0 ng/mL
The mean LV ejection fraction was lowest in systolic heart failure (20%) compared with cardiac amyloidosis (53%) and LV hypertrophy (61%).
The mean NYHA class was 2.5 for cardiac amyloidosis, 1.8 for LV hypertrophy, and 3.2 for systolic heart failure. Those with systolic heart failure had the highest LV mass index and the lowest relative wall thickness compared with the other two groups.
In this study, the patients had already been diagnosed prior to their blood test. The next step, Lenihan said, is to determine whether Gal-3 is elevated in patients suspected of having amyloidosis. "We'd like to know if a galectin-3 blood test could help detect amyloid at an earlier point where treatment might be more effective," he said.
A study from the National Heart, Lung, and Blood Institute found that levels of Gal-3 were associated with an increased risk of heart failure and death. The mean follow-up was 9 years and it was the first time that Gal-3 was shown to have a relationship with future heart failure.
"The take-home message is that galectin-3 may be an early indicator of fibrosis in cardiac amyloidosis and measuring it may be a proactive approach to prove or confirm the diagnosis," Lenihan said, adding that more research is needed.
The next step would be to conduct prospective studies. However, at Vanderbilt, the blood test for Gal-3 is being used to confirm diagnosis of cardiac amyloidosis and to help guide treatment, Lenihan said.
The study had limited value because it was from a single center, was retrospective, and the diagnosis of cardiac amyloidosis was known in advance.
Source: www.medpagetoday.com
