Interpreting Galectin-3 Results*
Galectin-3 results should be interpreted in conjunction with clinical evaluation as an aid in assessing the prognosis of patients diagnosed with chronic heart failure.
Patients with chronic heart failure with galectin-3 levels over 17.8 ng/mL were found to have a higher risk of adverse outcomes, including mortality or hospitalization, compared to patients with levels below 17.8 ng/mL. Galectin-3 levels between 17.8 ng/mL and 25.9 ng/mL should be interpreted with caution because these values lie within the reference range.
Interpretation Relative to Natriuretic Peptides*
Galectin-3 and natriuretic peptides are measures of separate and distinct biological processes. Each marker provides independent and complementary information on the prognosis of patients with chronic heart failure.
Galectin-3 identifies a subset of patients with chronic heart failure who suffer from an inherently progressive form of heart failure due to galectin-3-mediated fibrosis and adverse remodeling. In a typical NYHA class II/III patient population, the prevalence of galectin-3 elevation (levels > 17.8 ng/mL) is approximately 30%. Galectin-3 testing is indicated for use in patients previously diagnosed with chronic heart failure and cannot be used to rule in or rule out heart failure.
Galectin-3 differs markedly from natriuretic peptides. When interpreting galectin-3 results, it is important to note that:
- Galectin-3 levels are NOT affected by decompensation; they reflect the presence or absence of an underlying disease process. Galectin-3 is only indicated for use in patients with chronic heart failure.
- Once elevated, galectin-3 levels are generally very stable over time.
- Galectin-3 values should not be used to monitor pharmacologic therapies used in the treatment of heart failure.
When reviewing published articles about galectin-3, it is important to note which assay was used in the investigation. Results obtained with research use only assays cannot be compared to those obtained with the BGM Galectin-3 assay. Additionally, investigators may have used cut-points different from the 17.8 and 25.9 ng/mL in the analysis. These alternative cut-points have not been investigated for clinical use and are not recommended.
Galectin-3 and Prognosis in Patients with Chronic Heart Failure
Galectin-3 levels higher than 17.8 ng/mL are indicative of galectin-3 mediated heart failure, which is inherently progressive. Galectin-3 levels over 17.8 ng/mL are associated with an increased risk of adverse outcomes.
The following was observed in controlled studies evaluating the performance of galectin-3 in patients with chronic heart failure:
- Galectin-3 is an independent predictor of adverse outcomes in patients with chronic heart failure.
- Outcomes associated with galectin-3 levels include: combined endpoint of all-cause mortality or hospitalizations and certain individual endpoints such as mortality and hospitalizations for heart failure.
- In studies that are adequately powered to perform such analysis, the galectin-3 effect remains significant after adjusting for variables such as age, gender, NYHA classification, LVEF, smoking, diabetes, kidney function, and natriuretic peptides. A minimum of 500-900 evaluable patients is generally required for such analysis.
Clinical Utility of Galectin-3
What should clinicians do when galectin-3 levels are above 17.8 ng/mL suggesting galectin-3-mediated heart failure?
Physicians should consider this finding in conjunction with customary clinical parameters. The presence of elevated galectin-3 in chronic heart failure conveys two related messages:
- Increased risk for adverse outcomes
- Presence of galectin-3-mediated fibrosis and adverse remodeling
Knowledge of a higher risk for adverse outcomes may contribute to decision making related to aspects of patient management such as (1) spacing of visit intervals; (2) need for specialist referral; (3) timing and methods of discharge planning; and (4) selection of patients for disease management programs or telemonitoring.
The availability of the galectin-3 test is expected to fuel further investigation as to the best treatment options for certain categories of patients with heart failure. Until these approaches have been validated, patients with chronic heart failure with levels of galectin-3 over 17.8ng/mL should be treated in accordance with established guidelines, including the appropriate use of aldosterone antagonists. Ultimately, specific galectin-3 inhibitors may become available.
Levels of galectin-3 in blood may be increased in patients with certain forms of advanced cancer and other conditions associated with organ fibrosis. Galectin-3 results should be interpreted with caution in such patients.
The BGM Galectin-3 ELISA is subject to certain interferences commonly found with similar products. For example, presence of human anti-mouse antibodies (HAMA) or rheumatoid factor (RF) may interfere with the BGM Galectin-3 assay, which could cause falsely elevated results. The BGM Galectin-3 assay should not be used in patients with known HAMA or RF. BGM Galectin-3 results should be interpreted with caution in patients with a history of therapeutic use of murine monoclonal antibodies (IgG) or their fragments, or who have known autoimmune disorders.
Additionally, specimens with high levels of gamma globulins (> 2.5 g/dL) may cause false elevation in results. Galectin-3 results from patients with diseases associated with hyperglobulinemia, such as multiple myeloma, should be interpreted with caution.
For further details on possible interferences and other limitations of the BGM Galectin-3 assay, please see the Package Insert.
* Refer to the BGM Galectin-3 Package Insert for complete information.