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Evidence from family studies for autoimmunity in dilated cardiomyopathy
A L Caforio1, P J Keeling, E Zachara
1Department of Cardiological Sciences, St George's Hospital Medical School, London, UK.
Insights
Cardiac autoantibodies are present in symptom-free relatives of dilated cardiomyopathy (DCM) patients, suggesting an autoimmune basis for DCM. These antibodies may indicate early cardiac dysfunction and identify at-risk individuals.
Area of Science:
- Cardiology
- Immunology
- Genetics
Background:
- Autoimmune diseases can manifest with organ-specific antibodies years before clinical symptoms.
- Dilated cardiomyopathy (DCM) may have an autoimmune etiology, as suggested by the presence of cardiac autoantibodies in affected individuals and their relatives.
Purpose of the Study:
- To investigate the prevalence of cardiac autoantibodies in symptom-free relatives of DCM patients.
- To determine if cardiac autoantibodies are associated with early signs of cardiac dysfunction or familial DCM.
Main Methods:
- Non-invasive cardiological assessment and antibody screening were performed on 342 symptom-free relatives of DCM patients.
- Relatives were categorized into familial DCM (multiple affected members) and non-familial DCM (single affected member) groups.
Main Results:
- Cardiac antibodies were found in 20% of relatives versus 3.5% in controls (p=0.0001).
- Antibodies were present in 58% of families studied, more common in familial DCM (24%) than non-familial DCM (15%).
- Antibody-positive relatives were younger and showed early signs of left ventricular systolic dysfunction (larger end-systolic dimension, reduced fractional shortening).
Conclusions:
- The presence of cardiac-specific autoantibodies in symptom-free DCM relatives supports an autoimmune component in a subset of DCM cases.
- These autoantibodies may serve as early biomarkers for DCM risk and are associated with subclinical cardiac dysfunction.
Abstract:
Organ-specific antibodies are found in patients with autoimmune disease and their symptom-free relatives many years before clinical onset. Organ-specific cardiac antibodies can be found in patients with dilated cardiomyopathy (DCM) and their relatives, which supports the idea that DCM is an autoimmune disease. We did non-invasive cardiological assessment and antibody screening in 342 symptom-free relatives (170 male, 172 female, mean [SD] age 31 [16] years). 177 relatives were from 33 families with more than 1 affected individual (familial DCM) and 165 relatives from 31 families with only 1 affected member (non-familial DCM). The frequency of cardiac antibodies was higher among relatives of DCM patients than in controls (20% vs 3.5%, p = 0.0001). In 37 (58%) of the families studied, cardiac antibodies were found in the proband and/or in at least 1 family member and were more common in familial than in non-familial DCM (24% vs 15%, p = 0.036). Antibody-positive relatives were younger (26 [15] vs 33 [17] years, p = 0.01) and had a larger mean echocardiographic left ventricular end-systolic dimension (35 [6] vs 32 [6], p = 0.01 mm) and reduced percentage fractional shortening compared with antibody-negative relatives (31 [6] vs 34 [6], p = 0.008). Presence of cardiac-specific autoantibodies in symptom-free DCM relatives provides evidence of autoimmunity in a subset of our patients (58%), including familial and non-familial forms of DCM. These antibodies are associated with mild left ventricular systolic dysfunction on echocardiography and may be early markers for relatives at risk of DCM.