Cardiac Causes of Systolic Dysfunction
Coronary artery disease producing ischemic cardiomyopathy is the most frequent cardiac cause of left ventricular systolic dysfunction, followed by non-ischemic cardiomyopathies which may be inherited or sporadic. 1
Primary Cardiac Etiologies
Ischemic Causes
- Coronary artery disease/Ischemic cardiomyopathy - This is the dominant cause of systolic dysfunction 1, 2
- Myocardial infarction leading to ventricular remodeling with compensatory dilation and hypertrophy 3
- Regional wall motion abnormalities (hypokinesis, akinesis, dyskinesis) indicating myocardial infarction or ischemia 4
Non-Ischemic Cardiomyopathies
- Dilated cardiomyopathy - characterized by left ventricular dilation with systolic dysfunction 5
- Inflammatory disorders including myocarditis 5
- Toxic cardiomyopathy from medications, alcohol, or illicit drugs 5
- Metabolic disorders - particularly important in children where mitochondrial dysfunction and metabolic abnormalities are causal 5
- Infiltrative diseases 6
- Idiopathic dilated cardiomyopathy 6
Valvular Heart Disease
- Aortic stenosis - degenerative calcific AS is the most common valvular disease co-existing with LV systolic dysfunction 7
- Myocyte apoptosis and myocardial fibrosis drive the transition from compensated LV hypertrophy to heart failure with reduced ejection fraction 7
- Mitral regurgitation - can be either a cause or consequence of systolic dysfunction 4
Other Cardiac Causes
- Hypertrophic cardiomyopathy 4
- Arrhythmogenic right ventricular cardiomyopathy 4
- Congenital heart disease 4
Diagnostic Approach
Measure ejection fraction in all patients with suspected heart failure to confirm systolic dysfunction, defined as EF <40-50%. 4, 1
Key Echocardiographic Findings Indicating Systolic Dysfunction 4:
- LV ejection fraction <50% (global systolic dysfunction)
- LV fractional shortening <25% (radial systolic dysfunction)
- Regional wall motion abnormalities (suggests ischemic etiology)
- LV end-diastolic diameter ≥60 mm or >32 mm/m²
- LV end-systolic diameter >45 mm or >25 mm/m²
- LV outflow tract velocity time integral <15 cm (reduced stroke volume)
Distinguishing Ischemic from Non-Ischemic Etiology
After confirming systolic dysfunction (EF ≤40%), determine if there is a reversible cause, particularly ischemic or valvular heart disease 1. This distinction is critical as it determines whether revascularization or valve intervention should be considered alongside medical therapy.
Clinical Implications
Both ischemic and non-ischemic dilated cardiomyopathies produce similar heart failure symptoms, frequent hospitalizations, and increased risk of premature death 1. Progressive pump failure and malignant arrhythmias are the most frequent causes of death, with thromboembolic events (particularly strokes) complicating the clinical course 1.