Non-Ischemic Cardiomyopathy Causes and Characteristics

Etiological Categories

• The American College of Radiology notes that alcohol-induced cardiomyopathy is common in men aged 30-55 years with heavy drinking history and probable genetic susceptibility 1, 2
• Chemotherapeutic agents, including anthracyclines, tyrosine kinase inhibitors, trastuzumab, and interferons, can cause cardiomyopathy 1
• Recreational drugs, such as cocaine and methamphetamine, can also lead to cardiomyopathy 3
• Muscular dystrophies can produce dilated cardiomyopathy presenting with heart failure, arrhythmias, or sudden death 1
• A 3-generation family history is recommended when assessing cardiomyopathy causes, as suggested by the American Heart Association 4

Inflammatory/Infectious Causes

• Viral myocarditis accounts for up to 75% of patients presenting with myocardial infarction with non-obstructive coronary arteries (MINOCA) 5
• Bacterial, fungal, or tuberculosis infections can also cause cardiomyopathy 5
• Chagas disease, caused by Trypanosoma cruzi, is endemic in Central and South America and can lead to cardiomyopathy 5
• HIV-associated cardiomyopathy occurs in approximately 8% of asymptomatic HIV-positive individuals 5

Metabolic/Endocrine Causes

• Thyroid disorders, acromegaly, and pheochromocytoma can cause cardiomyopathy 4
• Diabetes mellitus and obesity are also associated with an increased risk of cardiomyopathy 4
• Hemochromatosis and other metabolic storage diseases can lead to cardiomyopathy 3, 4

Clinical Entities

• Peripartum cardiomyopathy occurs in late pregnancy or within 5 months postpartum, with an incidence of 1 in 2,500-4,000 births in the United States 1
• Stress-induced (Takotsubo) cardiomyopathy is characterized by transient left ventricular systolic dysfunction, often triggered by emotional or physical stressors 1, 6
• Left ventricular non-compaction is characterized by prominent trabeculations due to persistent embryonic sinusoids, leading to left ventricular failure, thromboembolism, and arrhythmias 1

Diagnostic Considerations

• Echocardiography typically shows dilated ventricle and global systolic dysfunction in dilated cardiomyopathy, according to the American College of Radiology 1
• Endomyocardial biopsy may be necessary in certain cases, particularly to exclude myocarditis 1

Clinical Pitfalls and Caveats

• Approximately 50% of patients with heart failure and reduced ejection fraction have normal or near-normal coronary arteries on angiography, as noted by the American Heart Association 3
• Incidental coronary artery disease can be found in 10% of patients with stress-induced cardiomyopathy, complicating diagnosis 1

Non-Ischemic Cardiomyopathy Causes and Diagnostic Considerations

Overview of Non-Ischemic Cardiomyopathy

• Non-ischemic cardiomyopathy encompasses a diverse spectrum of myocardial disorders affecting patients without obstructive coronary artery disease, with approximately 50% of heart failure patients with reduced ejection fraction having normal or near-normal coronary arteries, as stated by the American Heart Association 7
• Most cases are idiopathic, but systematic evaluation can identify specific etiologies in many patients, according to the American College of Cardiology 7

Diagnostic Approach and Considerations

• Endomyocardial biopsy is not indicated in routine evaluation of cardiomyopathy, as most patients show nonspecific changes, and the risk of serious complication is less than 1% in experienced centers, as recommended by the American Heart Association 7
• Coronary angiography appears reasonable in young patients to exclude congenital coronary anomalies, and only coronary arteriography can reliably demonstrate or exclude obstructed coronary vessels, as suggested by the American College of Cardiology 7
• Perfusion deficits and segmental wall-motion abnormalities can occur in nonischemic cardiomyopathy, mimicking ischemic disease on noninvasive testing, highlighting the importance of careful diagnosis, as noted by the American Heart Association 7

Metabolic and Endocrine Causes

• Thyroid disorders, both hyperthyroidism and hypothyroidism, can cause or contribute to heart failure, requiring thyroid-stimulating hormone measurement in all patients, as recommended by the Endocrine Society 7
• Diabetes mellitus and obesity are associated with increased cardiomyopathy risk, emphasizing the need for careful management of these conditions, as stated by the American Diabetes Association 7
• Hemochromatosis should be screened with fasting transferrin saturation, as mutated alleles are common in Northern European descent, according to the American College of Medical Genetics 7

Autoimmune and Inflammatory Disorders

• Sarcoidosis can cause cardiomyopathy, though characteristic changes are often missed on histological evaluation, highlighting the need for careful diagnosis, as noted by the American Lung Association 7

Cited Evidence for Non‑Ischemic Dilated Cardiomyopathy Etiologies

Genetic and Familial Causes

• Inherited muscular dystrophies are recognized contributors to dilated cardiomyopathy, commonly manifesting as heart failure, arrhythmias, or sudden cardiac death in affected individuals. 8

Peripartum Cardiomyopathy

• The incidence of peripartum cardiomyopathy in the United States is approximately 1 case per 2,500–4,000 births. 9
• Identified risk factors include multiparity, maternal age > 30 years, obesity, non‑white ethnicity, low socioeconomic status, prolonged tocolytic therapy, hypertension, pre‑eclampsia, and cocaine use. 8
• Endomyocardial biopsy may be required in selected patients to exclude underlying myocarditis when evaluating peripartum cardiomyopathy. 8

Stress‑Induced (Takotsubo) Cardiomyopathy

• Stress‑induced cardiomyopathy presents with acute, usually reversible left‑ventricular systolic dysfunction that is precipitated by intense emotional or physical stress and is mediated by catecholamine excess. 9
• Clinically, it mimics acute myocardial infarction, producing chest pain, ST‑segment elevation on electrocardiogram, and elevated cardiac enzymes. 9
• Diagnosis relies on the Mayo Clinic or InterTAK diagnostic criteria, which incorporate imaging findings and the absence of obstructive coronary disease. 9
• Incidental coronary artery disease is identified in roughly 10 % of patients with stress‑induced cardiomyopathy, potentially complicating the diagnostic process. 8

Cirrhosis‑Related Cardiomyopathy

• Patients with chronic liver disease may develop a distinct cardiomyopathy that occurs independently of alcohol exposure. 8

Left‑Ventricular Non‑Compaction

• Left‑ventricular non‑compaction is characterized by prominent trabeculations resulting from persistence of embryonic myocardial sinusoids; it predisposes to left‑ventricular failure, thromboembolic events, and arrhythmias. 8