Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (55 page)

   
Inherited syndromes
: DCM can be associated with various inherited neuromuscular diseases in addition to genetically determined HF as noted above. These include hereditary hemochromatosis, sideroblastic anemia, myotonic dystrophy, and muscular dystrophies.

   
Left ventricular noncompaction
: A congenital cardiomyopathy (0.05%) where the apical portion of the ventricle with deep intratrabecular recesses that occur in embryogenesis. Presentation usually includes DCM with heart failure, but thromboemboli, arrhythmias, and sudden cardiac death may occur. Diagnosis is made with echo, with genetic testing available for some recognized etiologies (X-linked).

   
Toxins/medications
: Exposure to alcohol (80 g/day in men and 40 g/day in women over a number of years), cocaine, cobalt, and arsenic and deficiencies of selenium and thiamine may cause DCM. Common medications include antiretrovirals, chloroquine, and anthracyclines. A cumulative dose >450 mg/m
²
of anthracycline greatly increases the chance of cardiotoxicity. While diagnosis is definitely made with biopsy, often history alone is sufficient for diagnosis.

   
Valvular
: Diagnosed by exam and echocardiography. Due to valvular abnormalities, systolic dysfunction occurs out of proportion to increases in wall stress. Most commonly seen in left-sided regurgitant lesions (mitral regurgitation, aortic regurgitation >aortic stenosis).

   
Autoimmune
: Autoimmunity likely plays a role in myocarditis but can also result in a DCM from cardiac antigens of troponin, myosin (α,β chains), and beta-1 adrenoreceptor. Presence of antiheart antibodies is increased in families with DCM, but at present, no recommendations exist for routine screening. Systemic lupus erythematosus commonly involves the heart, but with varied clinical presentation ranging from coronary disease/vasculitis to cardiomyopathy. Involvement is almost uniformly secondary. Celiac disease, however, may not present with classic GI symptoms, but rather iron deficiency with DCM only. Endomysial antibody screening is reasonable in such patients.

HEART FAILURE WITH PRESERVED EJECTION FRACTION (HF
_P
EF)

   Definition

   Clinical history, presentation, and physical findings are essentially indistinguishable from HF with reduced ejection fraction.

   As many as half of all patients presenting with HF will have normal/near normal ejection fraction.

   Diastolic HF is the predominant etiology of HFpEF, which also encompasses a mixed group of clinical syndromes that includes cardiac infiltrative disease, valvular heart disease, right ventricular cardiomyopathy, and hypertrophic cardiomyopathy.

   Who Should Be Suspected?

   Risk factors for HFpEF due to diastolic dysfunction include older age (>50% of HF patients over 70 years), female (2:1), hypertension, and diabetes mellitus.