Ms. AH is a 48-year-old woman who presents with a 3-month history of progressively worsening exertional dyspnea and symmetric bilateral lower extremity edema. She has no history of recent upper respiratory symptoms or chest pain.

She denies any tobacco, alcohol, or recreational drug use. There is no family history of premature CAD or HF.

On exam, her blood pressure is 110/66 mmHg, heart rate is 112 bpm, and respiration rate is 18 breaths/min with oxygen saturation of 98% on ambient room air. She has jugular venous distention of about 12cm H2O, bibasilar crackles, an S3 heart sound, and bilateral lower extremity edema.

Complete blood count, serum electrolytes, kidney function tests, liver chemistry tests, glucose level, iron studies, and lipid levels are unremarkable.

An electrocardiogram shows sinus tachycardia with normal intervals and no conduction delays. A transthoracic echocardiogram demonstrates a left ventricular ejection fraction of 25%, normal right ventricular size and function, and no valvular abnormalities.

Which of the following diagnostic tests has a Class I indication for further evaluation?

A

Cardiac catheterization

B

Referral for genetic counseling

C

Thyroid function studies

D

Cardiac MRI

Explanation 

The correct answer is C – thyroid function studies have a Class 1 indication for the evaluation of HF. 

The common causes of HF include coronary artery disease, hypertension, and valvular heart disease. Other causes may include arrhythmia-associated, toxic, inflammatory, metabolic including both endocrinopathies and nutritional, infiltrative, genetic, stress induced, peripartum, and more. It is important to evaluate for the etiology of a given patient’s heart failure as diagnosis may have implications for treatment, counseling, and family members.

For patients who are diagnosed with HF, laboratory evaluation should include complete blood count, urinalysis, serum electrolytes, blood urea nitrogen, serum creatinine, glucose, lipid profile, liver function tests, iron studies, and thyroid-stimulating hormone to optimize management (Class 1, LOR C-EO). These studies provide important information regarding comorbidities, suitability for and adverse effects of treatments, potential causes or confounders of HF, and severity and prognosis of HF.

HF is often caused by coronary atherosclerosis, and evaluation for ischemic heart disease can help in determining the presence of significant coronary artery disease (CAD). Noninvasive stress imaging with echocardiography or nuclear scintigraphy can be helpful in identifying patients likely to have obstructive CAD. Invasive or computed tomography coronary angiography can detect and characterize the extent of CAD. Therefore, in patients with HF, an evaluation for possible ischemic heart disease can be useful to identify the cause and guide management (Class 2a, LOE B-NR).

Familial cardiomyopathy is increasingly recognized and may be the underlying etiology of patients previously classified as having idiopathic dilated cardiomyopathy. A detailed family history may provide the first clue to a genetic basis. A 3-generation family pedigree obtained by genetic health care professionals improved the rate of detection of a familial process as compared with routine care. Furthermore, a family history of cardiomyopathy, as determined by a 3-generation pedigree analysis, was associated with findings of gadolinium enhancement on cardiac magnetic resonance imaging (MRI) and increased major adverse cardiac events. The possibility of an inherited cardiomyopathy provides the impetus for cascade screening of undiagnosed family members, thereby potentially avoiding preventable adverse events in affected relatives by implementation of GDMT and other management that otherwise would not be initiated. Therefore, in patients with cardiomyopathy, a 3-generation family history should be obtained or updated when assessing the cause of the cardiomyopathy to identify possible inherited disease (Class 1, LOE B-NR). In selecting patients with nonischemic cardiomyopathy, referral for genetic counseling and testing is reasonable to identify conditions that could guide treatment for patients and family members (Class 2a, LOE B-NR).

CMR provides noninvasive characterization of the myocardium that may provide insights into HF cause. Registry data show that CMR findings commonly impact patient care management and provide diagnostic information in patients with suspected myocarditis or cardiomyopathy. However, routine screening with CMR is not recommended. The OUTSMART HF trial recently demonstrated routine cardiac MRI use did not yield more specific HF causes than a selective strategy based on echocardiographic and clinical findings. The guidelines give a Class 2a recommendation for the use of CMR in diagnosis or management in patients with HF or cardiomyopathy (LOE B-NR).  

Main Takeaway

The common causes of HF include ischemic heart disease, hypertension, and valvular heart disease. When a patient presents with new-onset heart failure, a complete initial evaluation including laboratory testing for potentially reversible causes such as thyroid disease, or other endocrine, metabolic, and nutritional causes should be performed.

Guideline Loc.

Section 3.2, 4.1, 4.3, and 4.4

Table 5