Circulation Cardiovascular Case Series

A 25-year-old white woman was referred to the outpatient cardiology clinic at our institution for a second opinion regarding a newly diagnosed cardiomyopathy. She was in a normal state of excellent health, without a significant past medical history, when she began to develop exertional fatigue, dyspnea, orthopnea, and paroxysmal nocturnal dyspnea. Her primary care provider diagnosed her with pneumonia. The following day she developed severe, cramping pain in her right leg associated with pallor. She was hospitalized and diagnosed with an arterial embolization of her right femoral artery. She was managed with tissue plasminogen activator and thrombectomy, resulting in the reconstitution of her right lower extremity arterial supply. While hospitalized, the patient underwent a transthoracic echocardiogram that demonstrated a mildly dilated left ventricle (LV) with an ejection fraction (EF) of ≈30%, a negative microcavitation study, and no evidence of LV thrombus. N-terminal probrain natriuretic peptide was 2296 pg/mL (normal <190 pg/mL). After a standard medical regimen for heart failure, warfarin was initiated because of the arterial thromboembolic event. Tests for Factor V Leiden mutation, protein C/S deficiency, and prothrombin gene mutation were negative. After hospital discharge she continued to experience cardiovascular symptoms. She could walk only 1 flight of stairs without shortness of breath. She had ongoing fatigue and lost ≈10 pounds. She had no history of tobacco use and consumed only minimal alcohol. Her family history was remarkable for aortic dissection in her father at 49 years of age but otherwise was without cardiovascular disease. Physical examination was notable for a heart rate of 97, blood pressure of 100/70, and body mass index of 18.1. Her jugular venous pressure was estimated at 10 to 12 cm of water. She had an audible S3 gallop without murmurs and no lower extremity edema. ECG showed normal sinus rhythm with biatrial enlargement and a QRS duration of 84 ms. Dr Patel: The patient is presenting with New York Heart Association functional class II to III symptoms and echocardiographic evidence of a dilated cardiomyopathy. Although she did not undergo an ischemic evaluation on initial presentation, she has no obvious risk factors for coronary artery disease, so this likely represents a nonischemic cardiomyopathy. The differential diagnosis is broad; for example, in a review of ≈1200 patients with initially unexplained cardiomyopathy who underwent endomyocardial biopsy, half had no cause identified (ie, idiopathic cardiomyopathy) during follow-up. Those with identifiable causes had myocarditis (9%), ischemic heart disease (7%), infiltrative disease (5%), hypertension (4%), connective tissue disease (3%), and substance abuse (3%). Among patients with idiopathic dilated cardiomyopathy, clinical screening of family members can diagnose a familial cause in ≤50%. The arterial thromboembolic event may be unrelated to her cardiac issues; however, heart failure with systolic dysfunction increases the risk of thromboembolism and a LV thrombus or predisposing atrial arrhythmia should be ruled out. While attempting to identify an underlying, possibly reversible, etiology, it is important to initiate optimal medical therapy for heart failure as was done in this case. The next diagnostic step could include cardiac magnetic resonance (CMR). CMR would allow for better characterization of the myocardium and would rule out ischemic disease. In addition to detailed morphological assessment (mass, size, function), gadolinium contrast enhancement techniques can identify and characterize areas of myocardial scar and fibrosis, the pattern of which may suggest specific etiologies.