A 54-year-old woman presents to the emergency department with approximately 2 days of increasing shortness of breath (SOB) and palpitations. She was diagnosed with a nonischemic cardiomyopathy (NICM) approximately 6 years earlier and has been managed with enalapril 10 mg twice daily, carvedilol 12.5 mg twice daily, and furosemide 40 mg daily.

On arrival, she appears comfortable at rest but anxious. Her heart rate (HR) is 124 bpm and irregular, blood pressure (BP) is 131/84 mm Hg, and oxygen saturation is 97% on room air. She weighs 64 kg (141 lbs) and is 160 cm (5′3″) tall (body mass index 25 kg/m²). On examination, she is warm. Cardiac examination reveals: tachycardia with irregularly irregular rate and rhythm; S₁ and S₂; grade 2/6 systolic murmur at the apex; clear lungs; abdomen flat, soft, and nontender; and cool extremities with 2+ pulses in the groin and feet. She has 1+ to 2+ peripheral edema.

Her medical history is significant for an NICM that was diagnosed 4 years earlier when she presented with cough and fever and was diagnosed with a lobar pneumonia. Her left ventricular ejection fraction (LVEF) was 40% with mild mitral regurgitation (MR). A coronary angiogram had unremarkable findings. Thyroid and iron study findings were within the reference ranges.

Her paternal uncle died of heart failure (HF) at 49 years of age and a cousin has HF. Her paternal grandmother died at 36 years of age but the details are not known. The patient has two children, 22 and 25 years of age, both of whom have no known medical conditions.

Laboratory studies are obtained (Table 1).

Table 1

aPTT = activated partial thromboplastin time; BUN = blood urea nitrogen; Cr = creatinine; hs-TnI = high-sensitivity troponin I; INR = international normalized ratio; NT-proBNP = N-terminal pro–B-type natriuretic peptide; PT = prothrombin time; TSH =; WBC = white blood cell count.

An echocardiogram has findings of moderately dilated left ventricle (LV) with LVEF 10% with global hypokinesis, right ventricle (RV) top-normal in size with moderate to severe decreased systolic function, severely dilated left atrium (LA) and moderately dilated right atrium (RA), restricted mitral valve leaflet mobility with moderate MR, and mild tricuspid regurgitation (TR) with pulmonary artery systolic pressure (PASP) 38 mm Hg.

She undergoes an emergent transesophageal echocardiogram, which reveals no evidence of LA thrombus. She then undergoes a successful electrical cardioversion that restores normal sinus rhythm (NSR). She improves clinically and has a brisk diuresis to intravenous diuretics.

Over the following 4 days, her medications are adjusted to include sacubitril/valsartan 49/51 mg twice daily, carvedilol 12.5 mg twice daily, spironolactone 25 mg daily, amiodarone 200 mg daily, apixaban 5 mg twice daily, and furosemide 40 mg daily. She is discharged home.

She returns to the office 1 week later. She reports that she is comfortable at rest but has noted significant dyspnea on exertion around her home and with walking up approximately half a flight of stairs. An electrocardiogram (ECG) has findings of NSR. Her BP is 116/74 mm Hg and HR is 86 bpm and regular. Her dosage of carvedilol is increased to 25 mg twice daily and empagliflozin 10 mg is added to her regimen.

She returns to the office 2 weeks later and notes that her symptoms are modestly improved but she continues to have dyspnea with walking up inclines or stairs. Her BP is 108/70 mm Hg and HR is 74 bpm. Her weight has been stable since discharge from the hospital. Her electrolyte levels and kidney function values are stable.

She returns to the office 3 months later and undergoes an echocardiogram, which has findings of LVEF 25% with mild to moderate MR, RV top-normal in size with mild to moderate decreased systolic function, moderately dilated LA and RA, and mild TR with PASP 28 mm Hg. She reports that she continues to experience SOB with many activities around her home, including carrying laundry, vacuuming, climbing stairs, and preparing meals. Her medications include sacubitril/valsartan 97/103 mg twice daily, carvedilol 25 mg twice daily, spironolactone 25 mg daily, empagliflozin 10 mg daily, amiodarone 100 mg daily, apixaban 5 mg twice daily, and furosemide 40 mg daily. Her BP is 115/74 mm Hg and HR is 74 bpm and regular. Her laboratory study values are stable except for blood urea nitrogen level 28 mg/dL and creatinine level 1.5 mg/dL. Her N-terminal pro–B-type natriuretic peptide level is 208 pg/mL, liver function test values are within the reference ranges, and thyroid-stimulating hormone level is 1.8 mIU/L.

An ECG is obtained (Figure 1).

Figure 1