Recovery of complete left bundle branch block in a dilated cardiomyopathy patient after treatment with sacubitril/valsartan: A case report

Rationale:The treatment of dilated cardiomyopathy (DCM) has recently been greatly improved, especially with the widespread use of sacubitril/valsartan (ARNI) combination therapy. We know that ARNI-like drugs can significantly improve the symptoms of heart failure with reducing ejection fraction. However, clinical studies evaluating the safety and efficacy of ARNI in DCM-associated arrhythmia are limited, and whether individuals with arrhythmia would benefit from ARNI remains controversial. In this case, we report a patient with complete left bundle branch block (CLBBB) associated with DCM whose CLBBB returned to normal after treatment with ARNI.Patient concerns:A 38-year-old man was admitted to the hospital for 20 days for idiopathic paroxysmal dyspnea. He presented with exacerbated dyspnea symptoms at night, accompanied by cough and sputum.Diagnosis:Physical examination revealed a grade 4/6 systolic murmur could be heard in the apical area of the heart and mild edema was present in both lower limbs. Laboratory examination found that the B-type natriuretic peptide was significantly increased. Echocardiography indicated left atrial internal diameter, right ventricular internal diameter, and left ventricular diastolic diameter were enlarged and ejection fraction was significantly decreased. Besides, the pulsation of the wall was diffusely attenuated. Electrocardiogram was suggestive of tachycardia and CLBBB. A diagnosis of DCM with CLBBB was considered based on a comprehensive evaluation of the physical examination, laboratory examination, echocardiography and electrocardiogram.Interventions:The patient was treated with ARNI at a dose of 50 mg (twice a day) at first, gradually increasing to the target dose (200 mg, twice a day) in the following 9 months as shown in Table ​Table1,1, along with metoprolol 25 mg (once a day [qd]), diuretics 20 mg (qd), and aldosterone 20 mg (qd).Table 1Specific medications used in treatment.

Month(s) and dates after discharge	Morning (ARNI)	Night (ARNI)	Metoprolol 23.75 mg QD; diuretics (furosemide) 20 mg QD; aldosterone 20 mg QD
Month 1 (28/02/20–27/03/20)	50 mg	50 mg
Month 2 (27/03/20–26/04/20)	100 mg	50 mg
Month 3–4 (26/04/20–28/06/20)	100 mg	100 mg
Months 5–7 (28/05/20–29/08/20)	150 mg	100 mg
Months 8–11 (29/08/20–13/11/20)	150 mg	150 mg
Month 11–present (13/11/20–)	200 mg	200 mg

Open in a separate windowARNI = sacubitril/valsartan, QD = once a day.Outcomes:After treatment with ARNI during the 9-month follow-up, the patient’s symptoms improved, and CLBBB returned to normal.Lessons:Clinical studies evaluating the safety and efficacy of ARNI in DCM-associated arrhythmia are limited, and whether individuals with arrhythmia would benefit from ARNI remains controversial. This report will help to instruct the clinical treatment of DCM patients with CLBBB and the potential application of ARNI.