The present study included symptomatic HF patients with DCM, New York Heart Association (NYHA) functional class III-IV, left ventricular (LV) ejection fraction (EF) <30%, refractory to optimal evidence-based guidelines-recommended HF therapy including angiotensin-converting enzyme inhibitor (ACEI) or angiotensin receptor blocker (ARB), beta blocker, diuretics, mineralocorticoid receptor antagonist (MRA), ivabradine, or digoxin treatment for at least 6 months. Coronary artery disease was excluded by coronary angiography. Patients with HF due to known origins such as primary valvular disease, congenital heart disease, or other cardiomyopathies and also those with severe chronic obstructive pulmonary disease, severe chronic kidney or liver disease, connective tissue disease, active infectious disease, chronic alcoholism, or malignancy were excluded from the study.
A total of 38 HF patients with DCM were screened for AABs directed against beta1-AR and M2-muscarinic receptors. Notably, 17 patients (44%) were positive for cardiac AABs, in which 16 patients have had AABs against beta1-AR and 3 patients have had AABs for M2-muscarinic receptors (2 of them were also positive for beta1-AR AAB). Nine patients with cardiac AABs who gave written informed consent were included in the study and underwent IA therapy (Figure 1). This study has been conducted between 2014 and 2018 in a university hospital, outpatient Heart Failure Unit with the capability of implantation of cardiac resynchronization therapy or implantable cardiac defibrillator and short-term mechanical circulatory support, which is affiliated with an institution with the availability of long-term ventricular assist devices or heart transplantation. The study protocol was approved by the ethics committee, and the study was performed in accordance with the guidelines of the Declaration of Helsinki.