Dual atrioventricular nodal non‑reentrant tachycardia (DAVNNT) is a rarely diagnosed, sustained supraventricular arrhythmia. We report the case of a 39‑year‑old female with drug‑resistant, irregular, narrow QRS complex tachycardia which gradually led to tachycardia‑in duced cardiomyopathy. Previously, this arrhythmia was recognized as atrial fibrillation, with several unsuccessful attempts at pulmonary vein isolation. Only after the correct diagnosis of DAVNNT was established, successful radiofrequency ablation of the slow pathway in the atrioventricular node was performed, with complete cure of the arrhythmia