Patients with AF, independently from the arrhythmia duration (paroxysmal or persistent AF), were characterized by a higher level of TIMP-1 in comparison with individuals with the sinus rhythm (SR), Moreover, patients with persistent AF had lower levels of MMP-1 but increased levels of TIMP-1 in comparison with patients with paroxysmal AF [48]. The gene discussed is MMP1; the disease is atrial fibrillation.