In another recent study, the expression of TIMP-1 was high in patients with persistent AF and chronic AF but not in those with paroxysmal AF [25], and elsewhere it was found that there was no significant difference in the plasma levels of TIMP-1 in patients with paroxysmal AF or those with persistent AF [24], which differed slightly from the findings of the present study. The gene discussed is TIMP1; the disease is Paroxysmal atrial fibrillation.