FIELD : medicine.SUBSTANCE : invention relates to medicine, namely cardiology, and is a method for predicting the development of left atrial dilatation in patients with cardiac arrhythmias, characterized by the fact that patients are genotyped, the rs6684209 polymorphism of CASQ2 calsequestrin gene is determined, and a high risk of developing left atrial dilatation is predicted when detecting a carrier of SS genotype.EFFECT : invention provides for the identification of patients with a high risk of left atrial dilatation and progression of paroxysmal and persistent atrial fibrillation and sick sinus syndrome.1 cl, 2 ex