The electrophysiological mechanisms of atrial arrhythmias in patients with atrial septal communication (ASD or PFO) may involve increased P-wave dispersion (Pdysp). With the advancement of medicine, therapeutic goals are to improve a patient's functioning in society, fulfillment of social roles, and the restoration of well-being. The aim of the study was to: assess P-wave dispersion (Pdysp), the prevalence of arrhythmia and assess QoL in patients before and after ASD or PFO closure. The study group included 129 patients (70 female), with a mean age of 44.5±13.4 years, scheduled for percutaneous closure of ASD (n= 56) or PFO (n=73). We performed 12-lead electrocardiograms, echocardiograms, and 24-h Holter electrocardiograms and a clinical assessment, conducted an SF-36 questionnaire. Pdysp was predicted by right ventricular outflow tract (RVOT) proximal diameter, left atrial area, ASD, smoking, and paroxysmal dyspnea. In patients with ASD QoL improvement was predicted by higher baseline tricuspid annular plane systolic excursion (TAPSE) and right ventricular longitudinal dimension. In patients with PFO QoL improvement was predicted by higher TAPSE, lack of arterial hypertension, and usage of ACEI. Percutaneous closure of (ASD or PFO) was associated with a reduction of Pdysp. Improvement of QoL was predicted by echocardiographic and clinical parameters.