The impact of atrial fibrillation and atrial tachycardias (AF/AT), and their optimal treatment strategy in PH patients is still being discussed. The goal of this study was to evaluate the effect of AF/AT termination on the hemodynamic parameters in PH patients. We compared patients with pre-capillary pulmonary hypertension (PH group), left ventricular heart failure (LV-HF group), and a Control group. A repeated right heart catheterization was performed during the catheter ablation (CA) procedure. The first measurement was done in arrhythmia, the second after the sinus rhythm (SR) was restored. High frequency atrial stimulation was used to simulate AT in patients without arrhythmia presence at the time of the CA. The variation of pressure parameters in PH patients did not differ significantly from the Controls. There was a significant increase in the right ventricle pressure after the SR restoration in the LV-HF group compared to the Controls and PH group (+4 vs. -2 vs. -3 mmHg, p<0.05). The cardiac index (CI) variation was not significant when compared between the study groups. An increase of the CI after the SR restoration was found in those patients with AF (+0.31 l/min/m² [IQR 0.18; 0.58]) in contrast to those patients with organized AT/high frequency atrial stimulation (-0.09 l/min/m², [IQR - 0.45; 0.19]). This difference was statistically significant (p<0.05). The acute hemodynamic response to arrhythmia termination was not significantly different in the PH patients when compared to the Controls. In contrast to AT/high frequency stimulation, the restoration of SR in AF patients leads to an increased CI, irrespective of the presence or absence of PH.