Abstract Background Atrial Fibrillation (AF) poses a significant burden on the American Healthcare system. Heart failure and AF commonly coexist in patients. Elevated left ventricular and atrial pressures result in progressive left atrial dilation and remodeling which in turn predisposes to the generation of AF. Many of these patients develop pulmonary hypertension (PHT) due to the remodeling and elevated left-sided pressures. Cardioversion (CV) for non-valvular atrial fibrillation (AF) is commonplace for patients during their initial presentation. Since many who undergo CV for AF could have PHT, we aimed to assess the periprocedural outcomes in this population. Methods We utilized the National Inpatient Sample from 2016-2019 to identify roughly 330,820 hospitalized adults who had CV for AF. These hospitalizations were further stratified based on the presence of PHT. A multivariate regression model was used to adjust for confounders and analyze the variables. Results Of those who underwent CV for AF, 45,345 (13.7%) had PHT. In-hospital mortality was interestingly lower in those with PHT (9.6% vs 10.37%; p<0.001). Figure 1 shows the Forrest plot for multivariate analysis of in-hospital outcomes when adjusted for patient demographics, comorbidities, and hospital characteristics. When adjusted similarly, patients who underwent CV for AF and PHT had longer length of stay (LOS) by 2.11 days (p<0.001) and had additional hospital costs (HC) of $29,470 (p<0.001). Conclusion In this study, patients who underwent CV for AF with co-existing PHT had significantly worse outcomes in terms of LOS, HC, pulmonary embolism, atrial flutter, VT, SVT, AKI, and intubation. Of note, they interestingly had better outcomes in terms of in-hospital mortality, respiratory failure, and strokes. Returning the patient to sinus rhythm likely improved the left heart hemodynamics reducing post capillary pulmonary hypertension explaining the reduced mortality rate in this population. One major limitation of our study is the lack of outpatient follow up and the inability to differentiate between the different groups of PHT. Since several outcomes are worse in the setting of PHT, potential strategies for aggressive rate and volume control for those in AF should be pursued to avoid negative cardiac remodeling that would predispose to the development of PHT. AF patients with co-existing PHT should be aggressively monitored during hospitalizations as they have the potential to have worse outcomes.