Atrial Fibrillation as a Prognostic Indicator in Patients With Orthostatic Hypotension: Nationwide Inpatient Sample Analysis

Background: Orthostatic hypotension and atrial fibrillation have common etiology and a bidirectional relationship with several cardiovascular conditions. Despite both conditions being highly prevalent in hospitalized patients, prior research has primarily evaluated adverse outcomes due to orthostatic hypotension and atrial fibrillation independent of each other. In this study, we aim to assess if the presence of atrial fibrillation exacerbates in-hospital outcomes of patients with orthostatic hypotension. Methods: Adult patients hospitalized in 2019 with a primary diagnosis of orthostatic hypotension with or without pre-existing atrial fibrillation were identified using the International Classification of Diseases, Tenth Revision (ICD-10) code. The primary outcome of interest was in-patient mortality and cardiac arrest. Secondary outcomes of interest were the length of stay and total hospital charges. Adjusted and unadjusted analysis was performed on appropriate variables of interest. Results: Among 10,630 hospitalizations with orthostatic hypotension, 2,987 (median (interquartile range (IQR)) age: 78.5 (68.5 - 88.5) years; 1,197 women (40.1%)) comprised the atrial fibrillation cohort. Mean Charlson comorbidity index was noted to be significantly higher in orthostatic hypotension and atrial fibrillation patients (mean (standard deviation (SD)): 3.1 (2.1) vs. 2.5 (2.1), P < 0.001).Compared to orthostatic hypotension patients without atrial fibrillation, the prevalence of congestive heart failure (1,263 (42.3%) vs. 1,367 (17.9%)), coronary artery disease (1,432 (47.9%) vs. 2,481 (32.5%)), history of percutaneous coronary intervention or graft (443 (14.83%) vs. 860 (11.3%)), chronic obstructive pulmonary disease (644 (21.6%) vs. 1,131 (14.8%)) , chronic kidney disease (1,182 (39.6%) vs. 2,216 (29.0%)), and hyperlipidemia (1,828 (61.2%) vs. 4,087 (53.5%); all P < 0.05), were significantly higher in orthostatic hypotension patients with atrial fibrillation. Following multivariable analysis of orthostatic hypotension patients, atrial fibrillation was associated with 5.0 times greater odds for cardiac arrest (adjusted odds ratio (aOR) = 5.0 (95% confidence interval (CI): 1.4 - 18.2), P = 0.014), without increased risk of in-hospital mortality (aOR = 2.1 (95% CI: 0.9 - 5.0), P = 0.090). Conclusions: Atrial fibrillation is an independent predictor for cardiac arrest but not in-hospital mortality in patients with orthostatic hypotension. The short- and long-term prognostic value of atrial fibrillation in orthostatic hypotension patients must be confirmed in future prospective trials to improve patient outcomes.