Prognostic Impact of Admission Acidosis on In-Hospital Outcomes in Acute Decompensated Heart Failure: A Prospective Multicenter Cohort Study from Pakistan

Abstract

Objectives: To determine the frequency of acidosis at hospital admission and evaluate its impact on in-hospital outcomes among patients admitted with acute decompensated heart failure. Methodology: This prospective cohort study was conducted at four satellite centers of the Sindh Institute of Cardiovascular Diseases, Pakistan. A total of 370 adult patients admitted with acute decompensated heart failure were enrolled. Arterial blood gas analysis was performed within 6 hours of admission, and patients were categorized as acidotic (pH ≤ 7.35) or non-acidotic (pH > 7.35). Primary outcome was in-hospital mortality, while secondary outcomes included mechanical ventilation requirement and length of hospital stay. Multivariate logistic regression was used to identify independent predictors of mortality. Results: Acidosis was present in 20% (74/370) of patients at admission. Acidotic patients had significantly lower mean left ventricular ejection fraction and higher NT-proBNP, serum creatinine, and lactate levels. In-hospital mortality was markedly higher in the acidotic group (28.4% vs. 10.6%, p < 0.001). Acidotic patients also required more frequent mechanical ventilation and had prolonged hospital stays. On multivariate analysis, acidosis emerged as the strongest independent predictor of in-hospital mortality (adjusted OR 2.87, 95% CI 1.41–5.81, p = 0.003). Conclusion: Acidosis at admission is common in patients with acute decompensated heart failure and is strongly associated with adverse in-hospital outcomes. Early assessment of arterial blood gases may facilitate timely risk stratification and guide escalation of care in this high-risk population.