Abstract Body (Do not enter title and authors here): Introduction
Hyponatremia is a common electrolyte abnormality that has been associated with poor outcomes in several conditions including acute myocardial infarction (AMI). However, those studies were performed in the era before percutaneous coronary intervention (PCI), focused mostly on ST-elevation myocardial infarction (STEMI), and sodium levels up to 72 h of admission.

Aim: The purpose of this study was to identify the prognostic importance of hyponatremia in patients with acute myocardial infarction.

Methods
We performed a cross sectional and retrospective analysis of 100 patients with a diagnosis of non-ST-elevation myocardial infarction (NSTEMI) and STEMI presenting at PSH, Vadodara, Gujarat, India from January 2022 to May 2024. Our independent variables were sodium levels on the day of admission. Dependent variables were in-hospital mortality, 30-day mortality, length of hospital stay, intensive care admission, new heart failure diagnosis, and ejection fraction. Infarct size was determined by echocardiographic examination that was performed on admission, day 2 or 3 of hospitalization

Results
Hyponatremia, defined as a plasma sodium level <135 mmol/L (<135 mEq/L). 32% of patients had hyponatremia up to 7 days of admission. Intensive care admission was higher in patients with hyponatremia up to7 days (70% vs 383%), they had worse 30-day mortality (15% vs to 3%), in hospital mortality (12% vs 2%), and new heart failure diagnosis (32% vs 16%). Hyponatremia on admission was associated with in-hospital mortality (15% vs 4%), 30-day mortality (19% vs 6 %).

Conclusions
This study suggests that hyponatremia on admission and at any point during the first seven days of hospitalization are associated with in-hospital and 30-day mortality and prognosis worsens with the severity of hyponatremia. Further studies are required to determine if plasma sodium levels may serve as a simple marker to identify patients at high risk.