Demographic, clinical, and laboratory factors associated with one-year readmission after percutaneous coronary intervention: a retrospective analysis

Percutaneous coronary intervention (PCI) is a standard treatment for coronary artery disease. However, hospital readmission following PCI is a significant metric of care quality and patient outcomes. Given the need to understand readmission patterns in limited-resource settings, this study aimed to explore the rate of readmission and potential associated factors among PCI patients. This retrospective cohort study included adult patients with ACS who underwent emergency PCI at a tertiary cardiovascular center in Rasht, Iran, between March and September 2019 and survived to discharge. Baseline demographic, clinical, and laboratory variables were extracted from electronic medical records. The primary outcome was 1-year unplanned cardiac-related readmission to the index hospital, determined using electronic records and structured telephone follow-up. Associations between baseline variables and readmission were assessed using Firth’s penalized logistic regression because of the small number of outcome events. Model performance was evaluated by AUC and bootstrap internal validation. Of the 430 patients included, 31 (7.2%) experienced hospital readmission. Readmitted patients were significantly younger ( \(\:56.68±\:8.13\) vs. \(\:60.22±\:11.40\) years, \(\:p=0.029\) ) and had a higher prevalence of prior elective ( \(\:9.7%\) vs. \(\:1.5%\) , \(\:p=0.021\) ) and emergency angioplasty ( \(\:45.2%\) vs. \(\:3.8%\) , \(\:p<0.001\) ), alongside lower serum sodium levels ( \(\:p=0.013\) ). In multivariable Firth penalized logistic regression, independent predictors of readmission were prior emergency angioplasty ( \(\:OR=23.101,95%\:CI:8.973\--62.991,p<0.001\) ) and prior elective angioplasty ( \(\:OR=10.202,95%\:CI:1.824\--48.778,p=0.010\) ). Conversely, higher serum sodium concentration was independently associated with a reduced risk of readmission ( \(\:OR=0.830,95%\:CI:0.710\--0.967,p=0.017\) ). The model demonstrated good discriminative performance ( \(\:AUC=0.84,95%\:CI:0.77\--0.91\) ) and adequate calibration ( \(\:p=0.62\) ). Prior history of coronary angioplasty, particularly emergency procedures—and lower baseline serum sodium are strong independent determinants of hospital readmission. These indicators can assist in risk-stratifying patients for targeted post-discharge monitoring and transitional care interventions.