This study compared the use and outcomes associated with intravenous diltiazem and/or intravenous digoxin as a primary therapy in patients admitted for treatment of atrial fibrillation. METHODS: A retrospective data base analysis was conducted with data from 7 academic medical centers. The use of intravenous diltiazem, digoxin or both, in patients admitted for treatment of atrial fibrillation between January 1993 and July 1996 was analyzed. SAS data sets were created to combine financial records with clinical files. The primary outcomes of interest measured were the length of hospital stay (LOS), total hospital cost, hospital mortality and 30 day readmission rates. RESULTS: A total of 107 patients were identified in the University HealthSystem Consortium (UHC) clinical data base (CDB) with admissions for treatment of atrial fibrillation. Forty-six, 41 and 20 patients received intravenous diltiazem, digoxin or both agents, respectively. Hospital mortality rates were not different among patients. The most common concomitant disease states included congestive heart failure (n=28) and hypertension (n=9). The mean LOS was 4.11, 8.34 and 9.15 days for patients receiving diltiazem, digoxin or both agents, respectively. The mean total cost of hospitalization was $4,890, $11,063 and $13,547 for patients receiving diltiazem, digoxin or both agents, respectively. More patients receiving both agents were readmitted within 30 days (25%) as compared to patients receiving only diltiazem (8%) or digoxin (22%). CONCLUSION: Intravenous diltiazem was associated with a decreased LOS, decreased total hospital costs, a decreased 30 day readmission rate and no difference in mortality in comparison with intravenous digoxin. Therefore, intravenous diltiazem warrants further consideration as a replacement for intravenous digoxin in the cost-effective management of atrial fibrillation.