Can we improve length of hospitalization in ST elevation myocardial infarction patients treated with primary percutaneous coronary intervention?

BACKGROUND: Patients with ST elevation myocardial infarction have traditionally been hospitalized for five to seven days to monitor for serious complications such as heart failure, arrhythmias, reinfarction and death. The Zwolle primary percutaneous coronary intervention (PCI) index is an externally validated risk score that has been used to identify low-risk primary PCI patients who can safely be discharged from the hospital within 48 h to 72 h.

METHODS: The Zwolle score was retrospectively applied to all ST elevation myocardial infarction patients treated with primary PCI between April 2004 and February 2006 at a large Canadian teaching hospital. The goal was to characterize length of stay (LOS) in low-risk patients and to identify variables that correlate with patients who were hospitalized longer than expected.

RESULTS: Data were collected on 255 patients. The mean LOS was 7.2+/-7.7 days (median 5.0 days [interquartile range 3.5 days]). A total of 179 patients (70%) had a Zwolle score of 3 or lower, identifying them as low risk. There was one death in the low-risk group (0.6% 30-day mortality) and 15 deaths in the higher-risk group (19.7% 30-day mortality), validating the Zwolle score in the population. A contraindication to early discharge was identified in 34 of the low-risk patients. Among the 144 remaining low-risk patients, the mean LOS was 5.1+/-3.3 days (median 4.0 days [interquartile range 3.0 days]). Only 8% were discharged within 48 h and only 28% within 72 h. It was determined that fewer patients were discharged on weekends and Wednesdays (when medical residents were away for teaching) than on other weekdays. LOS was longer among patients who were discharged on warfarin (7.6 days versus 4.6 days, P=0.006), and among patients who were transferred back to their presenting hospital rather than being discharged directly from the hospital where PCI was performed (5.6 days versus 4.0 days, P<0.001).

CONCLUSIONS: Seventy-two per cent of low-risk primary PCI patients were hospitalized longer than 72 h. The following three factors were identified as correlating with prolonged LOS in this population: fewer discharges on days when there was less resident staffing; the use of warfarin at discharge; and transfer of patients back to their presenting hospital rather than discharging them directly from the PCI-performing hospital. A programmed approach to the identification and early discharge of low-risk patients could have significant cost savings and should be investigated prospectively.