Purpose: Optimal duration of stay (DS) in angioplasty (PCI) treated uncomplicated acute ST-segment elevation myocardial infarction (STEMI) remains undetermined. The Zwolle risk score (ZRS) is a simple tool which could help identify patients who can be safely discharged before 72h. We aimed to apply ZRS to our population and assess the variables influencing DS.
Methods: 276 consecutive STEMI patients admitted for PCI were studied, between January 2009 and December 2010. ZRS, DS and 30-day mortality were obtained for all patients. Low risk was defined as ZRS≤3 and ROC curves were used for discriminative power.
Results: In the 276 patients evaluated (mean age 62±13 years-old, 75% male, 20% Killip>1), ZRS median was 3 (IQR 1-4). 171 patients were classified as low risk. These patients were younger (57.1 vs. 67.6 years-old, p<0.001), less often hypertensive (46.8 vs. 67.6%, p=0.001), less often diabetic (14.6 vs. 27.6%, p=0.012) and had less frequently serum creatinine>1.2 mg/dL (37.2 vs 62.8% p=0.001). Total 30-day mortality was 4.7% (13 patients). ZRS correctly predicted this event in 93.7% of cases (C-statistic 0.937; CI95% 0.906-0.968). 30-day mortality, stratified by ZRS, was significantly different in the 2 groups (0 vs. 12.4% p<0.001, Fig.1), corresponding to a positive predictive value of 100% (CI95% 97.0-100%) for safe early discharge. In the low risk subset of patients, mean duration of stay was substantially lower (6.0 vs. 15.1 days, p<0.001). The need for additional revascularization (20 patients, 11.7%) was the most frequent cause for longer DS.
Figure 1
Conclusions: In our population, a ZRS ≤3 had both high discriminative power and positive predictive value for safe early discharge, translating on the DS. A cost-benefit analysis is warranted to further assess the real impact of these results.
