Early discharge after primary percutaneous coronary intervention: the added value of N-terminal pro-brain natriuretic peptide to the Zwolle Risk Score

BACKGROUND: The Zwolle Risk Score (ZRS) identifies ST-elevation myocardial infarction (STEMI) patients treated with primary percutaneous coronary intervention (PPCI) eligible for early discharge. We aimed to investigate whether baseline N-terminal pro-brain natriuretic peptide (NT-proBNP) is also able to identify these patients and could improve future risk strategies.

METHODS AND RESULTS: PPCI patients included in the Ongoing Tirofiban in Myocardial Infarction Evaluation (On-TIME) II study were candidates (N=861). We analyzed whether ZRS and baseline NT-proBNP predicted 30-day mortality and assessed the occurrence of major adverse cardiac events (MACEs) and major bleeding. Receiver operating characteristic curve analysis was used to assess discriminative accuracy for ZRS, NT-pro-BNP, and their combination. After multiple imputation, 845 patients were included. Both ZRS >3 (hazard ratio [HR]=9.42; P<0.001) and log NT-pro-BNP (HR=2.61; P<0.001) values were associated with 30-day mortality. On multivariate analysis, both the ZRS (HR=1.41; 95% confidence interval [CI]=1.27 to 1.56; P<0.001) and log NT-proBNP (HR=2.09; 95% CI=1.59 to 2.74; P<0.001) independently predicted death at 30 days. The area under the curve for 30-day mortality for combined ZRS/NT-proBNP was 0.94 (95% CI=0.90 to 0.99), with optimal predictive values of a ZRS ≥2 and a NT-proBNP value of ≥200 pg/mL. Using these cut-off values, 64% of the study population could be identified as very low risk with zero mortality at 30 days follow-up and low occurrence of MACEs and major bleeding between 48 hours and 10 days (1.3% and 0.6%, respectively).

CONCLUSION: Baseline NT-proBNP identifies a large group of low-risk patients who may be eligible for early (48- to 72-hour) discharge, whereas optimal predictive accuracy is reached by the combination of both baseline NT-proBNP and ZRS.