Evaluation of acute ischemia in pre-procedure ECG predicts myocardial salvage after primary PCI in STEMI patients with symptoms >12hours

BACKGROUND: Primary percutaneous coronary intervention (pPCI) is recommended in patients with ST Elevation Myocardial Infarction (STEMI) and symptom duration <12hours. However, a considerable amount of myocardium might still be salvaged in STEMI patients with symptom durations >12hours (late-presenters). The Anderson-Wilkin's score (AW-score) estimates the acuteness of myocardial ischemia from the electrocardiogram (ECG) in STEMI patients. We hypothesized that the AW-score is superior to symptom duration in identifying substantial salvage potential in late-presenters.

METHODS: The AW-score (range 1-4) was obtained from the pre-pPCI ECG in 55 late-presenters and symptoms 12-72 hours. Myocardial perfusion imaging was performed to assess area at risk before pPCI and after 30days to assess myocardial salvage index (MSI). We correlated both the AW-score and pain-to-balloon with MSI and determined the salvage potential (MSI) according to AW-score ≥3 (acute ischemia) and AW-score <3 (late ischemia).

RESULTS: Late-presenters had median MSI 53% (inter quartile range (IQR) 27-89). The AW-score strongly correlated with MSI (β=0.60, R(2)=0.36, p<0.0001), while pain-to-balloon time did not (β=-0.21, R(2)=0.04, p=0.14). Patients with AW-score ≥3 (n=16) compared to those with AW-score <3 (n=27) had significant larger MSI (82.7% vs 41.5%, p=0.014). MSI>median was observed in 79% in patients with AW-score ≥3 vs 32% in patients with AW-score <3 (adjusted OR 6.74 [95% CI 1.35-33.69], p=0.02).

CONCLUSION: AW-score was strongly associated with myocardial salvage while pain-to-balloon time was not. STEMI patients with symptom duration between 12 -72hours and AW-score ≥3 achieved substantial salvage after pPCI.