Inter-hospital transfer for primary angioplasty: delays are often due to diagnostic uncertainty rather than systems failure and universal time metrics may not be appropriate

Abstract

We aimed to investigate why many patients with ST-segment elevation myocardial infarction (STEMI) initially present to non-primary percutaneous coronary intervention (PPCI) equipped hospitals in a region that offers a 24-hour direct access Heart Attack Centre. A retrospective stratified consecutive case analysis was performed for 180 inter-hospital transfer (IHT) and 201 direct access PPCI patients. IHT and direct patients had similar age (61±1.8 years vs. 62±1.9 years, p=0.42), gender (76% vs. 78% male, p=0.64), and cardiovascular risk profile (hypertension 53% vs. 46%, p=0.18; hypercholesterolaemia 32% vs. 25%, p=0.22; and smoking 38% vs. 35%, p=0.56), though there were more diabetic patients in the IHT group (15% vs. 8%, p<0.05). The IHT group had longer symptom-call times 104 mins (42 mins-195 mins) vs. 46 mins (19 mins-114 mins), p<0.0001), lower ECG ST-elevation scores (3.0 mm [1.0-6.0] vs. 5.0 mm [3.0-9.0], p<0.0001), and more protocol negative ECGs at presentation (31.6% vs. 9.4%, p<0.0001). Peak CK was similar for the two groups (628 IU/L [191-1,144] vs. 603 IU/L [280-1,238], p=0.61), as was in-hospital (1.7% vs. 1.5%, p=0.89) and 30-day mortality (2.8% vs. 2.0%, p=0.61). This study suggests that reperfusion delays in PPCI due to IHT are not always simply "system failures". IHT patients appear to be a different patient cohort in which symptoms and early ECG changes may be less clear. In many cases, initial triage to a non-PPCI centre may be justifiable due to diagnostic uncertainty, and guideline time metrics should be amended appropriately.