Clinical Outcomes Associated with Encounter To Balloon vs. Door To Balloon Times: A Retrospective Study

Background

Prior ST elevation myocardial infarction (STEMI) studies have focused on outcomes associated with shorter door to balloon (D2B) times. Little is known about clinical outcomes associated with encounter to balloon (E2B) times, which is defined as the time from initial evaluation by emergency medical services (EMS) in the field or by medical personnel in the clinic to percutaneous coronary intervention (PCI). The aim of this study was to evaluate E2B outcomes and compare these outcomes to patients who were evaluated initially in the emergency department, referred to as the door to balloon (ED-D2B) group.

Methods

A total of 189 patients with STEMI from 2012 to 2017 from our institution were evaluated. Patients who presented to the hospital in cardiac arrest, cardiogenic shock or who required pre-PCI intubation were excluded. All-cause mortality and major adverse cardiac cerebral events (MACCE) including subsequent unstable angina or non-STEMI, stroke and/or hospitalization for heart failure exacerbation were noted in each group and compared at hospital discharge, 30 days and at one year.

Results

There was a trend towards a lower incidence of a composite of all-cause mortality and MACCE in patients within the E2B group at one year compared to the ED-D2B group (6.8% vs. 13.9%, P=0.126). The median D2B time in the E2B group was significantly lower than in the ED-D2B group (51 min vs. 68.5 min, p<0.001). The E2B group had more Caucasians (65.8% vs. 50%, p=0.031) and lower incidence of a family history of coronary artery disease (CAD; 15.4% vs. 27.8%, p=0.039). In a subgroup analysis, there was a trend towards a comparatively lower incidence of a composite of all-cause mortality and MACCE at one year in the E2B group, particularly for non-diabetics (4.3% vs. 13%, P=0.067) and age <75 (3.4% vs. 10.7%, P=0.091).

Conclusions

The results show a trend towards better clinical outcomes in STEMI patients who were initially treated prior to hospital arrival, which may have been influenced in part by shorter D2B times, race and family history of CAD. Furthermore, there may be particular patient populations that derive more benefit than others from this early interaction. However, given the small sample size, these results will need to be validated in a larger study.