BACKGROUND
The management of STEMI has evolved over the past 30 years and the
importance of timely reperfusion in STEMI by pharmacological or
catheter-based measures has been well
substantiated.5.9,10 Reperfusion of an occluded
coronary artery remains a significant contributor to positive patient
outcomes.4,5,8,11 D2B time is a recommended core
quality measure for the Joint Commission on Accreditation of Health Care
Organizations and the Centers for Medicare and Medicaid
Services.12 Achieving an overall D2B time ≤90 minutes
in Primary PCI centers is an important time target in acute STEMI care.3,13 The recommended minimal adherence score to a D2B
≤90 minutes is 75% of STEMI patients in the US.3,14There is evidence that D2B times are improving over time. An analysis of
all STEMI patients demonstrated that D2B times < 90
minutes increased from 44.2% to 91.4% over a period from December 31,
2005 to September 30, 2010.15 Short D2B time is
important because a delay in treatment for STEMI increases the
likelihood and amount of cardiac muscle damage due to localized
hypoxia.5
An ECG is the initial diagnostic indicator of
STEMI.4,5 Delay in obtaining an ECG adversely
influences D2B time and has commanded extensive investigation in the
past. An important time target in
acute STEMI management is to obtain an ECG in ≤10 minutes from time of
admission.3-5,13 An integrated approach that includes
chief-complaint-based ECG processes initiated by a triage nurse could
improve the target rate of door-to-ECG time of < 10
minutes for potential STEMI patients.16 Both target
rate of door-to-ECG < 10 minutes and D2B times< 90 were significantly increased. The integrated ECG
approach remained a significant predictor of door-to-ECG time ≤10
minutes beyond the contribution of other covariates.
Current guidelines strongly recommend that all patients with STEMI
symptoms seek emergency medical services (EMS) and arrive at the
hospital via ambulance.10,17 EMS activation shortens
the time to definitive treatment, facilitates obtaining an ECG early,
allows for prompt activation of the STEMI team, and significantly
improves D2B time.17-19 Prior studies regarding mode
of transportation indicate low EMS use by STEMI patients (10-53%), use
of private transportation (16% self-driving) and suboptimal improvement
in EMS use (14-20%) despite extensive community campaigns to educate
the public.19-22 Recent data demonstrated slightly
better EMS use (60-62%) for STEMI patients directly presenting to PCI
capable hospitals. 10,17 Wireless ECG transmission
from the ambulance, and verification of probable STEMI from the ED
physician or cardiologist prevents delays that occur in the
ED.23 Although CCL pre-activation is recognized as an
important factor in treating STEMI patients, it was found to occur in
only 41% of patients with STEMI. 24 Mumma and
associates found that a prehospital ECG was associated with a 10-minute
reduction in first medical contact to balloon time.25Patients who have symptoms of ischemic chest pain and who have
pre-hospital ECG changes consistent with STEMI should optimally bypass
the ED and be transported directly to the CCL.26,27
Confounders may significantly contribute to a delay in reperfusion.
Patient-related confounders are primarily comorbidities or an unstable
clinical presentation, including inconclusive ECG findings, family
interference, patient refusal, unstable hemodynamics, cardiac arrest and
procedural difficulties.6,28 Non-patient-related
confounders are generally system-related difficulties such as
availability of the CCL, inadequate staff, holidays and after-hours
procedures. Weather can impede EMS ability to transport patients to the
hospital.7,29