20 to 30 minutes of ischemia, it
takes several hours for transmural
myocardial necrosis to develop.
The goal of reperfusion therapy
with fibrinolytic drugs or primary
percutaneous coronary intervention
(PCI) is to restore blood
flow to ischemic, but still viable,
myocardium and reduce infarct
size. Reducing the time to treatment
and maximizing myocardial
salvage — in keeping with the
mantra that “time is muscle” —
present a logistic challenge.
Early randomized trials of fibrinolytic
therapy established the
direct relationship between symptom
duration, myocardial infarct
size, and mortality. At the time,
however, treatment delays were
prolonged because of the lack of
prehospital and in-hospital systems
of care to facilitate timely
STEMI therapy. To address this
problem, the National Heart,
Lung, and Blood Institute launched
the National Heart Attack Alert
Program in 1991. Four critical
time points in the emergency department
(ED) were identified
and dubbed the “4Ds”: “door,”
the time of arrival in the ED;
“data,” the time of acquisition of
an electrocardiogram (ECG); “decision,”
the time of ordering of
fibrinolytic therapy; and “drug,”
the time of initiation of fibrinolytic
drug infusion. Within 3 years,
by reducing ED delays, participating
hospitals had doubled the percentage
of patients treated within
the door-to-needle goal of 30
minutes. The treatment goal is the
same today, but less than half of
patients in the United States are
treated within 30 minutes, perhaps
because fibrinolytic therapy
is used so infrequently.
Primary PCI has replaced fibrinolytic
therapy as the preferred
reperfusion strategy, despite the
delays inherent in transferring the
patient from the ED to the cardiac
catheterization laboratory and
then performing the procedure
(see the figure). The Centers for
Medicare and Medicaid Services
and the Joint Commission began
using door-to-balloon time as a
performance measure for public
reporting in 2002. In 2006, the
American College of Cardiology
(ACC) launched the Door-to-Balloon
Alliance with a goal of providing
treatment within 90 minutes
after arrival for at least 75%
of patients with STEMI who present
directly to a PCI-capable hospital.1
Several strategies were promoted,
including activation of
the cardiac catheterization laboratory
with a single call by the