Very Rapid Treatment of STEMI:
Utilizing Pre-Hospital ECGs to
Bypass the Emergency Department
Kenneth W. Baran, MD
Medical Director for United Hospital’s Nasseff Heart Center
Catheterization Lab
Very Rapid Treatment of STEMI
Introduction
•
PCI is the preferred treatment for acute STEMI when performed
in a timely fashion.
•
The use of a 12 lead pre-hospital electrocardiogram (PH-ECG) has
been proposed as a strategy to reduce EMS-to balloon (E2B) and
door-to-balloon (D2B) times.
•
Rapid identification of STEMI patients in the field facilitates
transfer of patients directly to PCI capable hospitals.
•
In addition, early activation of the CV lab staff and the on-call
interventional cardiologist may minimize delays in transporting
patients from the ED to the CV lab.
Very Rapid Treatment of STEMI
Objectives
• We initiated a program to facilitate rapid transfer of STEMI
patients from the pre-hospital setting to the CV lab by
empowering EMS to interpret PH-ECGs and to activate the
hospital CV lab staff prior to the patient’s arrival at our
institution.
• A unique feature of our program was a time-saving
strategy to transport patients from the pre-hospital setting
directly to the CV lab, without stopping at any emergency
department.
Very Rapid Treatment of STEMI
Mechanisms
• Patients arrived at the CV lab via three different
mechanisms
 Direct transport from the pre hospital setting (home) to
the CV lab
 Transfer from referral hospital emergency department
 Transport from emergency department at our
institution
Very Rapid Treatment of STEMI
Hypothesis
• We hypothesized that the accuracy of EMS interpretation of
the PH-ECG, and therefore, the appropriateness of CV lab
activation, would be comparable to the accuracy of ECG
interpretation by MDs in the ED at our institution or by MDs
at referral hospital EDs.
Very Rapid Treatment of STEMI
Methods
PARTICIPANTS
EMS from 18 different organizations within a 45 mile radius of our
institution participated in this pilot program.
• 14 STEMI referral hospitals (SRH) without CV lab facilities also
participated.
•
EMPOWERING EMS
All participating EMS organizations had the ability to perform PHECGs, but several did not have fax transmission capabilities to
have PH-ECGs over-read by ED MDs.
• Therefore, we decided to empower EMS to interpret the PH-ECG
and to activate the CV lab team when a STEMI was diagnosed.
• ED MD or cardiologist over-read or “prior approval” was not
required.
•
Very Rapid Treatment of STEMI
Methods
SIMULTANEOUS ALERT SYSTEM
• A central paging system was used to simultaneously alert
the on-call CV lab staff, on-call interventional cardiologist,
our hospital ED and other hospital support personnel.
BYPASSING THE ED
• Patients were transported directly to the CV lab without
stopping at our ED if CV lab staff were on site and ready to
receive the patient.
Very Rapid Treatment of STEMI
Methods
DIDACTIC AND REVIEW SESSIONS
• Numerous ECG interpretation didactic sessions were
conducted for EMS by the authors.
• Accuracy of PH-ECG interpretation was adjudicated during
weekly review sessions by a panel of up to 4 physicians
including the authors and 2 non-interventional
cardiologists.
• Accuracy rates for EMS, referring hospital EDs, our hospital
ED and primary clinics are presented.
Very Rapid Treatment of STEMI
Results
• In a 24 month period from January 2007 to
December 2008, the CV lab was activated 574
times: EMS 209, STEMI referral hospital EDs
(SRH) 183, our STEMI referral center ED (SRC)
182.
Very Rapid Treatment of STEMI
Patient Flow Diagram
CV Lab Activations
574
EMS
209
Appropriate
Activation
156
STEMI
128
PCI
126
SRC ED
182
Other
28
No PCI 2
(2-expired)
Appropriate
Activation
138
False Activation
53
STEMI
119
PCI
114
SRH ED
183
Other
19
No PCI 5
(1-refused;
2-no intervention;
2 expired)
Appropriate
Activation
149
False Activation
44
STEMI
124
PCI
124
False Activation
34
Other
25
No PCI 0
Very Rapid Treatment of STEMI
Results
• No significant differences were detected
comparing the rates of accuracy of ECG
interpretation among the groups (EMS 75%, SRH
ED 81%, SRC ED 76%, p=0.24).
Very Rapid Treatment of STEMI
ECG Interpretation Accuracy Rates
Very Rapid Treatment of STEMI
Results
• Door to balloon (D2B) time with EMS activation
in the field (36 minutes) is significantly
decreased compared to D2B time when the CV
lab is activated through our ED (81 minutes)
p<0.0001.
• The ED bypass strategy reduced D2B more than
40 minutes regardless of time of presentation
(daytime D2B 22 minutes v. 64 minutes,
p<0.0001; after hours D2B 44 minutes v. 86
minutes, p<0.001)
Very Rapid Treatment of STEMI
Mean Door to Balloon Times (D2B)
Very Rapid Treatment of STEMI
Door to Balloon Times (Minutes)
EMS
SRC ED
p
SRH ED
N
Mean (SD) [95%CI]
Median (Q1,Q3)
N
Mean (SD) [95%CI]
Median (Q1,Q3)
N
Mean (SD) [95%CI]
Median (Q1,Q3)
All Hours
126
36 (19) [32-39]
35 (19,48)
114
81 (31) [75-87]
76 (61,98)
124
108 (43) [101-116]
98 (86,119)
<0.0001
Normal Hours
50
22 (12) [19-25]*
19 (15,24)
28
64 (32) [52-77] †
51 (44,78)
42
105 (35) [94-116] ‡
98 (81,112)
<0.0001
After Hours
76
44 (18) [40-48]*
45 (34,54)
86
86 (29) [80-93] †
77 (66,99)
82
110 (46) [100-121] ‡
99 (87,120)
<0.0001
* p<0.05
† p<0.05
‡ p=0.42
Very Rapid Treatment of STEMI
Results
• More patients in the EMS activation group
received PCI within 90 minutes
Cumulative Door to Balloon (D2B) Rates
Very Rapid Treatment of STEMI
Results
• 81% of patients in the EMS activation group had
PCI performed within 90 minutes of EMS arrival
at the pre-hospital setting
Cumulative Emergency Medical
Services to Balloon (E2B) Rates
Very Rapid Treatment of STEMI
Criteria for Emergency Medical Services Activation
of Cardiac Catheterization Lab
• Acute onset of chest pain <6 hours
• Typical ST elevation >1mm in 2 contiguous leads;
•
•
•
•
•
no wide QRS/LBBB
Computerized ECG interpretation diagnosing
acute MI helpful, but not mandatory
Nursing home patients should not be excluded;
use clinical judgment
Age should not be an exclusionary factor; use
clinical judgment
Patient must be conscious, able to provide
consent and reasonable history
No obvious end stage disease
Very Rapid Treatment of STEMI
Discussion
•
Reducing time to treatment (E2B and D2B) requires a multifaceted effort
to streamline the process of accurately diagnosing STEMI patients, rapidly
transporting them to the CV lab, and performing PCI quickly.
•
Pre-hospital diagnosis of STEMI with immediate activation of the CV lab
team by EMS (without waiting for MD over-read of PH-ECG) has the
potential to significantly reduce time to treatment. Delay in CV lab team
readiness is minimized, especially after hours.
•
Delegating the responsibility for ECG interpretation to EMS may result in
increased rates of inaccurate diagnosis and unnecessary CV lab team
activation. Our analysis, however, suggests that trained EMS personnel
can accurately identify ECG patterns of STEMI at a rate comparable to ED
MDs.
•
Mean time to treatment (D2B) is significantly reduced when this strategy
is utilized, resulting in a significantly higher percentage of patients who
receive definitive treatment in less than 90 minutes.