Transcript AHA2006 David Larson,False positve STEMI

No conflicts of interest or financial ties to
disclose
False Positive ST Elevation in
Patients Undergoing Direct
Percutaneous Coronary
Intervention
David M. Larson MD, Katie M. Menssen, BS, Randall K
Johnson MD, Scott W Sharkey MD, Nicholas Burke MD,
James Harris MD, Robert Schwartz MD, Jay H Traverse MD,
Barbara T Unger RN, Timothy D. Henry MD,
Ridgeview Medical Center, Waconia, Minnesota and
Minneapolis Heart Institute Foundation, Minneapolis,
Minnesota
Introduction
• Previous data shows that up to 11% of
STEMI patients treated with thrombolysis
did not have a Myocardial Infarction (MI)
• ACC/AHA guidelines recommend that the
Emergency physician make the decision
regarding reperfusion therapy for STEMI
• There is limited data reporting the rate of
“false positive” ECGs in STEMI patients
treated with Percutaneous Coronary
Intervention.
Objective
1) To determine the incidence and
etiologies of “false positive” ECGs,
defined as: no culprit coronary vessel
and negative cardiac markers (no MI),
from a non-selected cohort of STEMI
patients.
2) To determine the incidence of “true
false positive” ECGs defined as no
culprit, no significant coronary disease
and negative cardiac markers.
Methods
• Minneapolis Heart Institute/Abbott
Northwestern Hospital (ANW) – a tertiary
cardiac center with referral relationships
with 30 community hospitals (CH) in
Minnesota and Wisconsin – instituted the
“MHI Level 1 MI Program” in 2003.
Methods
• Level 1 MI Protocol: Includes STEMI (ST
elevation or new Left Bundle Branch Block)
with symptom < 24hrs. Diagnosis and
decision to activate the cath lab is made by
the Emergency Physician at the presenting
hospital. Transferred patients go directly to
cath lab for Primary or Facilitated PCI
• Data obtained from a prospective registry of
all “Level 1 MI” patients that includes
clinical, laboratory, ECG, angiographic and
follow up data.
Results
• From 3/03 to 6/06, 1121 STEMI patients
enrolled in Level 1 MI program including
861 transferred from 28 rural or
community hospitals.
• 13.6% of STEMI patients undergoing
angiography did not have a clear culprit
(fig 1) however, 27% of these had
positive cardiac markers (Tables 1 and
2) and 35% had moderate to severe
coronary disease.
Figure 1
STEMI Diagnosis
N=1,121
Angiography
5 died prior to angio
2 no angiogram
N=1,114
PCI
Surgery
N=899 (80.7%)
N=37 (3.3%)
Medical
Management
No Angiographic
Culprit
N=26 (2.3%)
N=152 (13.6%)
Table 1
No Culprit and Negative Cardiac Biomarkers
(n=111)
Nonspecific ECG
30 (27%)
Vasospasm
3 (2.7%)
Pericarditis
20 (18%)
Pacemaker
2 (1.8%)
Benign early
repolarization/norm
al variant
16 (14.8%)
Cholecystitis
2 (1.8%)
Left Bundle Branch
Block
12 (10.8%)
Myocarditis
1 (0.9%)
Prior MI
8 (7.2%)
Aortic dissection
1 (0.9%)
Left Ventricular
Hypertrophy
8 (7.2%)
Atrial fib with rate
related ST
Elevation
1 (0.9%)
Right Bundle
Branch Block
6 (5.4%)
Intraventricular
Conduction Delay
1 (0.9%)
Table 2
No Culprit and Positive Cardiac Biomarkers (n=41)
Myocarditis
14 (31.8%)
Stress Cardiomyopathy
9 (21.9%)
NonSTEMI
8 (19.5%)
STEMI (embolic or spasm)
6 (14.6%)
Pulmonary embolus
2 (4.8%)
Post Cardiac Arrest
1 (2.4%)
Acute Mitral insufficiency
1 (2.4%)
Results
• 11.2% had negative cardiac makers (no MI)
• 9.9% had no culprit and negative cardiac
markers (no culprit + no MI)
• 6.4% had no culprit, normal Coronary arteries
and negative cardiac markers (no culprit +
normal CA + no MI)
• One year morality with a culprit was 7.4% vs
3.9% in those without (p=0.45)
• The rate of no culprit + no MI varied by
Emergency department annual volume (Fig 2)
Figure 2
No culprit/Neg biomarkers by Hospital
ED Volume
14
11.8
12
10
percent
8
10.4
9.5
9.7
6.2
6
4
2
0
ANW
> 20 K
20-10 K
< 10 K
ED visits/year
Cochran-Armitage Trend Test
p=0.01
Overall
Conclusions
• The incidence of “false positive” ECGs
in STEMI patients treated with Primary
PCI is similar to previous data in
patients treated with thrombolytic
therapy.
• Patients presenting with “False Positive”
ST elevation are a heterogeneous
group, many with other serious cardiac
conditions.
Conclusions
• Emergency physicians from a variety of
community and rural hospitals can
make appropriate diagnostic decisions
and activate the cath lab without
excessive false positive diagnosis of
STEMI, although there appears to be a
relation to ED volume.