1. ST Segment Changes: Identifying MI Mimics
Leanna R. Miller, RN, MN, CCRN-CSC, PCCN-CMC, CEN, CNRN, CMSRN, NP
Education Specialist
LRM Consulting
Nashville, TN

2. Place Your Phone & Beeper on Silence!!!

3. ST Segment Changes: Identifying MI Mimics
Objectives
Evaluate common abnormalities that mimic myocardial infarction.
Identify the criteria for pericarditis and evidence – based interventions.
Differentiate between pulmonary embolus and myocardial infarction using diagnostic criteria.

4. ST Segment Changes: Identifying MI Mimics
Acute Coronary Syndromes
Unstable Angina
Non ST segment Elevation MI (NSTEMI)
ST segment Elevation MI (STEMI)

5. ST Segment Changes: Identifying MI Mimics

6. ST Segment Changes: Identifying MI Mimics
Acute Coronary Syndromes
Clinical Symptoms
typical
atypical

7. ST Segment Changes: Identifying MI Mimics
Acute Coronary Syndromes
Diagnostics
Echocardiography
Lab
ABGs
H & H
enzymes

8. ST Segment Changes: Identifying MI Mimics
Acute Coronary Syndromes
Diagnostics
ECG (12 or 15 lead)
T wave inversion
ST segment elevation
Q wave
reciprocal ST segment
depression

9. ST Segment Changes: Identifying MI Mimics

10. ST Segment Changes: Identifying MI Mimics
SITE
INDICATIVE
RECIPROCAL
Septal
V1, V2
None
Anterior
V2, V3, V4
Anteroseptal
V1, V2, V3, V4
Lateral
I, aVL, V5, V6
II, III, aVF
Anterolateral
I, aVL, V3, V4, V5, V6
Inferior
I, aVL, V2, V3
Posterior

11. ST Segment Changes: Identifying MI Mimics

12. Variation to ST – Segment Elevation
ST Segment Changes: Identifying MI Mimics
Variation to ST – Segment Elevation

13. ST Segment Changes: Identifying MI Mimics

14. ST Segment Changes: Identifying MI Mimics
High acute risk factors for progression to
myocardial infarction or death
recurrent chest pain at rest
dynamic ST-segment changes: ST-segment depression > 0.1 mV or transient (<30 min) ST-segment elevation >0.1 mV
elevated Troponin-I, Troponin-T, or CK-MB levels

15. ST Segment Changes: Identifying MI Mimics
High acute risk factors for progression to
myocardial infarction or death
hemodynamic instability within the observation period
major arrhythmias (ventricular tachycardia, ventricular fibrillation)
early post-infarction unstable angina
diabetes mellitus

16. ST Segment Changes: Identifying MI Mimics
Anterolateral MI

17. ST Segment Changes: Identifying MI Mimics
Left Main Occlusion
Septal
Anterior
Lateral

18. ST Segment Changes: Identifying MI Mimics
Posterioinferior

19. ST Segment Changes: Identifying MI Mimics
Inferior with right ventricular involvement

20. ST Segment Changes: Identifying MI Mimics

21. ST Segment Changes: Identifying MI Mimics

22. ST Segment Changes: Identifying MI Mimics
Acute Pericarditis
Introduction
causes physical discomfort
predisposition to tachydysrhythmias

23. ST Segment Changes: Identifying MI Mimics
Acute Pericarditis
ECG Criteria
ST segment elevation
PR segment depression
T wave flattening or inversion
atrial dysrhythmias

24. ST Segment Changes: Identifying MI Mimics
Acute Pericarditis
ST segment elevation
not isolated or discrete segments
upward concavity
may be notching at the junction of
QRS and ST segment
no reciprocal ST segment depression

25. ST Segment Changes: Identifying MI Mimics
Acute Pericarditis
PR interval
interval between end of P wave and
beginning of QRS may be depressed
most often seen in lead II and V
leads may be only ECG finding

26. ST Segment Changes: Identifying MI Mimics
Acute Pericarditis
T wave flattening or inversion
no T wave inversion during acute phase
uncomplicated pericarditis: negative
T waves only occur in leads which usually
have negative T waves (aVR & V1)

27. ST Segment Changes: Identifying MI Mimics
Acute Pericarditis
Atrial dysrhythmias
SVT in postoperative open heart patient
treat with low dose steroids

28. ST Segment Changes: Identifying MI Mimics

29. ST Segment Changes: Identifying MI Mimics
Acute Pericarditis
Complications (pericardial effusion)
dampening of electrical output
low voltage in all leads
ST segment & T wave changes

30. ST Segment Changes: Identifying MI Mimics
Acute Pericarditis
Complications (pericardial effusion)
freely rotating heart produces
electrical alternans

31. ST Segment Changes: Identifying MI Mimics
Dressler’s Syndrome
Introduction
postmyocardial infarction syndrome
autoimmune process

32. ST Segment Changes: Identifying MI Mimics
Dressler’s Syndrome
Clinical Presentation
low – grade fever
chest pain (worsens with deep
breath; lessens with sitting up
and leaning forward)
pericardial friction rub

33. ST Segment Changes: Identifying MI Mimics
Dressler’s Syndrome
12 – lead ECG
diffuse ST segment elevation across the precordial leads

34. ST Segment Changes: Identifying MI Mimics
Dressler’s Syndrome
Treatment
corticosteroid administration
monitor for complications (effusion)

35. ST Segment Changes: Identifying MI Mimics
Pulmonary Embolus
Introduction
sudden massive PE produces ECG changes
must get 12 – lead to rule out MI

36. ST Segment Changes: Identifying MI Mimics
Pulmonary Embolus
ECG Findings
RVH with strain
RBBB pattern in V1
large S wave in Lead I; large Q wave in Lead
III (S1Q3 pattern)

37. ST Segment Changes: Identifying MI Mimics

38. ST Segment Changes: Identifying MI Mimics

39. ST Segment Changes: Identifying MI Mimics
Ventricular Aneurysm
Introduction (etiology)
myocardial infarction
congenital
cardiomyopathy
inflammatory
idiopathic

40. ST Segment Changes: Identifying MI Mimics
Ventricular Aneurysm
Introduction
infereolateral wall of LV
symptoms include CHF & exercise –
induced syncope (VT)

41. ST Segment Changes: Identifying MI Mimics
Ventricular Aneurysm
ECG Findings
persistent ST segment elevation
small q wave in II, III, & aVF
sustained VT with RBBB morphology

42. ST Segment Changes: Identifying MI Mimics

43. ST Segment Changes: Identifying MI Mimics

44. ST Segment Changes: Identifying MI Mimics

45. ST Segment Changes: Identifying MI Mimics
Ventricular Aneurysm
Treatment
surgical resection
antidysrhythmics
anticoagulants
treat heart failure
ablation therapy

46. ST Segment Changes: Identifying MI Mimics

47. ST Segment Changes: Identifying MI Mimics
Left Bundle Branch Block (LBBB)
QRS duration > 0.12 second
absence of septal q waves and S wave
in I, aVL, & V5 – 6 (+ complex usually
notched)
broad QS or rS in V1 – 3 (- complex)

48. ST Segment Changes: Identifying MI Mimics
Left Bundle Branch Block (LBBB)
S – T, T wave changes in leads I,
aVL & V5 – 6 (T wave opposite QRS)
delayed intrinsicoid deflection over
left ventricle (V6); normal over V1

49. ST Segment Changes: Identifying MI Mimics
Left Bundle Branch Block (LBBB)
hypertensive heart disease
aortic stenosis
degenerative changes of the conduction
system
coronary artery disease

50. ST Segment Changes: Identifying MI Mimics

51. ST Segment Changes: Identifying MI Mimics

52. ST Segment Changes: Identifying MI Mimics

53. ST Segment Changes: Identifying MI Mimics

54. ST Segment Changes: Identifying MI Mimics

55. ST Segment Changes: Identifying MI Mimics
LBBB with Acute Myocardial Infarction

56. Left Ventricular Hypertrophy
ST Segment Changes: Identifying MI Mimics
Left Ventricular Hypertrophy

57. ST Segment Changes: Identifying MI Mimics

58. Left Ventricular Hypertrophy
ST Segment Changes: Identifying MI Mimics
Left Ventricular Hypertrophy

59. ST Segment Changes: Identifying MI Mimics
Brugada Syndrome
autosomal dominant inheritance (SCN5A) gene
sodium channel involvement in 25% of the patients
Asian populations (58%)
high incidence of polymorphic ventricular tachycardias

60. ST Segment Changes: Identifying MI Mimics
Brugada Syndrome
found in right precordial leads
prominent J wave
ST – segment elevation in the absence of structural heart disease
three types

61. ST Segment Changes: Identifying MI Mimics
Brugada Syndrome
Type I: ST – segment elevation is triangular and T waves may be inverted in V1 – V3
Type II: downward displacement of ST – segment (does not reach baseline)
Type III: middle part of ST segment touches baseline

62. ST Segment Changes: Identifying MI Mimics

63. ST Segment Changes: Identifying MI Mimics
Brugada Syndrome

64. ST Segment Changes: Identifying MI Mimics
LBBB
Infarction Resemblance
ST segment elevation in the negatively deflected leads, (V1 – V3)
QS complexes in the negatively deflected leads, (V1 – V3)
Recognition
Wide QRS
QS in V1

65. ST Segment Changes: Identifying MI Mimics
Ventricular Rhythms
Infarction Resemblance
ST segment elevation in the negatively deflected leads, (V1 – V3)
QS complexes in the negatively deflected leads, (V1 – V3)
Recognition
Wide QRS following pacer spike
Negative V1 (RV paced)

66. ST Segment Changes: Identifying MI Mimics
LVH
Infarction Resemblance
ST segment elevation in the negatively deflected leads, (V1 – V3)
Recognition
Choose deepest S wave from V1 and V2
Choose tallest R wave from V5 and V6
Add deflections of tallest R wave and deepest S wave
Suspect LVH if total is > 35

67. ST Segment Changes: Identifying MI Mimics
Pericarditis
Infarction Resemblance
ST segment elements in multiple leads
Recognition
ST segment elevation not in anatomical grouping
PR segment deprewsion
Notching of the J point

68. ST Segment Changes: Identifying MI Mimics
Acute Pulmonary Emboli
Infarction Resemblance
RVH with strain pattern
RBBB pattern in V1
S1Q3 on frontal plane
Recognition
Patient is symptomatic with atypical cardiac pain
Elevates BMP
r/o with spiral CT/angiogram

69. ST Segment Changes: Identifying MI Mimics
Ventricular Aneurysm
Infarction Resemblance
High risk for ventricular dysrhythmias (VT with RBBB pattern)
Inferolateral MI
Persistent ST segment elevation
Small q wave in II, III, aVL
Recognition
Structural abnormality on ECHO
CHF & exercise – induced syncope (VT)

70. ST Segment Changes: Identifying MI Mimics
Brugada Syndrome
Infarction Resemblance
Ventricular dysrhythmias (polymorphic VT)
ST segment elevation in right precordial leads
Recognition
Autosomal dominant
Asian culture
No structural abnormality noted on ECHO

71. ST Segment Changes: Identifying MI Mimics
Prominent J with ST segment elevations
septal MI
RV cardiomyopathy
pericardial effusion
hypercalcemia

72. ST Segment Changes: Identifying MI Mimics
Prominent J with ST segment elevations
hyperkalemia
acute pulmonary embolism
subarachnoid hemorrhage
tricyclic antidepressant intoxication

73. ST Segment Changes: Identifying MI Mimics

74. ST Segment Changes: Identifying MI Mimics
In Conclusion
is the patient having a MI?
a variety of conditions can mimic infarction
ST segment changes