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

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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.

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

ST Segment Changes: Identifying MI Mimics

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

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

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

ST Segment Changes: Identifying MI Mimics

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

ST Segment Changes: Identifying MI Mimics

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

ST Segment Changes: Identifying MI Mimics

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

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

ST Segment Changes: Identifying MI Mimics Anterolateral MI

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

ST Segment Changes: Identifying MI Mimics Posterioinferior

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

ST Segment Changes: Identifying MI Mimics

ST Segment Changes: Identifying MI Mimics

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

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

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

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

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)

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

ST Segment Changes: Identifying MI Mimics

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

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

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

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

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

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

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

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)

ST Segment Changes: Identifying MI Mimics

ST Segment Changes: Identifying MI Mimics

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

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

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

ST Segment Changes: Identifying MI Mimics

ST Segment Changes: Identifying MI Mimics

ST Segment Changes: Identifying MI Mimics

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

ST Segment Changes: Identifying MI Mimics

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)

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

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

ST Segment Changes: Identifying MI Mimics

ST Segment Changes: Identifying MI Mimics

ST Segment Changes: Identifying MI Mimics

ST Segment Changes: Identifying MI Mimics

ST Segment Changes: Identifying MI Mimics

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

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

ST Segment Changes: Identifying MI Mimics

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

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

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

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

ST Segment Changes: Identifying MI Mimics

ST Segment Changes: Identifying MI Mimics Brugada Syndrome

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

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)

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

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

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

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)

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

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

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

ST Segment Changes: Identifying MI Mimics

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