The Complete Guide to ECGs — Complete Test Bank
,The Complete Guide to ECGs — Complete Test Bank
COMPLETE TEST BANK — ALL 7 SECTIONS
| Multiple Choice & True/False | All Answers Include Rationale
Section 1 — 25 Questions: Common Dilemmas in ECG Interpretation for
Certifying Exams
Section 2 — 40 Questions: Approach to ECG Interpretation
Section 3 — 40 Questions: ECG Differential Diagnosis
Section 4 — 20 Questions: ECG Cases
Section 5 — 20 Questions: Questions & Answers
Section 6 — 20 Questions: Pop Quizzes
Section 7 — 40 Questions: ECG Criteria — General Features & Abnormalities
,The Complete Guide to ECGs — Complete Test Bank
Section 1: Common Dilemmas in ECG Interpretation for
Certifying Exams
Question 1 [Multiple Choice]
On a certifying exam, when you encounter an ECG with a wide QRS complex
tachycardia, what should be your default diagnosis until proven otherwise?
A. Supraventricular tachycardia with aberrant conduction
B. Ventricular tachycardia
C. Atrial fibrillation with WPW
D. Sinus tachycardia with bundle branch block
Correct Answer: B. Ventricular tachycardia
Rationale: Ventricular tachycardia (VT) accounts for the vast majority of wide-
complex tachycardias, especially in patients with structural heart disease. On
certifying exams, wide QRS tachycardia should always be presumed VT until
there is clear evidence to the contrary. Misdiagnosing VT as SVT with aberrancy
is a classic and dangerous error.
Question 2 [True/False]
True or False: A normal ECG rules out the presence of significant cardiac
disease.
Correct Answer: False
Rationale: A normal ECG does not exclude serious cardiac conditions. Patients
with significant coronary artery disease, early cardiomyopathy, or paroxysmal
arrhythmias may have a completely normal ECG between episodes. This is a
common dilemma on certifying exams — the ECG must always be interpreted in
clinical context.
,The Complete Guide to ECGs — Complete Test Bank
Question 3 [Multiple Choice]
Which of the following is the most reliable way to distinguish sinus
tachycardia from other forms of supraventricular tachycardia on a certifying
exam?
A. Heart rate greater than 150 bpm
B. Presence of upright P waves in lead II preceding each QRS
C. Narrow QRS complex
D. Regular RR interval
Correct Answer: B. Presence of upright P waves in lead II preceding each QRS
Rationale: Sinus tachycardia is defined by a normal P wave axis — upright P
waves in lead II that precede every QRS complex with a consistent PR interval.
Rate alone cannot distinguish sinus tachycardia from other SVTs, and a narrow
QRS or regular rhythm can be seen in multiple tachycardias.
Question 4 [Multiple Choice]
On a certifying exam ECG, you see ST elevation in leads V1–V4 with a right
bundle branch block pattern. What is the most important diagnosis to
consider?
A. Brugada syndrome
B. Early repolarization
C. Anterior ST-elevation myocardial infarction
D. Left ventricular hypertrophy
Correct Answer: C. Anterior ST-elevation myocardial infarction
Rationale: New ST elevation in the anterior leads (V1–V4) in the context of a
right bundle branch block (RBBB) pattern must raise immediate concern for
anterior STEMI. While RBBB causes some ST changes, significant ST elevation
should never be attributed solely to the RBBB pattern without ruling out acute
MI.
,The Complete Guide to ECGs — Complete Test Bank
Question 5 [True/False]
True or False: Left bundle branch block (LBBB) makes it impossible to
diagnose acute myocardial infarction on ECG.
Correct Answer: False
Rationale: While LBBB significantly complicates MI diagnosis by altering ST
and T wave patterns, acute MI can still be identified using Sgarbossa criteria.
Concordant ST elevation ≥1 mm in leads with a positive QRS, concordant ST
depression ≥1 mm in V1–V3, and discordant ST elevation ≥5 mm all suggest
acute MI in the setting of LBBB.
Question 6 [Multiple Choice]
A common pitfall on certifying exams is misidentifying artifact as a
pathological rhythm. Which feature most reliably distinguishes artifact from
true ventricular fibrillation?
A. Irregular baseline undulations
B. Normal QRS complexes visible within or around the 'chaotic' activity
C. Rate greater than 300 bpm
D. Absence of P waves
Correct Answer: B. Normal QRS complexes visible within or around the
'chaotic' activity
Rationale: The hallmark of artifact mimicking VF is the presence of normally
conducted QRS complexes marching through the 'chaotic' activity at a regular
rate. In true VF, there are no organized QRS complexes. Identifying this feature
prevents misdiagnosis and inappropriate treatment recommendations on
exams.
Question 7 [Multiple Choice]
On a certifying exam, which lead is most useful for identifying P wave
morphology and distinguishing the origin of a supraventricular rhythm?
,The Complete Guide to ECGs — Complete Test Bank
A. Lead I
B. Lead aVR
C. Lead II
D. Lead V5
Correct Answer: C. Lead II
Rationale: Lead II is oriented along the axis of normal atrial depolarization
(toward the inferior left). It provides the best view of P wave morphology,
making it the go-to lead for identifying sinus rhythm (upright P wave) versus
ectopic atrial rhythms. It is also the most commonly used rhythm strip lead.
Question 8 [True/False]
True or False: A delta wave on ECG is always associated with symptomatic
tachyarrhythmias.
Correct Answer: False
Rationale: A delta wave indicates ventricular pre-excitation through an
accessory pathway (Wolff-Parkinson-White pattern), but many individuals with
this finding are asymptomatic and never develop tachyarrhythmias. On
certifying exams, it is important to distinguish the WPW 'pattern' (ECG finding
alone) from WPW 'syndrome' (pattern plus symptomatic arrhythmias).
Question 9 [Multiple Choice]
When interpreting an ECG for a certifying exam, which of the following QT
intervals would be classified as prolonged in an adult male?
A. QTc of 380 ms
B. QTc of 420 ms
C. QTc of 460 ms
D. QTc of 390 ms
Correct Answer: C. QTc of 460 ms
,The Complete Guide to ECGs — Complete Test Bank
Rationale: A corrected QT interval (QTc) is prolonged when it exceeds 450 ms
in males and 460 ms in females (some guidelines use 440 ms for males). QTc of
460 ms exceeds the threshold for males and is therefore classified as prolonged.
Prolonged QTc predisposes to Torsades de Pointes, a potentially fatal
arrhythmia.
Question 10 [Multiple Choice]
A common dilemma on certifying exams is differentiating left anterior
fascicular block (LAFB) from other causes of left axis deviation. Which finding
is most specific for LAFB?
A. QRS duration ≥ 120 ms
B. Left axis deviation between -30° and -90° with qR in lead I and rS in lead
II
C. Broad R wave in lead V6
D. ST depression in leads II, III, and aVF
Correct Answer: B. Left axis deviation between -30° and -90° with qR in lead
I and rS in lead II
Rationale: LAFB causes marked left axis deviation (typically -45° to -90°) with
a characteristic qR pattern in lead I and rS pattern in leads II and III. QRS
duration is only mildly prolonged (<120 ms) in isolated LAFB. This combination
is highly specific and distinguishes LAFB from inferior MI or LVH as causes of left
axis deviation.
Question 11 [True/False]
True or False: On certifying exams, ST segment depression in leads V1–V3
may represent a true posterior wall myocardial infarction.
Correct Answer: True
Rationale: Posterior MI produces ST depression (not elevation) in the anterior
leads V1–V3 because these leads are electrically opposite to the posterior wall.
This is a classic certifying exam dilemma. Posterior MI should be suspected when
,The Complete Guide to ECGs — Complete Test Bank
anterior ST depression is accompanied by tall, broad R waves and upright T
waves in V1–V2 — essentially a 'mirror image' of an anterior STEMI.
Question 12 [Multiple Choice]
On a certifying exam, you must interpret a 12-lead ECG with no P waves and
an irregularly irregular rhythm. What is the most likely diagnosis?
A. Sinus arrhythmia
B. Third-degree AV block
C. Atrial fibrillation
D. Multifocal atrial tachycardia
Correct Answer: C. Atrial fibrillation
Rationale: Atrial fibrillation is characterized by the absence of discrete P waves
(replaced by fibrillatory baseline), an irregularly irregular ventricular response,
and narrow QRS complexes (unless aberrant conduction is present). This
combination is pathognomonic for AF and is one of the highest-yield rhythms on
all cardiology certifying exams.
Question 13 [Multiple Choice]
Which of the following ECG findings is most suggestive of hyperkalemia, a
condition frequently tested on certifying exams?
A. Short QT interval with J waves
B. Prolonged PR interval with delta waves
C. Tall, narrow, peaked T waves with widening QRS
D. ST elevation in aVR with global ST depression
Correct Answer: C. Tall, narrow, peaked T waves with widening QRS
Rationale: Hyperkalemia produces a sequential progression of ECG changes.
Early changes include tall, narrow, symmetric (peaked/tent-shaped) T waves. As
potassium rises, PR prolongation and QRS widening occur. Severe hyperkalemia
, The Complete Guide to ECGs — Complete Test Bank
can lead to a sine-wave pattern and cardiac arrest. This progression is a high-
yield topic for all cardiology and internal medicine boards.
Question 14 [True/False]
True or False: Sinus arrhythmia is a pathological finding that requires further
workup when identified on a certifying exam ECG.
Correct Answer: False
Rationale: Sinus arrhythmia — a variation in heart rate with respiration (rate
increases with inspiration, decreases with expiration) — is a normal
physiological finding, particularly in young adults and athletes. The P wave
morphology remains normal and the PR interval is consistent. On certifying
exams, sinus arrhythmia should be identified as a normal variant, not a
pathological condition requiring further evaluation.
Question 15 [Multiple Choice]
A certifying exam ECG shows a regular narrow-complex tachycardia at 150
bpm. What is the most important diagnosis to consider?
A. Sinus tachycardia
B. Atrial flutter with 2:1 conduction
C. AV nodal reentrant tachycardia
D. Junctional tachycardia
Correct Answer: B. Atrial flutter with 2:1 conduction
Rationale: Atrial flutter classically produces an atrial rate of ~300 bpm with
2:1 AV conduction, resulting in a ventricular rate of ~150 bpm. This is one of the
most commonly missed diagnoses on certifying exams because flutter waves may
be hidden in QRS complexes or T waves. When a regular tachycardia presents at
exactly 150 bpm, atrial flutter should always be the first consideration.
Question 16 [Multiple Choice]
,The Complete Guide to ECGs — Complete Test Bank
COMPLETE TEST BANK — ALL 7 SECTIONS
| Multiple Choice & True/False | All Answers Include Rationale
Section 1 — 25 Questions: Common Dilemmas in ECG Interpretation for
Certifying Exams
Section 2 — 40 Questions: Approach to ECG Interpretation
Section 3 — 40 Questions: ECG Differential Diagnosis
Section 4 — 20 Questions: ECG Cases
Section 5 — 20 Questions: Questions & Answers
Section 6 — 20 Questions: Pop Quizzes
Section 7 — 40 Questions: ECG Criteria — General Features & Abnormalities
,The Complete Guide to ECGs — Complete Test Bank
Section 1: Common Dilemmas in ECG Interpretation for
Certifying Exams
Question 1 [Multiple Choice]
On a certifying exam, when you encounter an ECG with a wide QRS complex
tachycardia, what should be your default diagnosis until proven otherwise?
A. Supraventricular tachycardia with aberrant conduction
B. Ventricular tachycardia
C. Atrial fibrillation with WPW
D. Sinus tachycardia with bundle branch block
Correct Answer: B. Ventricular tachycardia
Rationale: Ventricular tachycardia (VT) accounts for the vast majority of wide-
complex tachycardias, especially in patients with structural heart disease. On
certifying exams, wide QRS tachycardia should always be presumed VT until
there is clear evidence to the contrary. Misdiagnosing VT as SVT with aberrancy
is a classic and dangerous error.
Question 2 [True/False]
True or False: A normal ECG rules out the presence of significant cardiac
disease.
Correct Answer: False
Rationale: A normal ECG does not exclude serious cardiac conditions. Patients
with significant coronary artery disease, early cardiomyopathy, or paroxysmal
arrhythmias may have a completely normal ECG between episodes. This is a
common dilemma on certifying exams — the ECG must always be interpreted in
clinical context.
,The Complete Guide to ECGs — Complete Test Bank
Question 3 [Multiple Choice]
Which of the following is the most reliable way to distinguish sinus
tachycardia from other forms of supraventricular tachycardia on a certifying
exam?
A. Heart rate greater than 150 bpm
B. Presence of upright P waves in lead II preceding each QRS
C. Narrow QRS complex
D. Regular RR interval
Correct Answer: B. Presence of upright P waves in lead II preceding each QRS
Rationale: Sinus tachycardia is defined by a normal P wave axis — upright P
waves in lead II that precede every QRS complex with a consistent PR interval.
Rate alone cannot distinguish sinus tachycardia from other SVTs, and a narrow
QRS or regular rhythm can be seen in multiple tachycardias.
Question 4 [Multiple Choice]
On a certifying exam ECG, you see ST elevation in leads V1–V4 with a right
bundle branch block pattern. What is the most important diagnosis to
consider?
A. Brugada syndrome
B. Early repolarization
C. Anterior ST-elevation myocardial infarction
D. Left ventricular hypertrophy
Correct Answer: C. Anterior ST-elevation myocardial infarction
Rationale: New ST elevation in the anterior leads (V1–V4) in the context of a
right bundle branch block (RBBB) pattern must raise immediate concern for
anterior STEMI. While RBBB causes some ST changes, significant ST elevation
should never be attributed solely to the RBBB pattern without ruling out acute
MI.
,The Complete Guide to ECGs — Complete Test Bank
Question 5 [True/False]
True or False: Left bundle branch block (LBBB) makes it impossible to
diagnose acute myocardial infarction on ECG.
Correct Answer: False
Rationale: While LBBB significantly complicates MI diagnosis by altering ST
and T wave patterns, acute MI can still be identified using Sgarbossa criteria.
Concordant ST elevation ≥1 mm in leads with a positive QRS, concordant ST
depression ≥1 mm in V1–V3, and discordant ST elevation ≥5 mm all suggest
acute MI in the setting of LBBB.
Question 6 [Multiple Choice]
A common pitfall on certifying exams is misidentifying artifact as a
pathological rhythm. Which feature most reliably distinguishes artifact from
true ventricular fibrillation?
A. Irregular baseline undulations
B. Normal QRS complexes visible within or around the 'chaotic' activity
C. Rate greater than 300 bpm
D. Absence of P waves
Correct Answer: B. Normal QRS complexes visible within or around the
'chaotic' activity
Rationale: The hallmark of artifact mimicking VF is the presence of normally
conducted QRS complexes marching through the 'chaotic' activity at a regular
rate. In true VF, there are no organized QRS complexes. Identifying this feature
prevents misdiagnosis and inappropriate treatment recommendations on
exams.
Question 7 [Multiple Choice]
On a certifying exam, which lead is most useful for identifying P wave
morphology and distinguishing the origin of a supraventricular rhythm?
,The Complete Guide to ECGs — Complete Test Bank
A. Lead I
B. Lead aVR
C. Lead II
D. Lead V5
Correct Answer: C. Lead II
Rationale: Lead II is oriented along the axis of normal atrial depolarization
(toward the inferior left). It provides the best view of P wave morphology,
making it the go-to lead for identifying sinus rhythm (upright P wave) versus
ectopic atrial rhythms. It is also the most commonly used rhythm strip lead.
Question 8 [True/False]
True or False: A delta wave on ECG is always associated with symptomatic
tachyarrhythmias.
Correct Answer: False
Rationale: A delta wave indicates ventricular pre-excitation through an
accessory pathway (Wolff-Parkinson-White pattern), but many individuals with
this finding are asymptomatic and never develop tachyarrhythmias. On
certifying exams, it is important to distinguish the WPW 'pattern' (ECG finding
alone) from WPW 'syndrome' (pattern plus symptomatic arrhythmias).
Question 9 [Multiple Choice]
When interpreting an ECG for a certifying exam, which of the following QT
intervals would be classified as prolonged in an adult male?
A. QTc of 380 ms
B. QTc of 420 ms
C. QTc of 460 ms
D. QTc of 390 ms
Correct Answer: C. QTc of 460 ms
,The Complete Guide to ECGs — Complete Test Bank
Rationale: A corrected QT interval (QTc) is prolonged when it exceeds 450 ms
in males and 460 ms in females (some guidelines use 440 ms for males). QTc of
460 ms exceeds the threshold for males and is therefore classified as prolonged.
Prolonged QTc predisposes to Torsades de Pointes, a potentially fatal
arrhythmia.
Question 10 [Multiple Choice]
A common dilemma on certifying exams is differentiating left anterior
fascicular block (LAFB) from other causes of left axis deviation. Which finding
is most specific for LAFB?
A. QRS duration ≥ 120 ms
B. Left axis deviation between -30° and -90° with qR in lead I and rS in lead
II
C. Broad R wave in lead V6
D. ST depression in leads II, III, and aVF
Correct Answer: B. Left axis deviation between -30° and -90° with qR in lead
I and rS in lead II
Rationale: LAFB causes marked left axis deviation (typically -45° to -90°) with
a characteristic qR pattern in lead I and rS pattern in leads II and III. QRS
duration is only mildly prolonged (<120 ms) in isolated LAFB. This combination
is highly specific and distinguishes LAFB from inferior MI or LVH as causes of left
axis deviation.
Question 11 [True/False]
True or False: On certifying exams, ST segment depression in leads V1–V3
may represent a true posterior wall myocardial infarction.
Correct Answer: True
Rationale: Posterior MI produces ST depression (not elevation) in the anterior
leads V1–V3 because these leads are electrically opposite to the posterior wall.
This is a classic certifying exam dilemma. Posterior MI should be suspected when
,The Complete Guide to ECGs — Complete Test Bank
anterior ST depression is accompanied by tall, broad R waves and upright T
waves in V1–V2 — essentially a 'mirror image' of an anterior STEMI.
Question 12 [Multiple Choice]
On a certifying exam, you must interpret a 12-lead ECG with no P waves and
an irregularly irregular rhythm. What is the most likely diagnosis?
A. Sinus arrhythmia
B. Third-degree AV block
C. Atrial fibrillation
D. Multifocal atrial tachycardia
Correct Answer: C. Atrial fibrillation
Rationale: Atrial fibrillation is characterized by the absence of discrete P waves
(replaced by fibrillatory baseline), an irregularly irregular ventricular response,
and narrow QRS complexes (unless aberrant conduction is present). This
combination is pathognomonic for AF and is one of the highest-yield rhythms on
all cardiology certifying exams.
Question 13 [Multiple Choice]
Which of the following ECG findings is most suggestive of hyperkalemia, a
condition frequently tested on certifying exams?
A. Short QT interval with J waves
B. Prolonged PR interval with delta waves
C. Tall, narrow, peaked T waves with widening QRS
D. ST elevation in aVR with global ST depression
Correct Answer: C. Tall, narrow, peaked T waves with widening QRS
Rationale: Hyperkalemia produces a sequential progression of ECG changes.
Early changes include tall, narrow, symmetric (peaked/tent-shaped) T waves. As
potassium rises, PR prolongation and QRS widening occur. Severe hyperkalemia
, The Complete Guide to ECGs — Complete Test Bank
can lead to a sine-wave pattern and cardiac arrest. This progression is a high-
yield topic for all cardiology and internal medicine boards.
Question 14 [True/False]
True or False: Sinus arrhythmia is a pathological finding that requires further
workup when identified on a certifying exam ECG.
Correct Answer: False
Rationale: Sinus arrhythmia — a variation in heart rate with respiration (rate
increases with inspiration, decreases with expiration) — is a normal
physiological finding, particularly in young adults and athletes. The P wave
morphology remains normal and the PR interval is consistent. On certifying
exams, sinus arrhythmia should be identified as a normal variant, not a
pathological condition requiring further evaluation.
Question 15 [Multiple Choice]
A certifying exam ECG shows a regular narrow-complex tachycardia at 150
bpm. What is the most important diagnosis to consider?
A. Sinus tachycardia
B. Atrial flutter with 2:1 conduction
C. AV nodal reentrant tachycardia
D. Junctional tachycardia
Correct Answer: B. Atrial flutter with 2:1 conduction
Rationale: Atrial flutter classically produces an atrial rate of ~300 bpm with
2:1 AV conduction, resulting in a ventricular rate of ~150 bpm. This is one of the
most commonly missed diagnoses on certifying exams because flutter waves may
be hidden in QRS complexes or T waves. When a regular tachycardia presents at
exactly 150 bpm, atrial flutter should always be the first consideration.
Question 16 [Multiple Choice]
