2026 Paramedic Cardiology Exam Prep:
Practice Questions with Answer Rationales
ECG Interpretation · Dysrhythmias · STEMI
· Cardiac Emergencies · Clinical Scenarios ·
Study Guide
Section 1: ECG Interpretation and Cardiac Anatomy (Questions 1–25)
1. A 12-lead ECG shows ST elevation in leads V1–V4. Which coronary artery
is most likely occluded?
A. Right coronary artery (RCA)
B. Left anterior descending (LAD)
C. Left circumflex (LCx)
D. Left main coronary artery
Answer: B
Rationale: ST elevation in leads V1–V4 indicates an anterior STEMI, which is
most commonly caused by occlusion of the left anterior descending (LAD) artery.
The LAD supplies the anterior wall of the left ventricle, the interventricular
septum, and the apex. Proximal LAD occlusion carries high mortality and is
associated with de Winter's pattern when ST elevation is not present.
2. A 12-lead ECG shows ST elevation in leads II, III, and aVF. Which
coronary artery is most likely occluded?
A. Left anterior descending (LAD)
B. Right coronary artery (RCA)
C. Left circumflex (LCx)
D. Left main coronary artery
Answer: B
,Rationale: ST elevation in leads II, III, and aVF indicates an inferior STEMI. The
right coronary artery (RCA) supplies the inferior wall of the left ventricle in
approximately 80% of people (right-dominant circulation). Reciprocal ST
depression is often seen in leads I and aVL. Inferior STEMI may be complicated
by bradycardia and hypotension if the RCA also supplies the SA and AV nodes.
3. A 12-lead ECG shows ST elevation in leads I, aVL, V5, and V6. Which wall
of the heart is affected?
A. Anterior
B. Inferior
C. Lateral
D. Posterior
Answer: C
Rationale: Leads I, aVL, V5, and V6 view the lateral wall of the left ventricle.
Lateral STEMI is often caused by occlusion of the left circumflex (LCx) artery or a
diagonal branch of the LAD. Reciprocal ST depression may be seen in inferior
leads (II, III, aVF).
4. What is the normal duration of the PR interval on an ECG?
A. 0.04–0.10 seconds
B. 0.12–0.20 seconds
C. 0.20–0.30 seconds
D. 0.30–0.40 seconds
Answer: B
Rationale: The normal PR interval is 0.12–0.20 seconds (3–5 small boxes at
standard paper speed). The PR interval represents the time from the onset of atrial
depolarization to the onset of ventricular depolarization. A PR interval longer than
0.20 seconds indicates first-degree AV block.
5. What is the normal duration of the QRS complex?
,A. Less than 0.08 seconds
B. Less than 0.12 seconds
C. Less than 0.16 seconds
D. Less than 0.20 seconds
Answer: B
Rationale: A normal QRS complex is less than 0.12 seconds (less than 3 small
boxes). A QRS duration of 0.12 seconds or greater indicates a conduction delay,
such as a bundle branch block or ventricular rhythm. Wide QRS complexes are
seen in ventricular tachycardia, PVCs, and bundle branch blocks.
6. A patient's ECG shows a regular rhythm with a rate of 45 beats per minute,
a normal P wave before each QRS, and a PR interval of 0.16 seconds. What is
this rhythm?
A. Sinus bradycardia
B. First-degree AV block
C. Junctional rhythm
D. Second-degree AV block, Type I
Answer: A
Rationale: Sinus bradycardia is characterized by a regular rhythm, rate less than
60 beats per minute, a normal P wave before each QRS, and a normal PR interval
(0.12–0.20 seconds). The sinoatrial (SA) node continues to pace the heart, but at a
slower rate. Treatment is indicated only if the patient is symptomatic.
7. A patient's ECG shows a regular rhythm with a rate of 150 beats per
minute, narrow QRS complexes, and no visible P waves. What is the most
likely rhythm?
A. Sinus tachycardia
B. Supraventricular tachycardia (SVT)
C. Ventricular tachycardia
D. Atrial fibrillation
Answer: B
, Rationale: Supraventricular tachycardia (SVT) typically presents with a regular,
narrow-complex rhythm at a rate of 150–250 beats per minute, with P waves that
are often hidden in the QRS complexes or not visible. The QRS is narrow because
the impulse originates above the ventricles and conducts normally through the His-
Purkinje system.
8. A patient's ECG shows an irregularly irregular rhythm with no discernible
P waves and a variable ventricular rate. What is this rhythm?
A. Atrial flutter
B. Atrial fibrillation
C. Sinus arrhythmia
D. Multifocal atrial tachycardia
Answer: B
Rationale: Atrial fibrillation is characterized by an irregularly irregular ventricular
rhythm, absent P waves, and a chaotic baseline (fibrillatory waves). The atria are
firing at rates of 350–600 impulses per minute, but the AV node blocks most of
these impulses, resulting in an irregular ventricular response.
9. A patient's ECG shows a sawtooth pattern of atrial activity with a
ventricular rate of 150 beats per minute. What is this rhythm?
A. Atrial fibrillation
B. Atrial flutter
C. SVT
D. Sinus tachycardia
Answer: B
Rationale: Atrial flutter is characterized by a sawtooth pattern of atrial activity
(flutter waves) at a rate of 250–350 per minute. The ventricular rate is often a fixed
ratio of the atrial rate (e.g., 2:1 conduction producing a ventricular rate of 150).
The rhythm may be regular or irregular depending on the conduction ratio.
Practice Questions with Answer Rationales
ECG Interpretation · Dysrhythmias · STEMI
· Cardiac Emergencies · Clinical Scenarios ·
Study Guide
Section 1: ECG Interpretation and Cardiac Anatomy (Questions 1–25)
1. A 12-lead ECG shows ST elevation in leads V1–V4. Which coronary artery
is most likely occluded?
A. Right coronary artery (RCA)
B. Left anterior descending (LAD)
C. Left circumflex (LCx)
D. Left main coronary artery
Answer: B
Rationale: ST elevation in leads V1–V4 indicates an anterior STEMI, which is
most commonly caused by occlusion of the left anterior descending (LAD) artery.
The LAD supplies the anterior wall of the left ventricle, the interventricular
septum, and the apex. Proximal LAD occlusion carries high mortality and is
associated with de Winter's pattern when ST elevation is not present.
2. A 12-lead ECG shows ST elevation in leads II, III, and aVF. Which
coronary artery is most likely occluded?
A. Left anterior descending (LAD)
B. Right coronary artery (RCA)
C. Left circumflex (LCx)
D. Left main coronary artery
Answer: B
,Rationale: ST elevation in leads II, III, and aVF indicates an inferior STEMI. The
right coronary artery (RCA) supplies the inferior wall of the left ventricle in
approximately 80% of people (right-dominant circulation). Reciprocal ST
depression is often seen in leads I and aVL. Inferior STEMI may be complicated
by bradycardia and hypotension if the RCA also supplies the SA and AV nodes.
3. A 12-lead ECG shows ST elevation in leads I, aVL, V5, and V6. Which wall
of the heart is affected?
A. Anterior
B. Inferior
C. Lateral
D. Posterior
Answer: C
Rationale: Leads I, aVL, V5, and V6 view the lateral wall of the left ventricle.
Lateral STEMI is often caused by occlusion of the left circumflex (LCx) artery or a
diagonal branch of the LAD. Reciprocal ST depression may be seen in inferior
leads (II, III, aVF).
4. What is the normal duration of the PR interval on an ECG?
A. 0.04–0.10 seconds
B. 0.12–0.20 seconds
C. 0.20–0.30 seconds
D. 0.30–0.40 seconds
Answer: B
Rationale: The normal PR interval is 0.12–0.20 seconds (3–5 small boxes at
standard paper speed). The PR interval represents the time from the onset of atrial
depolarization to the onset of ventricular depolarization. A PR interval longer than
0.20 seconds indicates first-degree AV block.
5. What is the normal duration of the QRS complex?
,A. Less than 0.08 seconds
B. Less than 0.12 seconds
C. Less than 0.16 seconds
D. Less than 0.20 seconds
Answer: B
Rationale: A normal QRS complex is less than 0.12 seconds (less than 3 small
boxes). A QRS duration of 0.12 seconds or greater indicates a conduction delay,
such as a bundle branch block or ventricular rhythm. Wide QRS complexes are
seen in ventricular tachycardia, PVCs, and bundle branch blocks.
6. A patient's ECG shows a regular rhythm with a rate of 45 beats per minute,
a normal P wave before each QRS, and a PR interval of 0.16 seconds. What is
this rhythm?
A. Sinus bradycardia
B. First-degree AV block
C. Junctional rhythm
D. Second-degree AV block, Type I
Answer: A
Rationale: Sinus bradycardia is characterized by a regular rhythm, rate less than
60 beats per minute, a normal P wave before each QRS, and a normal PR interval
(0.12–0.20 seconds). The sinoatrial (SA) node continues to pace the heart, but at a
slower rate. Treatment is indicated only if the patient is symptomatic.
7. A patient's ECG shows a regular rhythm with a rate of 150 beats per
minute, narrow QRS complexes, and no visible P waves. What is the most
likely rhythm?
A. Sinus tachycardia
B. Supraventricular tachycardia (SVT)
C. Ventricular tachycardia
D. Atrial fibrillation
Answer: B
, Rationale: Supraventricular tachycardia (SVT) typically presents with a regular,
narrow-complex rhythm at a rate of 150–250 beats per minute, with P waves that
are often hidden in the QRS complexes or not visible. The QRS is narrow because
the impulse originates above the ventricles and conducts normally through the His-
Purkinje system.
8. A patient's ECG shows an irregularly irregular rhythm with no discernible
P waves and a variable ventricular rate. What is this rhythm?
A. Atrial flutter
B. Atrial fibrillation
C. Sinus arrhythmia
D. Multifocal atrial tachycardia
Answer: B
Rationale: Atrial fibrillation is characterized by an irregularly irregular ventricular
rhythm, absent P waves, and a chaotic baseline (fibrillatory waves). The atria are
firing at rates of 350–600 impulses per minute, but the AV node blocks most of
these impulses, resulting in an irregular ventricular response.
9. A patient's ECG shows a sawtooth pattern of atrial activity with a
ventricular rate of 150 beats per minute. What is this rhythm?
A. Atrial fibrillation
B. Atrial flutter
C. SVT
D. Sinus tachycardia
Answer: B
Rationale: Atrial flutter is characterized by a sawtooth pattern of atrial activity
(flutter waves) at a rate of 250–350 per minute. The ventricular rate is often a fixed
ratio of the atrial rate (e.g., 2:1 conduction producing a ventricular rate of 150).
The rhythm may be regular or irregular depending on the conduction ratio.
