[HOAG ECG EXAM] – EXAM-STYLE QUESTIONS AND ANSWERS | VERIFIED AND
WELL DETAILED ANSWERS | PLUS RATIONALES | GUARANTEED PASS | 2026/27
LATEST UPDATE | EXAM PREP | STUDY GUIDE | PRACTICE TEST
SECTION ONE: QUESTIONS 1-50
1. A 68-year-old patient presents with acute-onset chest pain and diaphoresis.
The 12-lead ECG shows 2-mm ST-segment elevations in leads V1 through V4.
Which of the following is the most appropriate immediate next step in
management?
A. Administer sublingual nitroglycerin and monitor for relief.
B. Obtain a chest radiograph to rule out aortic dissection.
C. Initiate the acute myocardial infarction protocol and prepare for possible
percutaneous coronary intervention.
D. Order a transthoracic echocardiogram to assess for regional wall motion
abnormalities.
Correct Answer: C. Initiate the acute myocardial infarction protocol and prepare
for possible percutaneous coronary intervention.
Rationale: The ECG findings of ST-segment elevation in the anterior precordial
leads (V1-V4) are indicative of an acute anterior ST-segment elevation myocardial
infarction (STEMI). The standard of care for a STEMI is urgent reperfusion therapy,
most commonly via primary percutaneous coronary intervention (PCI). The priority
is to activate the catheterization lab and initiate the STEMI protocol to minimize
time to reperfusion. While the other options may be part of a broader evaluation,
they should not delay the definitive treatment protocol. Administering nitroglycerin
without a protocol and prior to assessing right ventricular involvement could be
,risky, and imaging studies, while potentially useful, would cause a critical delay in
reperfusion.
2. When interpreting a 12-lead ECG, the electrical axis of the heart in the frontal
plane is determined primarily by analyzing which of the following leads?
A. Leads V1 and V6
B. Leads I, II, and III
C. Leads aVR, aVL, and aVF
D. Leads I and aVF
Correct Answer: D. Leads I and aVF.
Rationale: The frontal plane axis is derived from the limb leads. Leads I and aVF are
perpendicular to each other and are used as the primary reference leads for a quick
and accurate determination of the mean QRS axis. An axis that is positive in both
lead I and lead aVF indicates a normal axis (0° to +90°). While leads II and III, or I,
II, and III, can be used, the combination of leads I and aVF is the most direct method
for this assessment. The precordial leads (V1-V6) assess the horizontal plane.
3. A 55-year-old patient's ECG reveals a regular rhythm with a rate of 42 beats
per minute. The P waves are upright and consistent in morphology, and each P
wave is followed by a QRS complex. What is the most likely diagnosis?
A. Sinus arrhythmia
B. Sinus bradycardia
C. First-degree atrioventricular block
D. Junctional escape rhythm
Correct Answer: B. Sinus bradycardia.
,Rationale: The rhythm originates from the sinoatrial (SA) node, as evidenced by
consistent, upright P waves. A rate of 42 bpm is below the normal range of 60-100
bpm, which defines sinus bradycardia. Sinus arrhythmia would involve an irregular
rhythm. First-degree AV block would show a prolonged PR interval. A junctional
rhythm would either lack P waves or show inverted P waves preceding or following
the QRS complex, and the rate would typically be 40-60 bpm.
4. A patient's ECG shows a prolonged PR interval of 0.28 seconds. All other
intervals and morphology are normal. Which of the following conditions does
this ECG finding most likely indicate?
A. Second-degree AV block, Mobitz type I
B. First-degree atrioventricular block
C. Left bundle branch block
D. Hyperkalemia
Correct Answer: B. First-degree atrioventricular block.
Rationale: A first-degree AV block is defined by a PR interval exceeding 0.20
seconds (200 milliseconds). It represents a delay in conduction from the atria to the
ventricles, typically at the level of the AV node. The other options present with
different ECG characteristics: Mobitz type I (Wenckebach) shows progressive PR
prolongation culminating in a dropped beat, a left bundle branch block presents
with a wide QRS complex and a characteristic morphology, and hyperkalemia
presents with peaked T waves and a widened QRS complex.
5. A 72-year-old patient with a history of hypertension presents for a routine
ECG. Her rhythm is regular with a rate of 88 bpm. The QRS complex duration is
0.10 seconds, and the PR interval is 0.18 seconds. The ECG shows a Q wave in
, lead III and aVF that is >0.04 seconds wide and >25% of the height of the R
wave. What is the most appropriate interpretation of this finding?
A. A normal variant, requiring no further investigation.
B. An indication of a prior inferior wall myocardial infarction.
C. A sign of left ventricular hypertrophy.
D. A manifestation of a bundle branch block.
Correct Answer: B. An indication of a prior inferior wall myocardial infarction.
Rationale: Pathological Q waves, defined as being ≥0.04 seconds wide and/or
having a depth >25% of the corresponding R wave height, are indicative of
myocardial necrosis. Their presence in the inferior leads (II, III, and aVF) points to a
prior inferior wall infarction. This is not a normal variant and warrants clinical
correlation. Left ventricular hypertrophy would demonstrate high voltage QRS
complexes and ST-T wave changes. A bundle branch block would manifest as a
widened QRS complex.
6. Which of the following ECG findings is most characteristic of hypokalemia?
A. Tall, peaked T waves
B. Prolonged QT interval
C. Presence of a U wave
D. ST-segment elevation
Correct Answer: C. Presence of a U wave.
Rationale: The presence of a U wave, a small deflection following the T wave, is a
classic ECG sign of hypokalemia. This finding is often accompanied by flattening or
inversion of the T wave. Tall, peaked T waves are characteristic of hyperkalemia. A
WELL DETAILED ANSWERS | PLUS RATIONALES | GUARANTEED PASS | 2026/27
LATEST UPDATE | EXAM PREP | STUDY GUIDE | PRACTICE TEST
SECTION ONE: QUESTIONS 1-50
1. A 68-year-old patient presents with acute-onset chest pain and diaphoresis.
The 12-lead ECG shows 2-mm ST-segment elevations in leads V1 through V4.
Which of the following is the most appropriate immediate next step in
management?
A. Administer sublingual nitroglycerin and monitor for relief.
B. Obtain a chest radiograph to rule out aortic dissection.
C. Initiate the acute myocardial infarction protocol and prepare for possible
percutaneous coronary intervention.
D. Order a transthoracic echocardiogram to assess for regional wall motion
abnormalities.
Correct Answer: C. Initiate the acute myocardial infarction protocol and prepare
for possible percutaneous coronary intervention.
Rationale: The ECG findings of ST-segment elevation in the anterior precordial
leads (V1-V4) are indicative of an acute anterior ST-segment elevation myocardial
infarction (STEMI). The standard of care for a STEMI is urgent reperfusion therapy,
most commonly via primary percutaneous coronary intervention (PCI). The priority
is to activate the catheterization lab and initiate the STEMI protocol to minimize
time to reperfusion. While the other options may be part of a broader evaluation,
they should not delay the definitive treatment protocol. Administering nitroglycerin
without a protocol and prior to assessing right ventricular involvement could be
,risky, and imaging studies, while potentially useful, would cause a critical delay in
reperfusion.
2. When interpreting a 12-lead ECG, the electrical axis of the heart in the frontal
plane is determined primarily by analyzing which of the following leads?
A. Leads V1 and V6
B. Leads I, II, and III
C. Leads aVR, aVL, and aVF
D. Leads I and aVF
Correct Answer: D. Leads I and aVF.
Rationale: The frontal plane axis is derived from the limb leads. Leads I and aVF are
perpendicular to each other and are used as the primary reference leads for a quick
and accurate determination of the mean QRS axis. An axis that is positive in both
lead I and lead aVF indicates a normal axis (0° to +90°). While leads II and III, or I,
II, and III, can be used, the combination of leads I and aVF is the most direct method
for this assessment. The precordial leads (V1-V6) assess the horizontal plane.
3. A 55-year-old patient's ECG reveals a regular rhythm with a rate of 42 beats
per minute. The P waves are upright and consistent in morphology, and each P
wave is followed by a QRS complex. What is the most likely diagnosis?
A. Sinus arrhythmia
B. Sinus bradycardia
C. First-degree atrioventricular block
D. Junctional escape rhythm
Correct Answer: B. Sinus bradycardia.
,Rationale: The rhythm originates from the sinoatrial (SA) node, as evidenced by
consistent, upright P waves. A rate of 42 bpm is below the normal range of 60-100
bpm, which defines sinus bradycardia. Sinus arrhythmia would involve an irregular
rhythm. First-degree AV block would show a prolonged PR interval. A junctional
rhythm would either lack P waves or show inverted P waves preceding or following
the QRS complex, and the rate would typically be 40-60 bpm.
4. A patient's ECG shows a prolonged PR interval of 0.28 seconds. All other
intervals and morphology are normal. Which of the following conditions does
this ECG finding most likely indicate?
A. Second-degree AV block, Mobitz type I
B. First-degree atrioventricular block
C. Left bundle branch block
D. Hyperkalemia
Correct Answer: B. First-degree atrioventricular block.
Rationale: A first-degree AV block is defined by a PR interval exceeding 0.20
seconds (200 milliseconds). It represents a delay in conduction from the atria to the
ventricles, typically at the level of the AV node. The other options present with
different ECG characteristics: Mobitz type I (Wenckebach) shows progressive PR
prolongation culminating in a dropped beat, a left bundle branch block presents
with a wide QRS complex and a characteristic morphology, and hyperkalemia
presents with peaked T waves and a widened QRS complex.
5. A 72-year-old patient with a history of hypertension presents for a routine
ECG. Her rhythm is regular with a rate of 88 bpm. The QRS complex duration is
0.10 seconds, and the PR interval is 0.18 seconds. The ECG shows a Q wave in
, lead III and aVF that is >0.04 seconds wide and >25% of the height of the R
wave. What is the most appropriate interpretation of this finding?
A. A normal variant, requiring no further investigation.
B. An indication of a prior inferior wall myocardial infarction.
C. A sign of left ventricular hypertrophy.
D. A manifestation of a bundle branch block.
Correct Answer: B. An indication of a prior inferior wall myocardial infarction.
Rationale: Pathological Q waves, defined as being ≥0.04 seconds wide and/or
having a depth >25% of the corresponding R wave height, are indicative of
myocardial necrosis. Their presence in the inferior leads (II, III, and aVF) points to a
prior inferior wall infarction. This is not a normal variant and warrants clinical
correlation. Left ventricular hypertrophy would demonstrate high voltage QRS
complexes and ST-T wave changes. A bundle branch block would manifest as a
widened QRS complex.
6. Which of the following ECG findings is most characteristic of hypokalemia?
A. Tall, peaked T waves
B. Prolonged QT interval
C. Presence of a U wave
D. ST-segment elevation
Correct Answer: C. Presence of a U wave.
Rationale: The presence of a U wave, a small deflection following the T wave, is a
classic ECG sign of hypokalemia. This finding is often accompanied by flattening or
inversion of the T wave. Tall, peaked T waves are characteristic of hyperkalemia. A
