COMSAE Phase 1 Form 116 Practice Exam
Questions And Correct Answers (Verified
Answers) Plus Rationales 2025|2026 Q&A |
Instant Download Pdf
Question 1
A 58-year-old man presents with chest pain radiating to his left arm. ECG shows
ST elevation in leads II, III, and aVF. Which coronary artery is most likely
occluded?
A) Left anterior descending artery
B) Right coronary artery
C) Left circumflex artery
D) Posterior descending artery
Rationale & Explanation:
ST elevation in leads II, III, and aVF indicates an inferior wall myocardial
infarction . The right coronary artery (RCA) supplies the inferior wall of the heart
in approximately 80% of individuals (right-dominant circulation). The RCA also
supplies the AV node in 90% of people, which explains why inferior MIs are often
accompanied by bradycardia or heart block. The LAD supplies the anterior wall
(V1-V4), and the LCx supplies the lateral wall (I, aVL, V5-V6).
Question 2
A 65-year-old man with a history of hypertension presents with sudden onset of
severe, tearing chest pain radiating to the back. His blood pressure is 190/100
mmHg in the right arm and 110/70 mmHg in the left arm. ECG shows no ST-
segment elevation. What is the most appropriate next diagnostic test?
,A) Transthoracic echocardiogram
B) CT angiography of the chest
C) Coronary angiography
D) Chest X-ray
Rationale & Explanation:
This patient presents with classic findings of aortic dissection – tearing chest pain
radiating to the back with a blood pressure differential between arms . CT
angiography of the chest is the study of choice for diagnosing aortic dissection
because it can rapidly identify the intimal flap, determine the extent of the
dissection (Stanford Type A vs. Type B), and identify involvement of branch
vessels. Transthoracic echocardiography has lower sensitivity for aortic dissection.
Coronary angiography is for suspected MI. Chest X-ray may show a widened
mediastinum but is not diagnostic.
Question 3
A 72-year-old woman with atrial fibrillation presents with sudden onset of severe
pain in her right leg. On examination, the right leg is pale, cold to the touch, and
pulseless. She reports paresthesias and is unable to move her toes. What is the most
likely diagnosis?
A) Deep vein thrombosis
B) Acute arterial embolism
C) Cellulitis
D) Neuropathy
Rationale & Explanation:
This patient presents with the five P's of acute limb ischemia: Pain, Pallor,
Pulselessness, Paresthesia, and Paralysis . In a patient with atrial fibrillation, the
most common source is a cardioembolic event (thrombus from the left atrium or
left atrial appendage embolizing to the femoral or popliteal artery). This is a
surgical emergency requiring emergent embolectomy or thrombolysis to prevent
limb loss. DVT presents with swelling, warmth, and pain but not pallor or
pulselessness.
,Question 4
A 45-year-old man presents with an episode of syncope lasting less than 1 minute.
He has a pacemaker. No tongue biting or urinary incontinence. What is the most
likely cause of his syncope?
A) Vasovagal syncope
B) Idioventricular rhythm due to pacemaker failure
C) Seizure
D) Orthostatic hypotension
Rationale & Explanation:
In a patient with a pacemaker, syncope is most likely due to pacemaker
failure leading to an idioventricular escape rhythm (20-40 bpm) causing a
sudden drop in cerebral perfusion. Pacemaker failure can result from battery
depletion, lead fracture, lead dislodgement, or failure to capture. The rapid
recovery (<1 minute) and absence of seizure features (tongue biting, incontinence)
support cardiac syncope over seizure. Vasovagal syncope typically has a prodrome
(nausea, sweating, lightheadedness), and orthostatic hypotension would have
positional symptoms.
Question 5
A patient develops infective endocarditis after dental work. Which organism
commonly causes subacute disease on abnormal valves?
A) Staphylococcus aureus
B) Streptococcus viridans
C) Enterococcus faecalis
D) Pseudomonas aeruginosa
Rationale & Explanation:
Streptococcus viridans (part of the normal oral flora) is the most common cause
of subacute bacterial endocarditis on previously abnormal or damaged valves .
These organisms have low virulence and typically require a pre-existing valvular
abnormality (e.g., rheumatic heart disease, bicuspid aortic valve, mitral valve
, prolapse) or prosthetic valve to establish infection. In contrast, Staphylococcus
aureus causes acute endocarditis on normal valves, often with a more fulminant
course. Prophylactic antibiotics before dental procedures are recommended for
patients with highest-risk cardiac conditions.
Question 6
A systolic crescendo-decrescendo murmur radiating to the carotids is heard in an
elderly patient. Which valvular lesion is most likely present?
A) Mitral stenosis
B) Mitral regurgitation
C) Aortic stenosis
D) Aortic regurgitation
Rationale & Explanation:
Aortic stenosis produces a crescendo-decrescendo (ejection) systolic
murmur best heard at the right upper sternal border (aortic area) with radiation to
the carotid arteries . In elderly patients, the most common cause is calcific
degeneration of a tricuspid or bicuspid aortic valve. Classic symptoms of severe
aortic stenosis include angina, syncope, and dyspnea on exertion. Mitral
regurgitation produces a holosystolic murmur at the apex radiating to the axilla.
Aortic regurgitation produces a diastolic decrescendo murmur.
Question 7
A patient with chronic heart failure presents with progressive dyspnea, orthopnea,
and peripheral edema. Which two factors influence the Starling curve?
A) Afterload and contractility
B) Heart rate and afterload
C) Preload (EDV) on x-axis and stroke volume on y-axis
D) Contractility and preload
Rationale & Explanation:
The Frank-Starling curve plots preload (end-diastolic volume) on the x-axis
Questions And Correct Answers (Verified
Answers) Plus Rationales 2025|2026 Q&A |
Instant Download Pdf
Question 1
A 58-year-old man presents with chest pain radiating to his left arm. ECG shows
ST elevation in leads II, III, and aVF. Which coronary artery is most likely
occluded?
A) Left anterior descending artery
B) Right coronary artery
C) Left circumflex artery
D) Posterior descending artery
Rationale & Explanation:
ST elevation in leads II, III, and aVF indicates an inferior wall myocardial
infarction . The right coronary artery (RCA) supplies the inferior wall of the heart
in approximately 80% of individuals (right-dominant circulation). The RCA also
supplies the AV node in 90% of people, which explains why inferior MIs are often
accompanied by bradycardia or heart block. The LAD supplies the anterior wall
(V1-V4), and the LCx supplies the lateral wall (I, aVL, V5-V6).
Question 2
A 65-year-old man with a history of hypertension presents with sudden onset of
severe, tearing chest pain radiating to the back. His blood pressure is 190/100
mmHg in the right arm and 110/70 mmHg in the left arm. ECG shows no ST-
segment elevation. What is the most appropriate next diagnostic test?
,A) Transthoracic echocardiogram
B) CT angiography of the chest
C) Coronary angiography
D) Chest X-ray
Rationale & Explanation:
This patient presents with classic findings of aortic dissection – tearing chest pain
radiating to the back with a blood pressure differential between arms . CT
angiography of the chest is the study of choice for diagnosing aortic dissection
because it can rapidly identify the intimal flap, determine the extent of the
dissection (Stanford Type A vs. Type B), and identify involvement of branch
vessels. Transthoracic echocardiography has lower sensitivity for aortic dissection.
Coronary angiography is for suspected MI. Chest X-ray may show a widened
mediastinum but is not diagnostic.
Question 3
A 72-year-old woman with atrial fibrillation presents with sudden onset of severe
pain in her right leg. On examination, the right leg is pale, cold to the touch, and
pulseless. She reports paresthesias and is unable to move her toes. What is the most
likely diagnosis?
A) Deep vein thrombosis
B) Acute arterial embolism
C) Cellulitis
D) Neuropathy
Rationale & Explanation:
This patient presents with the five P's of acute limb ischemia: Pain, Pallor,
Pulselessness, Paresthesia, and Paralysis . In a patient with atrial fibrillation, the
most common source is a cardioembolic event (thrombus from the left atrium or
left atrial appendage embolizing to the femoral or popliteal artery). This is a
surgical emergency requiring emergent embolectomy or thrombolysis to prevent
limb loss. DVT presents with swelling, warmth, and pain but not pallor or
pulselessness.
,Question 4
A 45-year-old man presents with an episode of syncope lasting less than 1 minute.
He has a pacemaker. No tongue biting or urinary incontinence. What is the most
likely cause of his syncope?
A) Vasovagal syncope
B) Idioventricular rhythm due to pacemaker failure
C) Seizure
D) Orthostatic hypotension
Rationale & Explanation:
In a patient with a pacemaker, syncope is most likely due to pacemaker
failure leading to an idioventricular escape rhythm (20-40 bpm) causing a
sudden drop in cerebral perfusion. Pacemaker failure can result from battery
depletion, lead fracture, lead dislodgement, or failure to capture. The rapid
recovery (<1 minute) and absence of seizure features (tongue biting, incontinence)
support cardiac syncope over seizure. Vasovagal syncope typically has a prodrome
(nausea, sweating, lightheadedness), and orthostatic hypotension would have
positional symptoms.
Question 5
A patient develops infective endocarditis after dental work. Which organism
commonly causes subacute disease on abnormal valves?
A) Staphylococcus aureus
B) Streptococcus viridans
C) Enterococcus faecalis
D) Pseudomonas aeruginosa
Rationale & Explanation:
Streptococcus viridans (part of the normal oral flora) is the most common cause
of subacute bacterial endocarditis on previously abnormal or damaged valves .
These organisms have low virulence and typically require a pre-existing valvular
abnormality (e.g., rheumatic heart disease, bicuspid aortic valve, mitral valve
, prolapse) or prosthetic valve to establish infection. In contrast, Staphylococcus
aureus causes acute endocarditis on normal valves, often with a more fulminant
course. Prophylactic antibiotics before dental procedures are recommended for
patients with highest-risk cardiac conditions.
Question 6
A systolic crescendo-decrescendo murmur radiating to the carotids is heard in an
elderly patient. Which valvular lesion is most likely present?
A) Mitral stenosis
B) Mitral regurgitation
C) Aortic stenosis
D) Aortic regurgitation
Rationale & Explanation:
Aortic stenosis produces a crescendo-decrescendo (ejection) systolic
murmur best heard at the right upper sternal border (aortic area) with radiation to
the carotid arteries . In elderly patients, the most common cause is calcific
degeneration of a tricuspid or bicuspid aortic valve. Classic symptoms of severe
aortic stenosis include angina, syncope, and dyspnea on exertion. Mitral
regurgitation produces a holosystolic murmur at the apex radiating to the axilla.
Aortic regurgitation produces a diastolic decrescendo murmur.
Question 7
A patient with chronic heart failure presents with progressive dyspnea, orthopnea,
and peripheral edema. Which two factors influence the Starling curve?
A) Afterload and contractility
B) Heart rate and afterload
C) Preload (EDV) on x-axis and stroke volume on y-axis
D) Contractility and preload
Rationale & Explanation:
The Frank-Starling curve plots preload (end-diastolic volume) on the x-axis
