What is the most appropriate test to assess the coronary arteries in a patient with recurrent chest tightness, a family history of sudden death, and left bundle branch block on electrocardiogram (ECG)?

Myocardial Perfusion Imaging (Stress SPECT/PET) is the Most Appropriate Test

In a 50-year-old male with recurrent exertional chest pain, family history of sudden death, and left bundle branch block (LBBB) on ECG, myocardial perfusion imaging with pharmacological stress is the most appropriate test to assess the coronary arteries.

Rationale for Myocardial Perfusion Imaging

LBBB Makes Exercise ECG Non-Interpretable

• LBBB renders the resting ECG uninterpretable for ischemia, which eliminates exercise ECG as a diagnostic option 1
• The 2024 ESC guidelines explicitly state that exercise ECG is not recommended for diagnostic purposes in patients with left bundle branch block 1
• Baseline ST-segment abnormalities from LBBB interfere with interpretation of ST-segment shifts during stress testing 1

Functional Assessment is Critical in This Clinical Context

• This patient presents with typical angina (substernal chest tightness, provoked by exertion, relieved by rest within 4 minutes), placing him at intermediate-to-high pre-test probability for obstructive coronary artery disease 1
• The strong family history of sudden death at age 46 further elevates his risk profile and necessitates functional assessment of myocardial ischemia 1
• Pharmacological stress myocardial perfusion imaging (SPECT or PET) is specifically recommended for patients unable to exercise or with uninterpretable ECGs 1

Why Not the Other Options?

Exercise ECG (Option C) is contraindicated because LBBB makes ST-segment analysis impossible 1

Calcium CT (Option D) only provides anatomic information about calcified plaque burden but does not assess hemodynamic significance of stenoses or detect myocardial ischemia 1, 2. A high calcium score would not tell you if his symptoms are due to flow-limiting disease.

CT Angiography (Option B) has significant limitations in this scenario:

• While CT angiography can visualize coronary anatomy, it does not directly assess the functional significance of stenoses 3, 2
• Patients with high calcium scores (likely in someone with a strong family history) have reduced diagnostic accuracy with CT angiography 4
• CT angiography is more appropriate for ruling out disease in low-to-intermediate risk patients, not for functional assessment in symptomatic high-risk patients 1

Clinical Algorithm

For this patient with LBBB and typical angina:

1. Perform pharmacological stress myocardial perfusion imaging (adenosine or regadenoson SPECT, or rubidium-82 PET) as the initial non-invasive test 1

2. If perfusion imaging shows significant ischemia (large or multiple perfusion defects), proceed directly to invasive coronary angiography for definitive diagnosis and potential revascularization 1, 5

3. If perfusion imaging is negative or equivocal but symptoms persist, consider CT angiography as a complementary anatomic test or proceed to invasive angiography given the high-risk features 1

Important Caveats

• Do not delay definitive evaluation in this patient—the combination of typical angina, LBBB, and strong family history of premature sudden death represents a high-risk phenotype 1, 5
• If the patient develops acute symptoms or hemodynamic instability, bypass non-invasive testing entirely and proceed directly to invasive coronary angiography 5
• LBBB itself can cause septal perfusion abnormalities on nuclear imaging (false positives), so use vasodilator stress (not dobutamine) and consider PET over SPECT for better specificity 1

Answer: A - Myocardial perfusion imaging