In a 50‑year‑old man with typical angina, a family history of sudden cardiac death, and left bundle‑branch block on ECG, what is the most appropriate test to evaluate the coronary arteries?

Pharmacologic Stress Myocardial Perfusion Imaging (Option A)

In this 50-year-old man with typical angina, left bundle-branch block, and a high-risk family history, pharmacologic stress myocardial perfusion imaging is the most appropriate test to assess the coronary arteries. 1, 2

Why Exercise ECG is Contraindicated

• Left bundle-branch block renders exercise ECG uninterpretable because baseline ST-segment abnormalities prevent accurate detection of ischemic ST-segment shifts during stress 1, 2
• The ACC/AHA guidelines explicitly state that in patients with LBBB, exercise ECG should not be used for diagnostic purposes 1, 2
• Exercise-induced tachycardia in LBBB patients produces false-positive septal perfusion defects unrelated to coronary artery disease, with specificity as low as 33% 1

Why Pharmacologic Stress Perfusion is Superior

• Pharmacologic stress testing with vasodilators (adenosine, dipyridamole, or regadenoson) achieves 98% sensitivity, 84% specificity, and 88-92% diagnostic accuracy in LBBB patients 1
• This contrasts sharply with exercise perfusion imaging, which has only 36-60% overall diagnostic accuracy in LBBB 1
• The ACC/AHA and ESC specifically recommend pharmacologic stress myocardial perfusion imaging for patients with uninterpretable ECGs due to LBBB 1, 2
• Vasodilator stress avoids the false-positive septal defects that occur with exercise or dobutamine in LBBB patients 1

Why CT Angiography is Inappropriate

• CT angiography does not assess the functional significance of coronary stenoses or detect myocardial ischemia, which is critical in this symptomatic patient 2
• CT angiography is more appropriate for ruling out disease in low-to-intermediate risk patients, not for functional assessment in symptomatic high-risk patients 2
• This patient requires functional assessment of ischemia, not just anatomical visualization 2

Why Calcium Scoring CT is Inadequate

• Calcium scoring CT has only ~40% specificity for detecting hemodynamically significant coronary stenosis in symptomatic individuals 2
• The ACC advises against using calcium scoring as a screening tool for coronary artery disease due to poor specificity 2
• Calcium scoring quantifies plaque burden but does not evaluate whether stenoses cause ischemia, making it unsuitable for this symptomatic patient with typical angina 2

High-Risk Features Requiring Urgent Evaluation

• This patient's combination of typical angina, LBBB, and family history of premature sudden cardiac death (brother died at age 46) classifies him as high-risk 2
• High-risk patients with typical angina warrant prompt functional evaluation rather than delayed or anatomical-only testing 2
• If pharmacologic perfusion imaging demonstrates significant ischemia, the patient should proceed directly to invasive coronary angiography for definitive diagnosis and potential revascularization 1, 2

Critical Pitfall to Avoid

• Never order exercise-based testing (exercise ECG or exercise perfusion imaging) in patients with LBBB due to unacceptably high false-positive rates 1, 2
• Always specify vasodilator pharmacologic stress (not dobutamine, which can also produce false-positives in LBBB) when ordering perfusion imaging 1