Which statement explains why known obstructive left main coronary artery stenosis is treated as a relative contraindication?

Which statement explains why known obstructive left main coronary artery stenosis is treated as a relative contraindication?

• A. It is an absolute contraindication
• B. It indicates no risk during testing
• C. It poses no risk of ischemia
• D. A large myocardial territory is at risk, increasing the likelihood of severe ischemia during exercise

Answer: (D)

A large portion of the heart muscle depends on the left main artery, so a significant blockage there means exercise-induced stress can cause widespread ischemia. During exercise, the heart’s demand for oxygen increases, but with a critical left main stenosis the blood flow cannot meet that demand across a large territory. That raises the risk of severe ischemia, dangerous arrhythmias, or hemodynamic collapse, making exercise stress testing riskier. Because of this elevated risk, known obstructive left main disease is treated as a relative contraindication, and clinicians often choose pharmacologic stress testing with imaging or proceed to invasive evaluation and revascularization as appropriate.

A large portion of the heart muscle depends on the left main artery, so a significant blockage there means exercise-induced stress can cause widespread ischemia. During exercise, the heart’s demand for oxygen increases, but with a critical left main stenosis the blood flow cannot meet that demand across a large territory. That raises the risk of severe ischemia, dangerous arrhythmias, or hemodynamic collapse, making exercise stress testing riskier. Because of this elevated risk, known obstructive left main disease is treated as a relative contraindication, and clinicians often choose pharmacologic stress testing with imaging or proceed to invasive evaluation and revascularization as appropriate.