Objective: To review the diagnosis and management of noncritical left main stem disease.
Data sources: MEDLINE was searched using the key phrases 'intravascular ultrasound' and 'left main coronary artery'.
Data extraction: Articles addressing the angiographic or ultrasound assessment of left main stem disease were systematically reviewed. Reference is also made to articles dealing with outcomes for patients with left main stem disease.
Data synthesis: The assessment of left main stem disease by coronary angiography is often suboptimal. Intravascular ultrasound has demonstrated significant left main stem disease in angiographically normal arteries. It has also demonstrated that mild to moderate left main stem disease frequently accompanies disease in the other coronary arteries. The natural history of mild to moderate left main stem disease has not been well characterized; thus, the optimum management of this condition is not known.
Conclusions: To establish the natural history of noncritical left main stem stenosis, it is proposed that centres performing frequent intravascular ultrasound examinations systematically and quantitatively interrogate the left main stem during all left coronary examinations. Angiographic and ultrasonic measures of left main stem disease can then be correlated with clinical outcome during long term follow-up. This will clearly require the collaboration of several centres to generate a sufficiently large database to address these clinical questions.