Dangers of left main coronary artery lesions: angiographic technique and evaluation

Five hundred consecutive coronary arteriograms were reviewed to evaluate left main coronary artery lesions. This entity has been associated with a high incidence of angiographic deaths. Clinical signs claimed to be diagnostic were analyzed together with the value of various projections for making the diagnosis. Pressure damping was a vital sign, and when persistent, it required 3-5 mm to be cut from the catheter's tip for a safe study to be performed. Shallow 10-15 degrees oblique and AP projections were found to be essential for a complete evaluation of the left main trunk. Marked ST depression or hypotension during treadmill exercise testing, as well as the presence of coronary calcification were not statistically significant in anticipating this lesion. The incidence of left main lesions nearly 15% (74/500) in this series is higher than previously reported (2.4-5.9%); however, in 8% (40/500), the stenosis was 75% or greater in degree which more closely approximates to the incidence previously reported in the literature. This may be the result of the additional projections recommended, but is probably also related to the population studied. No complications occurred in this series.