DOES IT MATTER HOW CORONARY PROJECTIONS ARE COMBINED TO ASSESS RESTENOSIS FOLLOWING PTCA

Three methods were used to combine measurements from biplane coronary views to assess restenosis following PTCA. The first 153 patients from the EMPAR trial with 118 measurable coronary stenoses were chosen for this study. The mean difference between the RAO and LAO projections u sed was 88 +/- 22 degrees (S.D.). There was no systematic difference i n coronary dimensions between RAO and LAO views for the group. Coronar y restenosis was primarily defined as loss of 50% or more of the lumin al diameter gain from the procedure. The ratio of luminal loss to gain was calculated for each stenosis using (Method 1) only the lesser dia meter of the two views, (Method 2) an average of the two views and, (M ethod 3) a calculated cross-sectional coronary lumen area. Rates of re stenosis calculated in this way ranged between 36 and 44% amongst the three methods, which was not significantly different. However, individ ual coronary lesions might be classified as either restenosed or not b y this formula, depending on which method was used to integrate the bi plane coronary measurements.