An anatomic variant of left anterior descending coronary artery (LAD), termed "dual LAD", consists of early bifurcation of the proximal LAD into one early terminating branch (short LAD) which remains in the anterior interventricular sulcus (AIVS) and doesn't reach the apex, and the second (long LAD), which has a variable course outside the AIVS but returns to the distal sulcus and continues to the apex. Its incidence, angiographic features and clinical significance are investigated.

Consecutive 696 coronary angiograms during October 1997 through August 1998 were analyzed.

A dual LAD variant was noted in 45 patients (6%) of the 696 patients. Type I, in which the long LAD descends on the left ventricular side of the AIVS before reentering the AIVS, was noted in 24 patients (53%) and type II, in which the long LAD descends on the right ventricular side of the AIVS before reentering the AIVS, in 21(47%). First septal branch was commonly originated from LAD proper in both type (54% vs 52%), but first diagonal branch from LAD proper (63%) in type I, from short LAD (71%) in type II. Presence of dual LAD was recognized before percutaneous coronary intervention (10) or bypass surgery (2) in 12 (63%) of 19 patients. Regional wall motion abnormalities (RWMA) were localized in distal septum or anterolateral wall in 2 patients with short or long LAD obstruction, respectively.

Recognition of dual LAD is essential to prevent errors of interpretation of the coronary angiogram, to plan optimal strategy for percutaneous coronary intervention or bypass surgery, especially in case of total occlusion, and to understand localized septal or anterolateral RWMA.