Anatomy of the left main coronary artery of particular relevance to ablation of left atrial and outflow tract arrhythmias

Abstract

Left main coronary artery (LMCA) damage is a rare but catastrophic complication of cardiac ablation procedures. The purpose of this study was to describe the anatomic relationships of the LMCA to its adjacent structures using analysis of computed tomographic coronary angiograms (CTCA). We studied 100 patients (55 males, age 51 ± 10 years) who were investigated for chest pain with CTCA. The relationships between the LMCA and adjacent structures were described by analysis of 2-dimensional images and 3-dimensional reconstructions. The LMCA coursed within 5 mm of the anterior left atrial endocardium and/or base of left atrial appendage in 49% (within 2 mm in 17%) and from the pulmonary artery in 90% (within 2 mm in 43%). The LMCA was within 5 mm of the right ventricular outflow tract in 1%. In 4% the LMCA coursed inferiorly, remaining within 5 mm of the left aortic sinus of Valsalva at a vertical distance >5 mm from the inferior margin of the LMCA ostium. The LMCA is often intimately related to the anterior left atrium, left atrial appendage base, and pulmonary artery and occasionally to the inferior part of the left aortic sinus of Valsalva and thus is exposed to the risk of injury during ablation in these areas. The LMCA is rarely close to the right ventricular outflow tract.