Frequency and significance of left coronary arterial dominance in isolated aortic stenosis

Myocardial infarction during aortic valve replacement has previously been reported to result from obstruction of a branch of the left main coronary artery by the perfusion cannula. Patients with a dominant left coronary arterial system may be at greater risk. To assess the frequency and significance of a dominant left coronary arterial system the coronary angiograms of 75 consecutive patients more than 34 years of age with isolated aortic stenosis were studied and compared with those of a control group of 150 patients. Among the patients with aortic stenosis, 19 (25 percent) had left dominance, 9 (12 percent) a balanced circulation and 47 (63 percent) a dominant right coronary arterial system. Among control patients, 14 (9 percent) had left dominance 18 (12 percent) a balanced system and 118 (79 percent) right dominance. The increased prevalence of left dominance in patients with aortic stenosis was significant (P less than 0.005). Among patients with aortic stenosis, the left main coronary artery was shorter (P less than 0.01) in those with left dominance (6.2 +/- 1.3 mm [mean +/- standard error]) than in those with right dominance (9.9 +/- 0.7). Sixty-nine patients with aortic stenosis underwent aortic valve replacement. Perioperative myocardial infarction occurred in 4 of 15 (26.7 percent) of those with left dominance and in 4 of 54 (7.4 percent) of those with right dominance or a balanced circulation (P less than 0.05). Perioperative myocardial infarction occurred in all three patients with left dominance and obstructive coronary artery disease. The increased prevalence of a dominant left coronary arterial system in aortic stenosis suggests that this may be part of a developmental complex. Patients with left dominance have a shorter left main coronary artery than patients with right dominance. They also have an increased risk of perioperative myocardial infarction if there is associated obstructive coronary artery disease. Preoperative information about the coronary arterial anatomy and extent of coronary artery disease may be helpful in planning the use of coronary perfusion and other myocardial preservation techniques during surgery in order to reduce the incidence of myocardial infarction.