Congenitally corrected transposition with mirror-image atrial arrangement

Congenitally corrected transposition (discordant atrioventricular and ventriculoarterial connexions) with mirror-image atrial arrangement is much less frequent than the same chamber combinations in the setting of usual atrial arrangement. This scarcity of cases has made their analysis difficult. In this study we have compared the anomalies found in 19 patients with congenitally corrected transposition in mirror-image arrangement with those in 39 patients having usual atrial arrangement. Absolute, relative and attributable risks were calculated for the presence of subvalvar pulmonary stenosis, ventricular septal defect, tricuspid regurgitation, atrioventricular block or the absence of these anomalies for each of the two groups. A greater absolute risk was found for both subvalvar pulmonary stenosis (68.4 vs. 43.6%, respectively) and ventricular septal defect (63.2 vs. 58.9%, respectively). The absolute risk for tricuspid regurgitation was 25.6% in those with usual arrangement as against 21.1% in those with mirror-image arrangement. Atrioventricular block was also more frequent in those with usual arrangement (25.6 vs. 10.5%) as was absence of associated cardiac defects (17.9 vs. 10.5%, respectively). The relative risks were greater for subvalvar pulmonary stenosis and ventricular septal defect in the patients with mirror-image as opposed to usual atrial arrangement (1.57: 1.00 and 1.07: 1.00, respectively), contrasting with greater relative risk for tricuspid regurgitation (1.26: 1.00), atrioventricular block (2.43: 1.00) and absence of associated anomalies (1.70: 1.00) in the patients with usual arrangement. The attributable risk for subvalvar pulmonary stenosis was estimated to be 24.8% and ventricular septal defect 4.3% for those having mirror-image atrial arrangement.(ABSTRACT TRUNCATED AT 250 WORDS)