ECHOCARDIOGRAPHIC DIFFERENTIATION BETWEEN ANOMALOUS LEFT CORONARY ARTERY FROM THE PULMONARY TRUNK AND DILATED CARDIOMYOPATHY

Direct visualization of an anomalous left coronary artery from the pulmonary trunk (ALCA) is not always possible by cross-sectional echocardiography (CSE). By contrast, a large right coronary artery (RCA) in ALCA can usually be seen. We reviewed the diagnostic value of the RCA diameter measurement by CSE in the differentiation between ALCA and dilated cardiomyopathy (DCM) of other etiology. In 28 controls, RCA increased with age; RCA(mm) = 0.781 log(months) + 0.639 (r=0.829, SEE=0.306), but RCA/aortic root ratio (RCA/AO) showed no variation with age (11.9±2.0%). Morphometric criteria for ALCA was made as RCA larger than the 95% confidence limit of normal or RCA/AO larger than 17%. Diagnostic criteria of (1) direct visualization of ALCA, (2) diastolic flow in pulmonary artery by Doppler echocardiography and (3) RCA morphometry were assessed in 10 patients with ALCA (3-105 mos; median 8.5 mos) and 11 with DCM (2-113 mos; median 7 mos) by blind observers. RESULT: There were no false positive diagnoses of ALCA. Sensitivity was 40% by (1); 40% by (2); 70% by (3); 60% by (1+2); and 80% by (1+3). Interobserver agreement was assessed in 18 patients and was significantly concordant: r=0.934 for RCA and r=0.905 for RCA/AO. CONCLUSION: Careful visualization and measurement of RCA can accurately confirm a diagnosis of ALCA.