Clinical Usefulness of Echocardiographic Measurement of Proximal Aortic Diameter in Early Differentiation Between Type A Acute Aortic Dissection and ST-Segment-Elevation Myocardial Infarction.

Background Contradictions between management modalities of type A acute aortic dissection (TAAAD) and ST-elevation-myocardial infarction (STEMI) may result in clinical catastrophe. Therefore, we aimed to explore which 2-dimensional echocardiography (2DE) findings are optimal for differentiating TAAAD from STEMI. Methods and Results This study included 340 patients with STEMI and 340 patients with TAAAD who underwent 2DE in the emergency department between 2012 and 2021. The proximal ascending aorta (PAA) diameter and other echocardiographic parameters were analyzed. PAA diameters were measured at 4 levels in the parasternal view: Valsalva, the sinotubular junction (STJ), the PAA at 1 cm above the STJ, and the PAA at 2 cm above the STJ. Receiver-operating characteristic curve analysis showed that Valsalva, STJ, PAA at 1 cm above the STJ, and PAA at 2 cm above the STJ were significant predictors of TAAAD (areas under the curve: 0.777, 0.924, 0.965, and 0.975, respectively; P <0.001) with the respective cutoff values of 39.4, 38.5, 39.8, and 41.2 mm. Multivariable analysis suggested that all 2DE parameters were significant predictors of TAAAD. Among the 2DE parameters examined, the incorporation of PAA at 2 cm above the STJ to clinical indicators exhibited the most significant diagnostic capability (C-statistics, 0.97; net reclassification improvement, 1.81; integrated discrimination improvement, 0.61). When only TAAAD with coronary malperfusion and STEMI were analyzed, the diagnostic utility of PAA at 1 cm above the STJ was evident (C-statistics, 0.99; net reclassification improvement, 1.79; integrated discrimination improvement, 0.67), with PAA at 2 cm above the STJ ranking second in diagnostic significance (C-statistics, 0.99; net reclassification improvement, 1.12; integrated discrimination improvement, 0.66). Conclusions PAA measurements were the most beneficial for diagnosing TAAAD in all 2DE findings and TAAAD from STEMI.