Right ventricular echocardiographic parameters for prediction of proximal right coronary artery lesion in patients with inferior wall myocardial infarction

BACKGROUND: Classifying the location of an occlusion in the culprit artery during ST-elevation myocardial infarction is important for risk stratification to optimize treatment. OBJECTIVES: To compare the validity of echocardiographic parameters assessing right ventricular (RV) function for the prediction of proximal right coronary artery (RCA) lesion in patients with inferior wall myocardial infarction. METHODS: The study included 76 patients after their first episode of acute inferior myocardial infarction with significant RCA lesion (43 patients with proximal RCA stenosis and 33 patients with distal RCA stenosis). Full echocardiographic examination was done before revascularization, including RV dimension, tricuspid annular plane systolic excursion, and tissue Doppler imaging of RV free wall at the level of the tricuspid annulus and recording the following variables: peak systolic velocity (Sm), peak early diastolic velocity, peak late diastolic velocity, ejection time (ET), isovolumetric relaxation time (IVRT), isovolumetric contraction time (IVCT), and myocardial performance index (MPI), which was calculated as (MPI = IVRT + IVCT/ET). RESULTS: Patients with proximal RCA showed significantly lower Sm (10.44 ± 2.61 cm/s vs. 12.11 ± 2.94 cm/s, p = 0.013) and shorter ET (224.18 ± 49.96 ms vs. 280.90 ± 46.12 ms, p = 0.001). While IVRT, IVCT, and MPI were significantly higher (95.25 ± 19.22 ms vs. 68.48 ± 12.77 ms, p = 0.001; 81.62 ± 23.59 ms vs. 60.90 ± 17.38 ms, p = 0.001; and 0.82 ± 0.222 vs. 0.47 ± 0.10, p = 0.001, respectively) when compared with patients with distal RCA stenosis. Multiple regression analysis including (tricuspid annular plane systolic excursion, Sm, and MPI) showed that the most independent predictors for proximal RCA lesions were MPI (p = 0.0001). The receiver operator characteristic curve for MPI showed areas under the curve of 97% and a confidence interval of 93%. A cut-off value of 0.58 for MPI had a sensitivity of 95% and specificity of 97% for the diagnosis proximal RCA. CONCLUSIONS: The most independent predictors for proximal RCA lesion is MPI.