Based on the previously mentioned AVB severity and LV change, AVBpatients with unknown etiologies were divided into four types with distinctivecharacteristics, of which 17% showed risk features such as advanced AVB,increased LVEDD, and high NT-proBNP levels [35, 36] and were classified as thesevere phenotype. The gene discussed is NPPB; the disease is atrioventricular block.