The authors have shown that 15–20% of affected fetuses develop more diffuse myocardial disease before birth and others may have myocardial dysfunction after birth even with adequate pacemaker therapy. Isolated EFE and cardiomyopathy may be seen in NLE without conduction abnormalities. In some babies born to mothers with lupus autoantibodies, EFE is diagnosed prenatally, whereas in others it is diagnosed several years after birth. Development of late onset cardiomyopathy or EFE may be due to the progression of the perinatal impairment of myocardium, which requires a secondary trigger such as viral infection or genetic predisposition, or may be induced by pacing or metabolic disorders