Secondary clinical outcomes include left ventricular ejection fraction, peak global longitudinal strain measured by echocardiography, N-terminal prohormone of brain natriuretic peptide (NT-proBNP), New York Heart Association (NYHA) functional class, Kansas City Cardiomyopathy Questionnaire (KCCQ) quality of life score, and clinical outcomes (all-cause mortality, HF hospitalizations, and HF emergency room visits). The gene discussed is NPPB; the disease is hydrops fetalis.