TTR and hydrops fetalis: A likely explanation for this trend is that initially patients who were referred for evaluation were those who had been preselected to have positive biopsy evidence or DNA evidence of ATTR,[4] but following the issuance of a series of imaging guidelines by professional societies, referring physicians cast a wider net due to the realization that ATTR as a cause of HF had been under-recognized.[16] Current guidelines suggest that patients be evaluated for possible amyloidosis who have unexplained HF and increased left ventricular wall thickness.