Assessment of Heart Failure Signs and Symptoms in DMD
HF management has been well study with guidelines from multiple medical associations supporting the use of these guidelines57-59. HF warning signs and symptoms are common and direct care and frequently used as outcomes measures in trials. These include shortness of breath, persistent cough or wheezing, building up of fluid in the tissue (edema), fatigue, lack of appetite, nausea, confusion or impaired thinking as well increase heart rate. The utility of HF classifications including the NYHA classification have been well published and shown to improve patient outcomes 58, 60. Stages of HF established the extent of risk and disease and are used to guide treatment changes clinically and used to determine outcomes in therapeutic trials61-63. Neuromuscular disease (NMD) such as DMD universally develop cardiomyopathy and HF19. Due to skeletal and respiratory muscle disease, HF signs and symptoms are frequently masked and have limited utility. DMD-CM patients lack traditional HF symptoms making NYHA classification challenging even in advances stages64, 65. Care guidelines frequently comment on HF in DMD-CM but suggest lack of symptoms due to skeletal muscle weakness and the use of supportive equipment. Many concluded that HF signs and symptoms are frequently absent and when present are vague and non-specific 66, 67. In the absence of reported symptoms, HF scoring systems, such as the NYHA functional classification, are often falsely reassuring, even in the setting of marked ventricular dysfunction. In a study by the Pediatric Cardiomyopathy Registry Study Group only 30% DMD patients have any HF symptoms at diagnosis but the group was not able to determine if these symptoms were all cardiac or from skeletal muscle weakness. The team concluded that DMD patients have a higher mortality than non-DMD cardiomyopathy patients and recommended imaging rather relying on HF symptoms to track and manage DMD patients68.