 [ Symptoms ] low resting heart rate can it be a secondary adrenal insufficiency if not what is cause [ Disease ] hi as you stated it was just after a traumatic event so the is mostly stress however to be safe do a thyroid profile to check for hypothyroidism as parasympathetic system start working few days after the traumatic event adrenaline drops normaly this is called parasympathetic overdrive if your heart rate does not improve on its own on daily bases you will have to consult both a psychiatrist and cardiologist good luck