▁have ▁an ▁increased ▁risk ▁of ▁developing ▁ab normal ▁heart ▁rh yth ms . ▁These ▁ab normal ▁heart ▁rh yth ms ▁often ▁occur ▁at ▁a ▁young ▁age . ▁ ▁They ▁may ▁take ▁relatively ▁ben ign ▁forms ▁such ▁as ▁at rial ▁f ibr ill ation , ▁leading ▁to ▁sympt oms ▁of ▁pal pit ations , ▁breath less ness , ▁or ▁fat igue . ▁According ly , ▁at rial ▁f ibr ill ation ▁present ing ▁in ▁a ▁new born ▁should ▁raise ▁the ▁susp icion ▁of ▁short ▁Q T ▁synd rome . ▁In ▁addition , ▁far ▁more ▁dangerous ▁heart ▁rh ythm ▁dist urban ces ▁such ▁as ▁vent ric ular ▁f ibr ill ation ▁can ▁also ▁occur ▁in ▁those ▁with ▁short ▁Q T ▁synd rome , ▁leading ▁to ▁black outs ▁or ▁even ▁sudden ▁death . ▁ ▁More ▁than ▁a ▁third ▁of ▁those ▁with ▁short ▁Q T ▁present ▁with ▁vent ric ular ▁arr h yth mi as ▁or ▁sudden ▁card iac ▁death , ▁while ▁one ▁in ▁five ▁cases ▁are ▁detected ▁during ▁family ▁screen ing , ▁and ▁one ▁in ▁five ▁cases ▁are ▁found ▁incident ally ▁after ▁an ▁electro card i ogram ▁( E CG ) ▁has ▁been ▁recorded ▁for ▁another ▁reason . ▁ ▁If ▁someone ▁with ▁short ▁Q T ▁synd rome ▁is ▁exam ined ▁while ▁their ▁heart ▁is ▁be ating ▁in ▁an ▁ab normal ▁rh ythm ▁such ▁as ▁at rial ▁f ibr ill ation , ▁this ▁can ▁be ▁detected ▁by ▁feeling ▁their ▁pul se . ▁ ▁No ▁ab normal ▁signs ▁will ▁usually ▁be ▁found ▁when ▁exam ining ▁someone ▁with ▁short