Identification of infants destined to die unexpectedly during infancy: evaluation of predictive importance of prolonged apnoea and disorders of cardiac rhythm or conduction.

Twenty four hour tape recordings of electrocardiogram and breathing movement were made prospectively in 6914 full term and 2337 preterm infants or infants of low birth weight during their first six weeks of life. These recordings included 40 obtained in 29 infants who subsequently suffered the sudden infant death syndrome and 13 obtained in 10 other infants who died suddenly and unexpectedly. None of the recordings obtained in the infants who suffered the sudden infant death syndrome showed prolonged apnoea (cessation of breathing movement for 20 seconds or more) or pre-excitation. One infant had multiple ventricular premature beats (38/hour). Compared with recordings obtained in 211 control infants who did not die none of the recordings obtained in the infants who suffered the syndrome showed abnormal prolongation of the QT interval.