Asystoles during infancy recorded by home memory monitors. Benign events?

To assess the frequency and clinical significance of asystole (sinus arrest > or = 2.0 seconds) and the incidence of bradycardia in infants prescribed home cardiorespiratory monitors and to test the hypothesis that asystoles are more likely to occur in preterm infants.

Prospective, consecutive sample of monitor printouts.

All 291 printouts from the memory monitors of 161 patients received during a 2-month period were analyzed.

University hospital providing primary and referral care.

Asystoles and bradycardias; clinical course of patients with asystoles.

Eight patients (5.0%) had 32 episodes of asystole lasting 2.0 to 4.3 seconds (group 1). Fifty-three patients (32.9%) had true bradycardia alarms but no asystoles (group 2). One hundred patients (62.1%) had neither asystoles nor bradycardias (group 3). Preterm infants constituted 88% of group 1 and 81% of group 2 but only 58% of group 3. Infants were more likely to be full-term in group 3 than in the other 2 groups (chi 2, P = .02). Birth weights were lower in group 1 than in group 3 (P < .05, 1-tailed t test). There were 479 true bradycardias; 72.2% lasted 10 seconds or less, 26.3% were longer than 10 seconds but no more than 20 seconds, and 1.5% were longer than 20 seconds. None of the 8 patients with asystoles required resuscitation for their asystoles; all survived and were free of any life-threatening events after their monitors were discontinued and up until their first birthday.

Asystoles occur more commonly in preterm infants; those pauses in the 2.0- to 4.0-second range seem to be benign. Studies of long-term recordings are needed to redefine asystole in both normal preterm and fullterm infants. These data would help further refine current guidelines for pacemaker implantation during infancy.