Researchers in USA and Australia have found a new potentially treatable cause of sudden infant death, consisting of idiopathic ventricular fibrillation preceded by ST segment changes and QRS widening. This first report was published online in June in Circulation Arrhythmia and Electrophysiology.
Infants with structurally normal hearts who have ventricular arrhythmia-related sudden cardiac arrest are uncommon. Christina Y Miyake (Department of Pediatrics, Lucile Packard Children’s Hospital, Stanford University, Palo Alto, USA) and others wrote: “There have been no previously published reports of infants less than three months of age with ventricular fibrillation in which a primary diagnosis could not be determined.”
In this retrospective review, Miyake et al analysed three unrelated infants, each newborn less than two months old, with structurally normal hearts and normal myocardial function, who survived multiple episodes of polymorphic ventricular tachycardia and ventricular fibrillation arrests preceded by unique ECG changes.
According to Miyake et al, the three infants (a five-week old Southeast Asian female, a two-week old Hispanic female and a five-week old Caucasian male) presented with ST changes and QRS widening 2–5 minutes before ventricular fibrillation followed by premature ventricular contractions or polymorphic ventricular tachycardia (PMVT) 30 seconds to one minute before ventricular fibrillation. There was complete resolution of ST segments and QRS widening within minutes after successful defibrillation with recurrence of ST and QRS changes prior to each ventricular fibrillation episode. Miyake et al wrote: “These prodromal ECG changes have not been previously described. We believe that clinical recognition of this new syndrome with newly described, stereotypical ECG changes preceding ventricular arrhythmia may define a new cause of sudden infant death that has not been previously known.”
“Despite through evaluation, we have been unable to determine a diagnosis in any of the three infants,” said Miyake et al. All three infants showed benign family history, their resting ECGs were normal with no evidence of long or short QT syndrome, Brugada syndrome, early repolarisation or J wave syndromes. The researchers also noted that none of the infants were ill and infectious work-up was negative. “Our interim diagnosis, therefore, is idiopathic ventricular fibrillation, an entity that has been described in adults but not in infants. The mode of onset of ventricular fibrillation seen in each of these infants has never been described in the adult,” the authors wrote.
Regarding to treatment, amiodarone, sedation, sodium channel blocking agents and/or ventricular pacing were effective in suppressing acute events. After treatment, the authors reported, the three infants had no further arrhythmias and are still alive. More genetic testing is needed and “may uncover the genetic basis for this potentially new infant arrhythmic sudden death syndrome,” said Miyake et al.
They concluded: “These findings may represent a new potentially treatable cause of sudden infant death. Recognition of these prodronal changes may be important in future management and survival of these infants.”