Does the prophylactic and therapeutic use of beta-blockers in preoperative patients with tetralogy of Fallot significantly prevent and treat the occurrence of cyanotic spells?

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was 'Does the use of beta-blockers significantly prevent and treat the occurrence of cyanotic spells in preoperative infants with tetralogy of Fallot?' Altogether, 80 papers were found using the reported search, of which 6 represented the best evidence to answer the clinical question. The author, journal, date, country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. The participants in the papers reviewed were uncorrected (native or palliated) tetralogy of Fallot patients, all younger than 18 years of age, with some patients younger than 1 year. Each study reviewed included at least 10 patients, and all the studies were case series. Although even the most recent studies found were from 30 years ago, their data remain relevant. Several reviews reported either cases of overdosage or changes in efficacy of treatment after long-term usage. Four of the 6 case reviews demonstrated a decrease in the number of recurring cyanotic spells in at least 66% of the participants, following the introduction of beta-blockers. We can therefore conclude that the use of beta-blockers prevents the occurrence of cyanotic spells in preoperative patients with tetralogy of Fallot. There were insufficient data to establish optimum dosages or duration of treatment.