Results
Since the turn of the 21st century, patients undergoing the arterial switch operation have been reported with perioperative mortalities ranging between nil and 6%.19,48,49 In the data analysed by NICOR, for example, which collates overall results for all centers in the United Kingdom, 118 procedures were reported for 2019 through 2020, with 4 deaths within 30 days of the procedure.50 Some patterns, such as the intramural variants, or those with single sinus origin, continue to be associated with a significantly increased risk of death, which persists over time.19-55 Even with the commonest types of coronary arterial anatomy, transfer is not always straight forward. In Melbourne, for example, where results have been excellent in terms of mortality and overall outcomes, some manipulation of the coronary arteries subsequent to transfer was required in one-fifth of cases.33 It has emerged, nonetheless, that certain patterns are likely to create problems. Most worrying is the intramural arrangement. Individuals with these patterns continue to suffer increased mortality, reported by some at 28%, compared to 3% in those with usual patterns in the same hands. These individuals also suffer an increased incidence of overall lethal and non-lethal coronary events, at 41% as opposed to 4.7% for the remaining patterns.26-28,48,51-55 The risk for single sinus origin has decreased in institutions dealing with large volumes, such as Marie-Lannelongue Hospital in Paris.12 These investigators established the risk factors for coronary arterial events in a large cohort,12,26,53,56 noting 7.2% incidence of events in those individuals with single sinus origin. Complex patterns were associated with a 6.5 fold increased risk of death.53,54 Others have also reported problems with loooing arteries in the setting of single sinus origin, noting significant mortality (OR 2.9, 95% CI: 1.3-6.8). It was the intramural arrangement, nonetheless, that still induced the greatest mortality (OR 6.5, 95% CI: 2.9-14.2). Overall, patients with any coronary pattern other than the usual one had nearly twice the mortality.26
Better indications can be found on the basis of meta-analysis. In one large analysis,26 results were combined from 9 independent case series, providing details of almost 2,000 patients.12,13,25,26,54,56-59 Most studies had used the Leiden classification. Complex arterial patterns were again associated with a 6.5 fold increased risk of death. Another meta-analysis of results from 20 institutions also showed single sinus origin and the intramural variants to be associated with problems, in this instance postoperative myocardial ischemia.60Results, perhaps not surprisingly, however, vary markedly in difference centers. Metton and associates, for example, described their experience with 46 patients having the intramural arrangement from an overall cohort 919 patients.51 They reported 11 deaths prior to discharge from hospital, with 2 additional deaths at 51 and 105 days, giving overall mortality of 28%.51 In three other series, mortalities have been reported at 14% and 5%.49,55 The Melbourne group, nonetheless, repaired 28 individuals having the intramural pattern, with no deaths.48 Thus, even the intramural variant is not necessarily a risk factor in experienced hands.