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.