4 | DISCUSSION
To the best of our acknowledgement, this is the first study that
compares different definitions of CR in the same patient, abolishing all
confounding variables of multi-person analysis. In this series, a
complete functional revascularization (all viable myocardial territories
are reperfused) was the only definition with increased long-term
survival after coronary surgery. According to recent studies, CR based
on the functional definition is the preferred strategy for PCI [1].
However, the role of functional revascularization for CABG is not so
obvious [12-14]. For example, the substudy of the STITCH TRIAL
failed to prove that a functional revascularization was associated with
a greater likelihood of survival in ischemic left ventricular
dysfunction, when adjusted for patients’ baseline variables [12].
Toth et al [13] did not find a significant difference of
adverse cardiovascular events at 3 years between patients with
fractional flow reserve-guided CABG and angiography-guided CABG.
In literature, there are many different definitions of CR [11].
Probably the most used definition is the anatomical conditional
revascularization, where all epicardial vessels with a diameter
exceeding ≥1.5 mm and a luminal reduction of ≥50% in at least one
angiographic view are revascularized. Recent studies supported by this
definition have reported conflicting results. An example is two
different post hoc analysis of the SYNTAX trial data, with one
study concluding that incomplete surgical revascularization did not
impact outcomes, while the other study found relation between incomplete
revascularization and adverse outcomes [4,5]. In this study, an
incomplete anatomical conditional revascularization was not associated
with an increased follow-up mortality.
Complete anatomical unconditional revascularization (all stenotic
vessels are revascularized, irrespective of size and territory supplied)
is very difficult to achieve as seen in our study with only 13% of the
patients. Most common reasons are calcified/diffusely diseased small
vessels, difficult exposure, hemodynamic instability, porcelain aorta
and limited conduits. Furthermore, this definition has not beeing
associated with increased survival in literature [8]. Our research
reached the same conclusion. From a survival perspective, the added
effort to bypass all branch vessels may not be necessary.
This series validated that numerical revascularization - number of
stenotic vessels equals to the number of distal anastomoses - is not
relevant in clinical practice.
Our study also verified that age and cardiac dysfunction are independent
predictors of late mortality, as seen in earlier studies [3].
There are limited data regarding the relation between CR and
perioperative outcomes. Lee et al found a relation between
incomplete revascularization and MACCE in patients with left ventricular
dysfunction [10]. In this research, the definition of complete
revascularization did not have an impact on MACCE, possibly indicating
the impact of complete revascularization appears to be maximal in the
long term.
The need to repeat revascularization was not associated with any
definition of CR. A low number of events can explain this result.
This study has multiple limitations. It is based on the retrospective
analysis of a population determined by having or not a myocardial
perfusion scintigraphy prior to CABG. For that reason, it is a small
sample size with low number of events. Surgery was carried by different
surgeons and the revascularization was dependent on their clinical
assessment. It was not possible to evaluate the reasons for incomplete
revascularization. The constrained access to other institutions’ records
limited us to accurately identify morbidity during follow-up.