STUDY LIMITATIONS
Our study has several limitations to be acknowledged. Our data was
derived from a retrospective review in a single institution. A
multi-center approach, incorporating a larger sample size, would be more
adequately powered to analyze more subtle differences between outcomes.
Our patients were not randomized to a given revascularization strategy.
Although the impact of this may be somewhat mitigated by the fact that
the treatment for each patient was not selected by a single
practitioner, but rather by a multidisciplinary heart team, the fact
that the overwhelming majority of patients with TVD in our institution
were treated by either CABG or multi-vessel PCI reflects an intrinsic
selection bias for those individuals offered HCR.
Due to the differences in SYNTAX scores between patient groups, our data
cannot be used to comment on the superiority of one revascularization
strategy over another. The data does, however, afford us the opportunity
to evaluate the effectiveness of a ‘real-world’ heart team approach to
the management of patients with TVD. Residual SYNTAX score calculations
in our CABG and PCI-first HCR patients assumed patency of all surgical
bypass grafts; although suboptimal, it was not deemed appropriate to
undertake formal angiography in asymptomatic patients for the sole
purpose of calculating a residual SYNTAX score.
We were able to achieve 100% follow up for our primary end-point,
namely, all-cause death at 8 years. We utilized the National Death Index
as our primary source for 8-year survival data; though this methodology
may somewhat underestimate true mortality (30). Patients that underwent
multi-vessel PCI had a numerically higher amount of death than CABG or
HCR, however this did not meet significance. We cannot exclude the
possibility of a type II error, as our study size was limited. With
respect to the other long-term outcomes that were reported, it is
important to note that there were 15 patients in the CABG arm, 5 in the
PCI group, and 3 in the HCR cohort, that were all lost to follow-up.
Furthermore, we are unable to correct for the use of DAPT which may
confound the long-term results of MACE.
Our institution has extensive experience with minimal-access,
robotic-assisted LIMA to LAD grafting, as well as with complex PCI. Our
results may, therefore, not be directly generalizable to other
institutions who have less experience with either revascularization
strategy. Similarly, the low perioperative stroke rate observed in our
sternotomy CABG cohort may not necessarily be translatable to other
patient populations, given that we perform the majority of these cases
‘off-pump,’ a practice pattern not currently adopted by most surgical
centers in the United States (31). Despite our center’s surgical
experience, only 100 patients were treated with HCR, which reflects our
selectiveness of the revascularization strategy.