Failing to plan is planning to fail. Benjamin Franklin.
The importance of the strategy and good clinical sense
While the cutting-and-sewing part of coronary surgery is important, the real key to a successful outcome is the surgical strategy.
It is important to keep in mind that:
- 1.
Percutaneous coronary interventions have very high periprocedural safety, and the results become inferior to surgery only in the midterm and only if the operative risk for surgery is very low.
- 2.
The traditional coronary artery bypass grafting (CABG) operation [internal thoracic artery (ITA) and veins] is extremely safe and highly reproducible. The available data do not clearly prove a survival advantage with the use of multiple arterial grafts (MAG) and suggest that the difference in favor of the MAG strategy, if existent, is moderate and becomes evident only in the mid- to long-term follow-up.
Due to these considerations, it is my belief that MAG should be used only if the operative risk is not increased by its adoption.
In fact, I do not believe that the available evidence justifies any increase in operative mortality and risk of major complications with adding one or more arterial grafts to the ITA.
The risk/benefit ratio of the use of MAG is dependent not only on patients’ characteristics but also, and critically, on the experience of the operating surgeon and of the operating team .
It is key that the surgeon knows all the available technical solutions, but also that he or she has a realistic idea of his/her own skills and the experience of the team to be able to individualize the operation to the patient, the surgeon, and the setting.
In general, my advice is to err on the side of safety and privilege clinical outcomes over the surgeon’s ego and technique. An alive patient with ITA and veins is a very good result, but a catastrophe after a complex all-arterial bypass operation is not.
The radial artery is more surgeon-friendly and reliable than the right ITA , individual grafts are easier than Y or T grafts, and sequentials have better hemodynamics but require more attention and time. All this is even more evident when operating on the beating heart. Those simple concepts have been the foundation of my grafting strategy in the last two decades.
Indications for the use of arterial grafts
As explained earlier, while the use of MAG should be considered in every patient, the risk/benefit ratio must be carefully evaluated in light of the available evidence and of the operating surgeon’s experience.
It is important to remind that while we have data to suggest improvement in clinical outcomes with the addition of a second arterial graft, there is very little evidence to support a further benefit for three or more arterial grafts or total arterial revascularization, as treatment allocation bias is the likely explanation for the difference seen in the observational series .
I am typically reluctant to use MAG for combined cases and in emergency or unstable situations except in very young patients with excellent cardiac function. If the team is experienced, harvesting of the radial artery does not take longer than harvesting of a saphenous vein and can be considered, although the possible prolonged need for vasopressor may raise concerns of graft spasm. I never use the right ITA in unstable cases.
A classical debate among coronary surgeons is the stenosis cutoff acceptable for arterial grafts. The evidence on the detrimental effect of chronic coronary competitive flow on arterial grafts is relatively solid . The radial and gastroepiploic artery are much less tolerant than the ITA, and the left anterior descending (LAD) territory is much more forgiving than the others (especially the right coronary artery territory).
The impact of preoperative fractional flow reserve (FFR) on arterial bypass graft anastomotic function (IMPAG) trial has shown that an FFR cutoff of 0.78 is associated with 97% anastomotic function of arterial grafts at 6 months . The cutoff is higher (0.81) for side-to-side anastomosis and lower (0.71) for the right coronary artery .
However, most of the patients referred for surgery do not have FFR data, especially for the circumflex and right coronary distribution.
The degree of stenosis is of very limited utility because the same percentage of stenosis may have very different consequences in terms of residual flow based on the diameter of the vessel.
If FFR data are not available, I base my decisions on the ratio between the diameter of the conduit and the diameter of the residual lumen of the target vessel and generally accept a ratio of 1.2 or above. Another important consideration is the graft configuration, as aorta-anastomosed grafts are less affected by competitive flow than in situ and Y grafts.
A classic face-off: right internal thoracic artery or radial artery?
As the left ITA is the cornerstone of CABG, the instinctive second arterial graft for many surgeons is the right ITA.
While the right ITA is a superb conduit (and my first choice for young patients), some points need to be made:
- 1.
The level and amount of the evidence supporting improved patency rate, and clinical outcomes compared to the saphenous vein are by far higher for the radial artery than for the right ITA (the latter is in fact a class I indication in myocardial revascularization guidelines, while the former is a class II ) ( Fig. 2.1 ).
