Frequency and Predictors of Internal Mammary Artery Graft Failure and Subsequent Clinical Outcomes: Insights From the PREVENT IV Trial
PREVENT IV trial participants who had undergone either a RIMA or LIMA to LAD anastomosis and underwent an angiogram at 1 to 1.5 years (n=1539) were analyzed for mammary graft failure (defined as >75% stenosis). Mammary graft failure occurred in 8.6% of patients, and independent predictors of graft failure were an LAD stenosis < 75% and the presence of a graft to the diagonal. These associations suggest competitive flow may play an important role in mammary graft failure and raise the question of whether LAD stenoses < 75% without evidence of ischemia should be bypassed and whether diagonal grafts should be more selectively performed.
I think that the definition of ITA disuse imputable to the so called comoetitive flow should be very precise.
There are many physiological factors to be taken in consideration explaining distal ITA restriction phenomena :
1) the site of distal anastomosis in respect to the origine of septal branches:
The powerfull systolic backflow (more pressurized than intra-ITA systolic pressure) may be a source of baro-trauma to ITA, especially when the distal anastomosis is place more proximally and in face of a septal branch origine
2) ITA diameter:
Although ITA is prone to adapt to flow, however, increased flow (therefore increased velocity) may lead to ITA diameter reduction up to functionnal collapse that is known as supra-maximal flow. Therefore, the critical ITA diameter to be used for sequential anastomosis should be further established.
In a sequential anastomosis, the smallest distal diameter of ITA is assigned to LAD where higher flow demand is required.
A smart solution will be to use ITA as a mini reverse-T composite graft where the free ITA segment (inter-coronary bridge) can be reveted as to provide ITA with greater arterial graft diameter.
This study may indirectly highlight the need of pre operative mapping (CT angiography and FFR) for more precisely performing coronary revascularisation surgery in one hand, and develloping revascularisation techniques fixing competitive flow such as Coronaro-Coronary grafting approches on the other hand.
Cordially
Erratum:
Provide LAD instead provide ITA