Comparison of alternate preparative techniques on wall thickness in
coronary artery bypass grafts: the HArVeST randomised controlled trial
Abstract
Background: The success of coronary artery bypass grafting surgery
(CABG) is dependent on long-term graft patency, which is negatively
related to early wall thickening. Avoiding high-pressure distension
testing for leaks and preserving the surrounding pedicle of fat and
adventitia during vein harvesting may reduce wall thickening. Methods: A
single-centre, factorial randomised controlled trial was carried out to
compare the impact of testing for leaks under high versus low pressure
and harvesting the vein with versus without the pedicle in patients
undergoing CABG. The primary outcomes were graft wall thickness, as
indicator of medial-intimal hyperplasia, and lumen diameter assessed
using intravascular ultrasound after 12 months. Results: 96 eligible
participants were recruited. With conventional harvest, low-pressure
testing tended to yield a thinner vessel wall compared to high-pressure
(mean difference MD (low minus high) -0.059mm, 95%CI -0.12, +0.0039,
p=0.066). With high pressure testing, veins harvested with the pedicle
fat tended to have a thinner vessel wall than those harvested
conventionally (MD (pedicle minus conventional) -0.057mm, 95%CI -0.12,
+0.0037, p=0.066, test for interaction p=0.07). Lumen diameter was
similar across groups (harvest comparison p=0.81; pressure comparison
p=0.24). Low pressure testing was associated with fewer hospital
admissions in the 12 months following surgery (p=0.0008). Harvesting the
vein with the pedicle fat was associated with more complications during
the index admission (p=0.0041). Conclusions: Conventional saphenous vein
graft preparation with low pressure distension and harvesting the vein
with a surrounding pedicle yielded similar graft wall thickness after 12
months, but low pressure was associated with fewer adverse events.