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Page 10 of 16 Harik et al. Vessel Plus 2023;7:30 https://dx.doi.org/10.20517/2574-1209.2023.124

[76]
discontinuing CCBs after the first postoperative year and one examining the effect of no CCB in the early
[77]
postoperative period , found no difference in angiographic or clinical outcomes at one-year and five-year
follow-up, respectively. A post-hoc analysis including 440 CABG patients receiving the RA from the Radial
Artery Patency Study (RAPS) found that compliance with postoperative CCV regimen did not affect the
incidence of the highest degree of RA graft spasm, demonstrated by string sign . However, in a post-hoc
[78]
analysis of 732 patients from the RADIAL database, CCB therapy was associated with a significantly lower
risk of major adverse cardiac events (HR: 0.52, 95%CI: 0.31-0.89, P = 0.02) and RA graft occlusion (HR: 0.20,
95%CI: 0.08-0.49, P < 0.001) . In addition, if antispasm therapy is used, the choice of the best CCB is
[79]
unclear. The aforementioned RADIAL analysis reported that compared with no CCB, amlodipine
(HR: 0.30; 95%CI: 0.12-0.74, P = 0.009) and diltiazem (HR: 0.20; 95%CI: 0.07-0.51, P < 0.001) were associated
[79]
with a similar protective effect on the risk of RA graft occlusion . The use of antispasm therapy after
CABG with RA grafting therefore requires further investigation.

CONSIDERATIONS FOR USE OF THE RITA
Graft configuration
The RITA can be used as a free graft from the aorta or as an in-situ graft. A longitudinal single-center study
of over 1,331 CABG patients found that the patency of the in-situ RITA was 91% and the patency of the free
[80]
RITA from the aorta was also 91% at 15-year follow-up . In an RCT of 304 CABG patients receiving BITA
grafting (147 in-situ, 152 Y-graft), there was no difference in RITA anastomotic patency by configuration at
six-month follow-up (97.0% vs. 96.0%, P = 0.69) , and no difference between groups in major adverse
[81]
cerebral and cardiovascular events, defined as mortality, need for reoperation, ICU length of stay, and all
cardiovascular morbidity (P > 0.05 for all). At the mean 3.5-year angiographic follow-up, there was no
difference between the in-situ RITA (93%) and Y-graft (96.5%; P = 0.10) patency. However, at a mean seven-
year follow-up, the in-situ RITA had a higher incidence of major adverse cerebral and cardiovascular events
(34% vs. 25%) . An additional consideration for the use of the in-situ RITA is the manner in which it is
[82]
directed to the target vessels: if it crosses the midline anteriorly, there is an increased risk of injury during
sternal reentry at reoperation. Directing the RITA via the transverse sinus may limit the target vessels of the
RITA (i.e., it may only reach and revascularize the left circumflex branches).

Target vessels
While the RITA has well-documented poorer patency than the LITA, the target coronary vessel may
influence RITA patency. The aforementioned longitudinal single-center study of 1,331 patients with
bilateral ITA grafting and 15-year imaging follow-up found that there was no difference between patency of
the RITA and the LITA in instances when the RITA was grafted to the LAD (94.4% vs. 95.4%; P = 0.50);
however, the patency of the RITA was significantly lower when grafted to non-LAD coronary targets
[80]
(P < 0.001) . This study also found that RITA grafts anastomosed to target coronary arteries with < 60%
stenosis had lower patency rates, while those anastomosed to target coronary arteries with > 80% stenosis
had higher patency rates, showing again that the degree of target vessel stenosis affects arterial graft patency.

ON-AND OFF-PUMP CABG AND GRAFT PATENCY
While the majority of CABG surgeries in the United States and Europe are performed with the use of
cardiopulmonary bypass, off-pump CABG is an alternative approach that may avoid the negative effects of
[83]
cardiopulmonary bypass on the patient . The results of randomized trials of on- vs. off-pump CABG with
angiographic follow-up have been mixed [84-87] . The Randomized On/Off Bypass (ROOBY) trial included
2,203 patients randomized to on- or off-pump CABG and at one-year follow-up found a higher patency rate
[86]
in arterial (91.4% vs. 85.8%; P = 0.003) and vein (80.4% vs. 72.7%; P < 0.001) grafts . However, the CABG
Off or On Pump Revascularization Study (CORONARY) included 4,752 patients randomized to on- or off-