Best evidence topics (BETs) supporting the use of CB after RA
graft
There are few randomized controlled trials (RCT) and some comparative
studies that investigated the early and chronic role of CB after RA
grafting (Table 1). However, given the high patency rate of the RA
grafts, it is possible that all the published studies were largely
underpowered to detect even moderate differences in outcome.
In Broadman et al. study13, sixty patients underwent
post operative angiography between 1 day and 40 weeks; of these 28 were
on CB. Patency rate of the radial arteries was 95.7% and there was no
association with CB usage.
Acar et al.3 followed up 50 patients. At long-term
follow-up angiography (5-7 years) there were no differences in terms of
graft failure among patients on CB treatment (N=27) versus the one who
had not CB (N=23).
Possati et al14 followed up 90 patients with RA. All
patients received diltiazem for a year postoperatively and 51 patients
stopped the medication during the follow-up. There was no difference in
graft patency between patients who continued or suspended CB. The same
group reported similar results in 200315. Similarly,
Arena et al. did not find differences in terms of graft patency in
patients with or without 6-months CB therapy16.
Shapira et al.17 randomized 161 patients to
postoperative diltiazem or nitrates; key in-hospital and follow-up
clinical end points such as mortality, major morbidity, myocardial
infarction, use of inotropic agents and need for cardiac
catheterization, and reintervention were similar between the two groups.
A 2001 RCT from Gaudino et al.18 assigned 57 and 63
patients to early regimen (1 year) and to chronic regimen CB
respectively. After 5 years, patients were reassessed clinically and by
stress myocardial scintigraphy; 87 of them were re-studied
angiographically. They found no differences regarding either the
clinical and scintigraphic results or the RA angiographic status. They
concluded that after the first post-operative year the continuation of
CB did not affect RA graft patency or clinical and scintigraphic
results.
In 2005, the same author randomized 53 and 47 patients to receive and to
no receive CCB immediately after RA grafting19. At
1-year follow-up all patients were reassessed clinically and
scintigraphically; 83 of them were re-studied angiographically. Again,
no differences in terms of clinical outcome, scintigraphic result and
patency rate was found between groups.
Gaudino et al. in fact questioned the chronic use of CB since they
demonstrated that 1 year after implantation in the coronary artery
circulation, the RA tends to lose the muscular component, becoming
similar to the LIMA20.
Moran et al.21 followed-up 63 and 52 patients after RA
grafting with and without CB respectively. Coronary angiographies were
obtained at 1-year in 50 patients. No differences were observed for
clinical and angiographic end points in the patients that received CB
compared with those who had not.
Cameron et al.22 performed angiogram 5 years post RA
grafting in 50 patients; 37 of these patients received CB. The patency
rate was high (89%) and no correlation with CCB usage was found.
A post-hoc analysis of the Radial Artery Patency
Study23 found that among 440 RA patients, the
incidence of RA spasm was not associated with the compliance with the
prescribed postoperative CB, although compliance with CB use was high
(419 of 440 patients).
Finally, a post-hoc analysis of the Radial Artery Database International
ALliance analyzed24 patient-level database included
732 patients (502 on CCB). At median follow-up of 55 months, CCB therapy
of at least 1 year was found to be associated with significantly lower
risk of MACE and RA graft occlusion.
Nevertheless, despite the lack of definitive evidences, the use of CB
after RA grafting is considered ‘routine’ in many centers. A 2003 survey
of Canadians cardiac units showed that the vast majority of the surgeons
and physicians prescribed CB or other forms of anti-spastic therapy
after RA grafting25.