The effect of adding ticagrelor to standard aspirin on saphenous vein graft patency in patients undergoing coronary artery bypass grafting
Selected in Circulation by G. Bonnet , A. N. Calik
POPular CABG: A randomized, double-blind, placebo-controlled trial to evaluate the efficacy and safety of ticagrelor on SVG patency when added to low-dose aspirin in post-CABG patients.
References
Authors
LM Willemsen, PWA Janssen, J Peper, MA Soliman-Hamad, AHM van Straten, P Klein, CM Hackeng, U Sonker, MWA Bekker, C von Birgelen, MA Brouwer, P van der Harst, EA Vlot, VHM Deneer, DRPP Chan Pin Yin, ME Gimbel, KF Beukema, EJ Daeter, JC Kelder, JGP Tijssen, BJWM Rensing, HW van Es, MJ Swaans, and JM ten Berg
Reference
Circulation. 2020 Aug 31. Epub ahead of print.
Published
August 2020
Link
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Our Comment
Why this study? – the rationale/objective
Even though the most contemporary trials report 15 % occlusion rates of saphenous vein grafts (SVG) within the first year of coronary artery bypass graft (CABG) operation, they are primarily used as the alternative graft option. To date, a few trials have investigated whether dual antiplatelet therapy (DAPT) would increase the patency rates of SVGs, yet provided contradictory results.
The POPular CABG study evaluated the efficacy and safety of ticagrelor on SVG patency when added to low-dose aspirin in post-CABG patients.
How was it executed? – the methodology
The POPular CABG is a randomized, double-blind, placebo-controlled and multicenter trial, which included a total of 499 post-CABG patients with ≥1 SVGs who were on low-dose aspirin preoperatively and continued aspirin during the operation. After successful CABG with SVG implantation, patients were randomized to receive ticagrelor (n=247) or placebo (n=249) on top of low-dose aspirin.
The primary outcome of the study was the total occlusion of SVG at one year on computed or invasive coronary angiography. The secondary outcome was SVG failure, defined as the composite of SVG occlusion, revascularization of SVG, myocardial infarction in SVG territory, or sudden death. Bleeding Academic Research Consortium (BARC) minor and major bleedings were recorded as safety outcomes.
What is the main result?
At one year of randomization, 220 patients (484 SVGs) in the ticagrelor group and 223 patients (470 SVGs) in the placebo group were suitable for assessing primary outcome. In the ticagrelor group, 31 patients had an occluded SVG (14.1%) when compared to 27 patients (12.1%) in the placebo group (OR 1.19, [95% CI: 0.69 - 2.08], P =0.54). The results did not also reveal significant difference when analyzed on a per SVG basis. Moreover, secondary outcomes and safety endpoints were found to be similar in both groups.
Critical reading and the relevance for clinical practice:
The results of the current study show that adding ticagrelor to standard low-dose aspirin therapy does not improve SVG patency and clinical events secondary to SVG failure in patients undergoing CABG at one year. These findings conflict with the results of DACAB study which demonstrated the benefit of aspirin + ticagrelor on SVG patency compared to aspirin alone in a similar patient population, and two plausible reasons may be postulated for this contradiction.
Firstly, the SVG occlusion rate at one year of DACAB trial was higher than POPular CABG (23.5 vs 9.1%, respectively) which can be explained by the fact that while 75.8 % of patients underwent "off-pump" surgery in DACAB, nearly all patients were performed "on-pump" in the current trial. Secondly, DACAB study included more acute coronary syndrome (ACS) patients than POPular CABG (66.4 % vs 31 %, respectively), and this might have influenced the effects of ticagrelor on SVG patency.
Of note, even though no significant effect of adding ticagrelor to aspirin on SVG patency could be found in the ACS subgroup of POPular CABG, that should not be taken as a recommendation against the current guidelines on ticagrelor use in ACS patients undergoing CABG.
To conclude, in POPular CABG trial adding ticagrelor to standard dose aspirin therapy did not significantly change SVG patency, SVG failure and bleeding rates one year after CABG.
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