Myth Busters: Does Coronary Artery Bypass Grafting Impact Progression of Native Coronary Artery Disease?

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1 Myth Busters: Does Coronary Artery Bypass Grafting Impact Progression of Native Coronary Artery Disease? Bobby Yanagawa MD PhD FRCSC Division of Cardiac Surgery St Michael s Hospital

2 Shifting Our Attention from the Bypass Graft to the Upstream Coronary Artery

3 We defined malignant graft failure after CABG to be bypass graft occlusion and de novo complete occlusion of the target native coronary artery proximal to the graft anastomosis site. if the proximal lesion in the native coronary artery progresses from 99% stenosis to occlusion, then the difficulty and risk associated with PCI increase... CTO of surgically bypassed coronary arteries 1 year after coronary artery bypass grafting is extremely common.

4 THE MYTH Coronary artery bypass grafting causes progression of native vessel disease by competitive flow resulting in stasis in the upstream vessel

5 Focused Questions Is bypass ASSOCIATED WITH native vessel disease progression? Does bypass CAUSE native vessel disease progression? Is native vessel disease progression associated with adverse clinical outcome? Is there any treatment to reduce native vessel disease progression?

6 IS CABG ASSOCIATED WITH NATIVE VESSEL DISEASE PROGRESSION?

7 Greater Progression in Grafted Segments 42 patients with stable angina 10 years post-randomization to medical management or CABG (SVG) in the VA Trial Hwang, JACC. 1990;16:1066

8 Disease Begets Disease Hwang, JACC. 1990;16:1066

9 Less progression with arterial grafts

10 Greater Progression with Lesion Severity: Insights from the RAPCO Trial Hayward, J Thorac Cardiovasc Surg. 2013;145:140.

11 IS NATIVE VESSEL DISEASE PROGRESSION CAUSED BY CABG?

12 Retrospective Analysis of CABG Identification of moderate and severe lesions Bypass Progression VS No Bypass Progression THE SURGEON s DECISION MAKING CONCLUSION: Bypass is associated with greater progression

13 Potential Source of Bias: The Surgeon There is an important systematic bias that make it very difficult to confidently answer this question in retrospective series The surgeons choice of which vessels to bypass is an uncontrolled but consistent confounder The surgeon will bypass threatening lesions: Irregular, calcified or long lesions Moderate lesions closer to 70% than 40% Severe lesions closer to 100% than 70% all of which are more likely to progress

14 IS NATIVE VESSEL DISEASE PROGRESSION ASSOCIATED WITH ADVERSE CLINICAL OUTCOME?

15 Native Progression is Not In-Stent Restenosis LAD_large.jpg

16 Review of 95 patients with UA or NSTEMI >6mo post-cabg The culprit vessel was Vein graft failure 66% Progression in an ungrafted vessel 22% Progression in a grafted vessel 12% (proximal to anastamosis in 33% and distal in 67%) Vein graft failure vs native progression 53% vs 47% <5 years post-cabg 76% vs 14% 5-10 years post-cabg 92% vs 8% >10 years post-cabg

17 IS THERE ANY TREATMENT TO REDUCE NATIVE VESSEL DISEASE PROGRESSION?

18 DAPT Is Associated with Reduction in Native Progression Post-CABG Post-Hoc Analysis of the CASCADE Trial Comparison of angiograms pre- and 1 year post-cabg in 92 patients Grading: 0 0% 24% 1 25% 37% 2 38% 62% 3 63% 82% 4 83% 98% 5 99% 100% Une, Circulation. 2014; 130:S12

19 DAPT Is Associated with Reduction in Native Progression Post-CABG DAPT is associated with. Reduction in overall mean grade 1.1±1.0 vs 1.6±1.1; p=0.01 Reduction in mean grade in diabetics 1.0±0.8 vs 1.8±1.0; p=0.02 No difference in non-diabetics 1.2±1.1 vs 1.4±1.1; p=0.3

20 Focused Questions IS CABG ASSOCIATED WITH NATIVE VESSEL DISEASE PROGRESSION? YES IS NATIVE VESSEL DISEASE PROGRESSION CAUSED BY CABG? MAYBE IS NATIVE VESSEL DISEASE PROGRESSION ASSOCIATED WITH ADVERSE CLINICAL OUTCOME? IS THERE ANY TREATMENT TO REDUCE NATIVE VESSEL DISEASE PROGRESSION? YES (but few cases) MAYBE (DAPT)

21 THANK YOU John D Puskas MD Icahn School of Medicine at Mount Sinai and Mount Sinai Beth Israel Robert F Tranbaugh MD Mount Sinai Beth Israel