Should We Use Bilateral Internal Thoracic Artery for Patients on Hemodialysis?

Grafting of the internal thoracic artery (ITA) to the left anterior descending coronary artery gives the best long-term survival outcome compared with other types of grafts. Lytle et al recommended bilateral ITA (BITA) a decade ago,¹ and in 2001 Taggart et al recommended BITA after a systematic review.² However, to realize the benefit of BITA demands long-term follow-up because of the powerful beneficial potential of left ITA itself.

Article p 2004

The Arterial Revascularization Trial (ART) is an only international multicenter randomized study enrolling more than 31,000 patients and it concluded there was no difference in the primary endpoint of death at 10 years (20.3% in the BITA group and 21.2% in the SITA group: P=0.62), indicating there is no rationale to use BITA in coronary artery bypass grafting.³

There are, however, some confusing methodological problems with that study. Taggart et al honestly did an as-treated analysis to compare outcomes in patients who underwent SITA with other vein grafts and outcomes in patients who received ≥2 arterial grafts, showing 8% difference in absolute survival in favor of multiple arterial grafts and likewise a highly significant reduction in the composite of death, myocardial infarction and stroke, with divergence between the groups although it was not randomized study.³

After the ART trial, there have been many studies recommending the use of BITA. Zhu et al reported BITA improved long-term survival compared with SITA, showing 5- and 10-year survival rates of 61.1% vs. 58.3% and 37.7% vs. 34.9 respectively.⁴ Saraiva et al reported their meta-analysis of 29 propensity score studies and 8 randomized control studies comparing BITA and SITA and concluded that although BITA increases the risk of sternal wound complication, multiple arterial grafting improves both early and long-term survival as well as major adverse cardiac and cerebrovascular events (MACCE).⁵

Limitation for the Use of BITA

Although there are many recommendations for BITA, its use in Europe is ≈20% of all cases and as low as 5–10% of cases in the USA.⁶ In Japan, ≈50% of younger patients (≤60 years old) underwent BITA grafting, as did 35% of even older patients ( >60 years old).⁷

The reasons for the limited use of BITA in Western countries are complex operation, long operation time, lack of familiarity, and concerns about sternal wound complications.⁸

In this issue of the Journal, Hachiro et al⁹ studied the benefit of BITA for hemodialysis (HD) patients, who are one of the highest-risk group of patients. They conclude that BITA did not improve mid-term outcomes, but was not associated with worse postoperative outcomes. However, they emphasize that using BITA for HD patents might reduce stroke incidence. Dr. Hachiro’s group has been reporting the benefit of BITA. It has a better survival rate than SITA in diabetic patients,¹⁰ elderly patients,¹¹ and high-risk (>EuroScore 5) patients.¹² In 2010 they reported BITA had better long-term survival than SITA in 46 dialysis patients, and 10 years later in 2020, they again compared BITA and SITA for 107 diabetic nephropathy (HD) patients and changed their conclusion, saying there was no difference between the 2 groups.¹³ And here again they came to the same conclusion for 145 HD patients.⁹

There is a little bit of confusion that they concluded BITA would carry benefit in one sub-group, but not in another sub-group of patients. It might depend on study volume and follow-up duration. It adds to the chaos of deciding to use or not to use BITA. To prove the benefit of BITA looks very difficult, as in the ART study.

Prognosis of Hemodialysis Patients

In Japan, 344,640 patients are receiving chronic HD, which is the third biggest number following USA and China. That equates to 2,731 patients out of 1 million population being treated by HD, and the number of HD patients per million population is the biggest in the world. However, the prognosis after the initiation of HD in Japan is much better than other countries. Authors cited the United States Renal Data System, stating that the 5-year survival rate is only 39.8%. However, according to the annual report of The Japanese Society for Dialysis Therapy¹⁴ (Figure), the 1-, 5- and 10-year survival rates are 89.9%, 60.8% and 35.9% respectively. As mentioned above, it requires long-term follow up to show the benefit of BITA after CABG, maybe >10 years. Even in Japan, the 5-year survival rate is 60% after the initiation of HD. Hachiro et al reported the 5-year survival rate was 51.7% and 60.6% in the SITA and BITA groups respectively, which seems very similar to all HD patients. And it is again understandable that there would be no differences between the SITA and BITA groups’ 5-year survival rates.

Figure.

Changes in the 1-, 5-, 10-, 15-, 20-, 25- and 30-year survival rates after the initiation of hemodialysis (Reproduced from Masakane I et al¹⁴ with permission).

Should We Use BITA for Patients on HD?

The natural survival rate of patients on HD is not so long, and to see the benefit of BITA needs long-term follow up. There is still concern about BITA usage, including sternal wound infection, long operation time and no benefit for long-term survival improvement. In this study, the operation time was significantly longer in the BITA group than in the SITA group (251 vs. 220 min, P<0.001). So why should we use BITA for HD patients? It becomes difficult to believe in using BITA for HD patients. In their study, the authors confess there was no survival rate difference between the BITA and SITA groups.⁹

The only benefit is reducing postoperative stroke. Should we use the strategy of BITA to reduce postoperative stroke? Of course, the aorta no-touch technique is a strategy for stroke reduction. However, there are other strategies. One is to use anastomosis devices for the proximal anastomosis. The authors used partial clamping for 65.6% of the SITA group and used anastomotic devices for 18.6%;⁹ however, if they had used the devices more frequently, the stroke rate might have been lower. Saito et al reported no differences between device anastomosis and no-touch technique from data of the Japanese Adult Cardiovascular Surgery Database.¹⁵ In any case, to reduce stroke, routine BITA usage for the patients on HD is debatable.

Summary

In Japan, many surgeons are not reluctant to use BITA compared with surgeons in other countries. I also believe in BITA usage considering the long-term patency rate, production of nitroxide, similar caliber to coronary artery and reduction of aortic manipulation. However, I would strongly suggest we consider patient selection, with regard to age, comorbidity, and life expectancy.

References

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