The optimal second arterial graft and sex differences in coronary bypass surgery: 10-year national registry results

In a 10-year national registry study of over 14,000 patients, neither the right internal thoracic artery nor the radial artery as a second graft significantly impacted long-term survival in either sex, though the radial artery was associated with higher repeat revascularization in men and more cerebrovascular accidents in women.

The Gist

Imagine your heart is a bustling city with a complex network of roads (arteries) delivering essential supplies (blood) to every neighborhood. When these roads get clogged with traffic jams (blockages), surgeons perform a "bypass" surgery. They build new bridges (grafts) using pipes taken from other parts of your body to reroute the traffic around the blockages.

For decades, the gold standard has been using one specific bridge made from a pipe in the chest (the Left Internal Thoracic Artery). But surgeons have long debated: What is the best second bridge to build?

Should they use a pipe from the other side of the chest (Right Internal Thoracic Artery) or a pipe from the arm (Radial Artery)?

This study, a massive 10-year look at over 14,000 patients in the Netherlands, tried to answer that question while also asking: Does the answer change if the patient is a man or a woman?

Here is the breakdown of their findings, translated into everyday language:

The Big Picture: The "Survival" Race

The researchers wanted to know if picking one type of second bridge over the other would help patients live longer.

• The Result: It didn't matter for long-term survival. Whether a patient got the "chest-to-chest" bridge or the "chest-to-arm" bridge, the number of people alive 10 years later was essentially the same for both men and women.
• The Analogy: Think of it like choosing between two different brands of tires for a car. Both brands get you to the same destination safely over the long haul; neither brand guarantees you'll live longer than the other.

The Twist: Different Roads, Different Potholes

While the long-term survival was the same, the journey had some distinct bumps in the road depending on which bridge you chose and whether you were a man or a woman.

1. The "Arm Pipe" (Radial Artery) Issues

• For Men: The arm pipe seemed to wear out faster. Men who got this second bridge needed more "road repairs" (repeat surgeries or stents) within 5 years compared to men who got the chest pipe.
  • Why? The arm pipe might be more prone to getting clogged up again (like a garden hose that kinks easily) in men.
• For Women: The arm pipe was associated with a slightly higher risk of a "traffic accident" in the brain (a stroke or CVA) right after surgery.
  • Why? This might be because women generally have more complex health histories (like diabetes or high blood pressure) that make the arm pipe more fragile, or because the surgery using this pipe involved more manipulation of the heart's main pump, increasing the risk of a tiny clot traveling to the brain.

2. The "Chest Pipe" (Right Internal Thoracic Artery) Issues

• For Everyone (Men and Women): Using the second pipe from the chest caused more "electrical static" in the heart after surgery.
  • The Analogy: Taking two pipes from the chest is like doing a bigger, more invasive construction project inside the house. This causes more inflammation and irritation, leading to a higher chance of the heart rhythm getting jumpy (arrhythmia) right after the operation.

The "Why" Behind the Differences

The study suggests that men and women are biologically different "cities."

• Men seem to handle the "arm pipe" well initially, but it might clog up faster over time, leading to more repeat repairs.
• Women seem to be more sensitive to the stress of the surgery when using the "arm pipe," leading to a slightly higher risk of immediate complications like strokes.

The Bottom Line

The study concludes that there is no single "perfect" second bridge for everyone.

• If you are a man, the arm pipe might save you money in the long run (fewer repeat surgeries), but the chest pipe might be safer for your heart rhythm right after the operation.
• If you are a woman, the chest pipe might be safer for your brain during the immediate recovery, even though the arm pipe is often used.

The Takeaway: Surgeons shouldn't just pick a bridge based on a rulebook. They need to look at the specific "city" (the patient) they are working on. For women, extra caution is needed with the arm pipe to avoid strokes. For men, the arm pipe might need extra monitoring to prevent it from clogging up later.

This research is a wake-up call to stop treating all hearts the same and start tailoring the surgery to the specific needs of men and women.

Technical Summary

1. Problem Statement

Coronary artery bypass grafting (CABG) using multi-arterial grafting (MAG) is superior to single-arterial grafting regarding long-term survival and major adverse cardiac events. While the Left Internal Thoracic Artery (LITA) is the gold standard, the optimal choice for a second arterial graft remains debated. The two primary candidates are the Right Internal Thoracic Artery (RITA) and the Radial Artery (RA).

Existing evidence, particularly the RAPCO-RITA trial, suggests the RA may offer superior long-term patency. However, women are frequently underrepresented in clinical trials, and they face higher risks of graft failure and mortality post-CABG due to comorbidities (e.g., diabetes, hypertension) that may specifically affect RA durability. It is currently unclear whether the benefits of the RA as a second graft are consistent across sexes or if sex-specific factors (such as RA susceptibility to atherosclerosis in women) necessitate different surgical strategies.

2. Methodology

• Study Design: A retrospective analysis of a prospective national registry.
• Data Source: The Netherlands Heart Registration (NHR), covering all cardiothoracic surgical centers in the Netherlands.
• Study Period: January 2013 to December 2022.
• Population: 14,196 patients undergoing primary isolated CABG with LITA + (RITA or RA).
  • Exclusion Criteria: Prior cardiac surgery or use of more than two arterial grafts.
  • Stratification: Patients were stratified by sex (Male vs. Female) and second graft type (RA vs. RITA).
• Statistical Analysis:
  • Confounding Adjustment: Inverse Probability Treatment Weighting (IPTW) based on propensity scores was used to balance baseline characteristics (age, comorbidities, kidney function, LVEF, procedural urgency, etc.).
  • Primary Outcome: Long-term all-cause mortality.
  • Secondary Outcomes: Repeat revascularization, short-term postoperative complications (CVA, arrhythmias, death, repeat surgery).
  • Tools: Kaplan-Meier survival analysis, Cox proportional hazard modeling, and competing risk analysis for repeat revascularization.

3. Key Contributions

• Sex-Specific Analysis: Unlike previous studies that often pool data, this study explicitly analyzes the interaction between graft type and sex in a large, real-world cohort.
• Real-World Evidence: Provides 10-year data from a national registry, offering a broader perspective than single-center randomized controlled trials (RCTs).
• Clarification of Conflicting Data: Addresses the discrepancy between the RAPCO-RITA trial (favoring RA) and observational data regarding sex-specific outcomes.

4. Results

Baseline Characteristics:

• Unadjusted: RA patients were generally younger with fewer comorbidities than RITA patients.
• Adjusted (IPTW): Baseline characteristics were well-balanced between groups for both sexes (Standardized Mean Difference < 0.10).
• Operative Data: Off-pump surgery was more common in the RITA cohort. The RA cohort required more concomitant venous grafts.

Primary Outcome (Long-Term Mortality):

• No Significant Difference: After adjustment, the choice of second graft (RA vs. RITA) did not significantly impact long-term survival in either men ($p=0.32$) or women ($p=0.72$).

Secondary Outcomes:

• Repeat Revascularization:
  • Men: The RA cohort had a significantly higher risk of repeat revascularization at 2 and 5 years compared to RITA.
  • Women: No significant difference in repeat revascularization rates between RA and RITA.
• Postoperative Arrhythmias (POAF):
  • RITA use was associated with a higher incidence of arrhythmias in both men (20.5% vs. 16.4%) and women (20.1% vs. 15.2%) compared to RA.
• Cerebrovascular Accidents (CVA):
  • Women: The RA cohort had a significantly higher rate of CVA (0.9% vs. 0.2%, $p=0.028$).
  • Men: No significant difference in CVA rates.

5. Significance and Conclusion

• Survival Parity: The study confirms that for long-term survival, neither the RA nor the RITA is superior as a second graft in either sex when used in MAG.
• Sex-Specific Risks:
  • Men: May face higher long-term failure rates (repeat revascularization) with the RA, potentially due to RA susceptibility to intimal hyperplasia and atherosclerosis in the male population.
  • Women: May face higher perioperative risks (CVA) with the RA, potentially linked to the higher use of on-pump surgery and concomitant vein grafts in this cohort, alongside baseline comorbidities.
• Clinical Implication: The findings challenge the notion that the RA is universally the superior second graft. The authors suggest that sex-specific considerations should be integrated into preoperative planning. While the RITA carries a higher risk of arrhythmias (likely due to increased surgical trauma/inflammation from bilateral internal thoracic artery harvesting), the RA carries sex-specific risks regarding graft patency (men) and cerebrovascular events (women).
• Future Directions: The authors call for large-scale prospective trials to validate these sex-specific findings and optimize grafting strategies, noting that women remain underrepresented in current cardiovascular research.

Limitations: Retrospective nature (selection bias), potential unmeasured confounding, lack of data on incomplete revascularization, and missing data on specific grafts involved in repeat interventions.