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Outcomes associated with bilateral internal thoracic artery grafting: the importance of age
Teresa M Kieser1, Adriane M Lewin, Michelle M Graham
1Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada. t.kieserprieur@ucalgary.ca
Insights
Bilateral internal thoracic artery (BITA) grafting offers survival benefits in coronary artery bypass grafting (CABG) patients under 70. Further research is needed to confirm long-term advantages for older patients.
Area of Science:
- Cardiovascular Surgery
- Thoracic Surgery
- Medical Research
Background:
- Bilateral internal thoracic artery (BITA) grafting in coronary artery bypass grafting (CABG) is linked to positive outcomes.
- A debate exists regarding the age threshold beyond which BITA grafting ceases to be beneficial.
Purpose of the Study:
- To investigate if an age cutoff exists for the efficacy of BITA grafting in CABG patients.
- To compare survival rates between BITA, single internal thoracic artery (SITA), and vein-only grafts.
Main Methods:
- Analysis of 5,601 isolated CABG patients from a cardiac surgery registry (1995-2008).
- Utilized Cox regression to compare survival, adjusting for clinical and demographic factors.
- Employed spline analysis to assess the impact of age on BITA grafting outcomes.
Main Results:
- BITA grafting showed the lowest 1-year mortality (2.4%) compared to SITA (4.3%) and vein-only (8.2%) grafts.
- Crude survival benefit for BITA vs. SITA was 54%, but this became non-significant after adjustment (HR 0.87).
- Spline analysis indicated a potential survival advantage for BITA grafting in patients younger than 69.9 years.
Conclusions:
- BITA grafting is a viable strategy for suitable patients up to age 70.
- Long-term follow-up is necessary to fully ascertain the benefits of BITA grafting.
- The advantage of BITA grafting in patients over 70 remains unclear.
Background:
Although bilateral internal thoracic artery (BITA) grafting in coronary artery bypass grafting (CABG) is associated with low morbidity and good long-term results, controversy exists about the age after which BITA grafting is no longer beneficial. We sought to determine if such an age cutoff point exists.
Methods:
The study cohort consisted of 5,601 consecutive patients from a cardiac surgery registry who underwent isolated CABG (1,038 [19%] BITA grafts, 4,029 [72%] single internal thoracic artery [SITA] grafts, 534 [10%] vein-only grafts) between 1995 and 2008. A Cox model was used to compare survival by use of bilateral, single, or no internal thoracic artery (ITA) grafts, adjusting for baseline clinical and demographic characteristics.
Results:
Mean follow-up was 7.1 years. Patients undergoing BITA grafting had the lowest 1-year mortality (2.4% versus 4.3% SITA grafting and 8.2% vein-only grafting; p < 0.0001). Relative to SITA grafting, a crude survival benefit of 54% existed for BITA grafting (hazard ratio [HR] 0.46; 95% confidence interval [CI], 0.37 to 0.57; p < 0.0001) with worse survival for vein-only grafts (HR, 1.16; 95% CI, 0.99 to 1.37; p = 0.07). After adjustment, the benefit of BITA grafting was no longer statistically significant (HR, 0.87; 95% CI, 0.69 to 1.08; p = 0.2). However age may be an effect modifier: a spline analysis plotting HR (BITA grafting versus SITA grafting) against age suggested a potential survival advantage associated with BITA grafting in patients younger than 69.9 years.
Conclusions:
Bilateral internal thoracic artery grafting is a reasonable revascularization strategy in suitable patients up to age 70 years. As benefits of arterial grafting become more obvious over time, a longer period of follow-up will be needed to confirm the advantage of a BITA grafting strategy. In the meantime the BITA grafting advantage for patients older than 70 years is not clear.
