Different myocardial revascularization models exist for multivessel coronary disease, with ongoing debate as to whether a multiarterial graft (MAG) strategy using the internal mammary artery (IMA) and/or radial artery (RA) provides a survival benefit over a single-arterial graft (SAG) combined with a saphenous vein. Previous single-center observational studies have associated MAG with improved survival, but recent clinical trials have not demonstrated statistically significant differences. This study aims to analyze long-term survival in a large population from the Society of Thoracic Surgeons (STS) database to help clarify this controversy.

Sabik et al. designed this multicenter, observational, retrospective study, including all U.S. patients who underwent elective, isolated myocardial revascularization with at least two grafts, one being arterial, between January 2008 and March 2019. Data were sourced from the STS Adult Cardiac Surgery Database and combined with data from the Centers for Disease Control and the National Death Index. Survival outcomes were estimated using Kaplan-Meier methodology, with the hazard ratio (HR) assessed at a 95% confidence interval (95% CI). To adjust results for baseline patient differences between MAG and SAG groups, inverse probability weighting (based on propensity scores), multivariable analysis, time-to-event analysis, and multiple sensitivity analyses were employed. Subgroup analyses (e.g., demographics, patient risk, surgical center volume) further identified potential variability in the effect of multiarterial grafting.

A total of 1021632 patients from 1108 cardiac surgery centers in the U.S. were included. Among them, 100419 patients (9.83%) received multiarterial grafts (47% double IMA, 45.5% IMA and RA), while 920943 patients (90.17%) received a single arterial graft with saphenous vein. Patients in the MAG group were generally younger males with lower incidences of heart failure, hypertension, chronic obstructive pulmonary disease, cerebrovascular disease, or peripheral artery disease, and with better ejection fraction and estimated glomerular filtration rate. However, coronary disease severity, number of grafts, and incomplete revascularization rates were similar in both groups. The median follow-up was 5.3 years (range 0–12 years). Long-term survival was higher in the MAG group at centers performing >10 procedures annually, with an unadjusted HR of 0.59 (95% CI 0.58–0.61) and an adjusted HR of 0.86 (95% CI 0.85–0.88; p = 0.0001), with comparable impact across all subgroups and time-to-event intervals. The observed difference was most significant among younger male patients and less marked in those with comorbidities or without cardiopulmonary bypass. MAG was equivalent to SAG in patients aged >80 years, those with NYHA class IV, severe pulmonary disease, or estimated glomerular filtration rate <45 mL/min, and inferior in patients with morbid obesity (BMI >40 kg/m²).

COMMENTARY:

This study provides an updated, real-world analysis of long-term survival in over a million cases, representing more than 97% of all CABG procedures in the U.S. While the observed benefits of a multiarterial grafting (MAG) strategy are promising, some key points require commentary.

First, patient characteristics across groups were unevenly distributed. The MAG group comprised predominantly younger males with fewer comorbidities, representing a “better patient” cohort. This factor may influence results, as the benefits of MAG were also more pronounced in younger, healthier males. Despite propensity score adjustments, key preoperative and intraoperative conditions (frailty, graft quality, and revascularizable targets) were not evaluated. Multiarterial grafting is sometimes a rescue choice in CABG when a fully arterial revascularization plan is unfeasible. In such cases, saphenous vein grafting becomes an alternative option if arterial graft length or quality, underdeveloped internal mammary arteries, hemodynamic instability, or bleeding risk necessitate adjustments during surgery.

Additionally, the study registry shows that over half (53.6%) of U.S. centers perform multiarterial revascularization in <5% of cases annually, likely to reduce the potential risk of wound complications. Furthermore, choice of arterial graft varies, with approximately 47% using double IMAs and 45.5% IMA with RA, and only a residual 7.5% using both double IMA and RA. Although similar long-term outcomes have been reported with different arterial grafts, no specific subanalyses were done based on graft type or use of cardiopulmonary bypass.

The threshold for benefit was set at 10 cases annually. A threshold this low raises questions about whether greater experience might yield different outcomes in specific patient profiles, especially those with comorbidities like obesity, small-caliber mammary or coronary arteries, and bleeding risk. Analysis by higher-volume centers with expertise in multiarterial grafting and off-pump revascularization could further elucidate potential benefits. The ART trial demonstrated MAG benefit when stratified by surgeon experience.

Despite retrospective limitations, the survival outcomes align with the recent Spanish meta-analysis by Urso et al. (previously discussed) and PRIORITY, a multicenter cohort study. Nonetheless, the ROMA trial (Randomized comparison of the clinical Outcome of single vs Multiple Arterial grafts, also reviewed here) is anticipated to provide further evidence in this debate.

In conclusion, pending the results of the ROMA trial, this extensive observational study supports MAG as associated with improved long-term survival for most patients undergoing CABG.

REFERENCE:

Sabik JF 3rd, Mehaffey JH, Badhwar V, Ruel M, Myers PO, Sandner S, et al. Multiarterial vs Single-Arterial Coronary Surgery: 10-Year Follow-up of 1 Million Patients. Ann Thorac Surg. 2024 Apr;117(4):780-788. doi: 10.1016/j.athoracsur.2024.01.008.