Second Arterial Versus Venous Conduits for Multivessel Coronary Artery Bypass Surgery in California

Abstract

Background: Whether a second arterial conduit improves outcomes after multivessel coronary artery bypass grafting remains unclear. Consequently, arterial conduits other than the left internal thoracic artery are seldom used in the United States.

Methods: Using a state-maintained clinical registry including all 126 nonfederal hospitals in California, we compared all-cause mortality and rates of stroke, myocardial infarction, repeat revascularization, and sternal wound infection between propensity score-matched cohorts who underwent primary, isolated multivessel coronary artery bypass grafting with the left internal thoracic artery, and who received a second arterial conduit (right internal thoracic artery or radial artery, n=5866) or a venous conduit (n=53 566) between 2006 and 2011. Propensity score matching using 34 preoperative characteristics yielded 5813 matched sets. A subgroup analysis compared outcomes between propensity score-matched recipients of a right internal thoracic artery (n=1576) or a radial artery (n=4290).

Results: Second arterial conduit use decreased from 10.7% in 2006 to 9.1% in 2011 (P<0.0001). However, receipt of a second arterial conduit was associated with significantly lower mortality (13.1% versus 10.6% at 7 years; hazard ratio, 0.79; 95% confidence interval [CI], 0.72-0.87), and lower risks of myocardial infarction (hazard ratio, 0.78; 95% CI, 0.70-0.87) and repeat revascularization (hazard ratio, 0.82; 95% CI, 0.76-0.88). In comparison with radial artery grafts, right internal thoracic artery grafts were associated with similar mortality rates (right internal thoracic artery 10.3% versus radial artery 10.7% at 7 years; hazard ratio, 1.10; 95% CI, 0.89-1.37) and individual risks of cardiovascular events, but the risk of sternal wound infection was increased (risk difference, 1.07%; 95% CI, 0.15-2.07).

Conclusions: Second arterial conduit use in California is low and declining, but arterial grafts were associated with significantly lower mortality and fewer cardiovascular events. A right internal thoracic artery graft offered no benefit over that of a radial artery, but did increase risk of sternal wound infection. These findings suggest surgeons should consider lowering their threshold for using arterial grafts, and the radial artery may be the preferred second conduit.

Keywords: coronary artery bypass; internal thoracic artery; propensity score; radial artery.

Figure 1.

Patient Selection Flow Diagram. CABG, coronary artery bypass grafting; CAD, coronary artery disease; ITA, internal thoracic artery

Figure 2.

Mortality and Major Adverse Cardiovascular and Cerebrovascular Events after Coronary Artery Bypass Surgery. All-cause mortality (Panels A and C) and the incidence of major adverse cardiovascular and cerebrovascular events (Panels B and D) are plotted against time after surgery and stratified according to conduit type. Numbers of patients at risk are included below each figure. Note that some numbers are not necessarily integers due to matched pairs with variable controls. ITA, internal thoracic artery; MACCE, major adverse cardiovascular and cerebrovascular events

Figure 3.

Age-Dependent Hazard of Death for Second Arterial versus Venous Conduits. The hazard ratio of death for recipients of second arterial versus venous conduits is plotted against age as a continuous variable. The dashed lines represent 95% confidence intervals obtained from bootstrap resampling. The horizontal black line at 1 denotes no difference between conduit types. The vertical grey line at 78 years denotes the age when the upper 95% confidence interval crosses the null.