CABG vs PCI in Left Main Disease: The Debate Continues

WASHINGTON, DC—The debate over which patients with left main coronary artery disease should be treated with PCI versus CABG remains unsettled, with experts at CRT 2019 comparing the late and early advantages of both procedures.

Reviewing the 4-year data from EXCEL that were first presented at TCT 2018, Gregg W. Stone, MD (Columbia University Irving Medical Center, New York, NY), argued that while PCI is less invasive, has fewer periprocedural complications, and is associated with lower 30-day MACE, more rapid recovery, better quality of life, and earlier angina relief, bypass surgery has more late advantages. These include lower 30-day and 4-year rates of major adverse cardiac events and fewer repeat revascularization procedures.

“Overall, PCI and CABG had comparable 4-year prognosis and 3-year quality of life, so obviously there needs to be a heart team discussion [that takes] the patient preferences into account when deciding between PCI and CABG for low- and intermediate-risk Syntax score patients with left main disease,” Stone said.

However, Robert Guyton, MD (Emory Healthcare, Atlanta, GA), a cardiovascular surgeon, pointed out that mortality is a persuasive argument in favor of CABG: in EXCEL, CABG was associated with significantly less death than PCI at 4 years (7.4% vs 10.3%; P = 0.04).

Stone countered, however, that because this 2018 meta-analysis of 4,478 patients with left main disease enrolled in 11 trials of CABG versus PCI, including EXCEL, showed “almost identical” 5-year all-cause mortality rates (10.5% vs 10.7%; P = 0.52), the difference observed in EXCEL—which was driven by a difference in definite noncardiovascular mortality—was “probably a red herring.”

Focus on LAD Patency, Threatening Lesions

The two key concepts to be determined when deciding how to treat left main stenoses are the long-term patency of the left anterior descending (LAD) artery as well the importance of future threatening lesions, Guyton said. “PCI and coronary bypass are different complementary procedures—coronary bypass bypasses the current flow-limiting stenosis and future threatening stenoses. PCI deals only with the fibroatheromas under the stent.”

In terms of “how much heart [you] need to survive,” it’s thought that the LAD supplies about 50%, the right coronary artery 20%, and the circumflex 30%, Guyton reminded his audience.

“Because of collateral flow, you lose your right, you lose almost no muscle in the LV. Circumflex, not too much muscle. LAD, however, you lose 25-30%. You lose the right and the circumflex because of collateral flow from the LAD, you're still losing only maybe 30% in a typical patient; but the LAD and the right occluded, about 50%, and the LAD and the circumflex occluded, you're toast,” he explained. “So . . . if the LAD is patent, the patient likely will survive. Hence, the dominant survival benefit of the left internal mammary artery to the LAD with 90-plus percent 20-year patency.”

Secondly, he stressed that while “coronary bypass bypasses present and future threatening lesions,” PCI typically only treats the lesion of interest. Indeed, Guyton cited autopsy series that show that PCI deals with discrete vessel segments, but fails to protect the areas where most lesions occur. “The left internal mammary to the LAD protects against 58% of threatening lesions,” he said. “A 20-mm stent covers about 18% of threatening lesions, hence the continuing increased latent MI rate for stents versus cardiac bypass.”

New York State data have previously shown the proportion of patients with multivessel and proximal LAD disease treated with CABG rather than PCI decreased from 2005 to 2015. As Guyton observed, though, this shift is counterintuitive, given that the relative excess mortality carried by PCI remains about 30% in trials and registries. “Is this evidence-based medicine? The superiority of cardiac bypass over PCI with regard to survival and relief of angina for more than the simplest multivessel disease has been established, but patients undergoing PCI generally erroneously believe that PCI prolongs life and prevents future infarction in a manner similar to cardiac bypass,” Guyton stressed.

“What patients want is the lowest immediate risk, avoidance of pain, [and] rapid return to normal, all favoring PCI,” he continued. “But to maximize benefit, you need cardiac bypass.”

For Guyton, the choice if he himself needed revascularization was clear. “If you'll give me an internal mammary graft to the LAD, you can do whatever you want to my other two vessels. This leads us to hybrid revascularization with a robotic mammary to the LAD, a stent to the other vessel, and I still think this is the future of cardiac revascularization,” he concluded.

Stone, for his part, urged his audience to stay tuned for more data. Five-year outcomes from EXCEL will be out at TCT 2019, he said.