SYNTAX Substudy: CABG’s Edge Over PCI Extends to Long-Term QoL

Four years ago, final clinical results from the multicenter SYNTAX trial showed that patients with three-vessel or left main coronary artery disease (CAD) who undergo bypass surgery have better major adverse cardiovascular outcomes at five years than their matched counterparts who undergo percutaneous coronary intervention (PCI) with a first-generation drug-eluting stent (DES). Now a health status substudy of SYNTAX finds that the bypass recipients are also more likely to enjoy a higher quality of life over the long term.

The new results, published in the April 25, 2017, issue of the Journal of the American College of Cardiology, provide further support to coronary artery bypass graft surgery (CABG) as the preferred revascularization option for patients with anatomically complex three-vessel or left main CAD.

“Both CABG and PCI with a DES were associated with substantial and sustained quality-of-life benefits over five years of follow-up,” explains the study’s first author, Cleveland Clinic cardiologist Mouin S. Abdallah, MD. “But CABG provided greater angina relief at five years, primarily due to an advantage among patients with anatomically complex disease as reflected by higher SYNTAX scores.”

Substudy design essentials

The new substudy was designed as a prospective health inventory of patients randomized in the SYNTAX (Synergy Between PCI with Taxus and Cardiac Surgery) trial to either CABG or PCI with the first-generation paclitaxel-eluting stent TAXUS.

Patients’ health status was evaluated at baseline and at multiple time points after revascularization (1, 6, 12, 36 and 60 months) using the CAD-specific Seattle Angina Questionnaire (SAQ) and the more general 36-Item Short Form Health Survey (SF-36).

Of the 1,800 initial SYNTAX enrollees, 1,731 had baseline health status data and were included in the substudy analysis; complete health status data were available through the full five years of follow-up for 1,222 patients.

Key findings mirror clinical results

At five years of follow-up, CABG was statistically significantly superior to PCI on several SAQ domains, including angina frequency and physical function, as well as on the “role physical” and “role emotional” subscales of the SF-36.

Subgroup analysis showed a significant interaction (P = .048) between angiographic complexity (i.e., SYNTAX score ≥ 23) and angina relief. “This reinforces the recommendation that CABG should be strongly preferred for patients with high SYNTAX scores, which aligns with findings from the study’s primary clinical analysis,” notes Dr. Abdallah.

Among other notable findings:

• Angina relief was associated with both CABG and PCI as early as one month following revascularization, and the benefit largely endured throughout the five years.
• Health status recovery was faster following PCI compared with CABG.
• CABG yielded significantly greater benefits in cardiac-specific and general health status measures at one and five years, but the absolute difference from the benefits with PCI was relatively small and of unclear clinical relevance.
• The superiority of CABG for angina relief was consistent across most prespecified characteristics, including age, presence or absence of diabetes, and whether patients had three-vessel or left main disease.

“The long-term health status differences observed in this trial were comparable to those seen in FREEDOM, another contemporary trial comparing CABG and PCI with a drug-eluting stent to assess long-term outcomes, albeit in patients with diabetes and multivessel CAD,” notes Dr. Abdallah, who also served as first author of the FREEDOM study report published in JAMA in 2013.

PCI still an option in less complex disease

He adds that while this cumulative evidence clearly makes CABG the revascularization treatment of choice for high-risk patients, for patients with anatomically less complex disease, PCI with a DES remains a reasonable alternative, particularly given the substantial and sustained quality-of-life gains seen with both revascularization strategies. “For patients with a SYNTAX score below 23, a comprehensive heart team approach should be used to explore and weigh both options according to the patient’s preferences and priorities,” he says.

Dr. Abdallah and his SYNTAX co-investigators conclude their study report with a call for future trials to explore whether new-generation DESs might yield benefits more comparable to those of CABG for this patient population.